abstract list - Central Power Research Institute



abstract list - Central Power Research Institute
Vol. l. No. l, September 2004
THE JOURNAL OF CPRI - Vol. l, No. l, September 2004
A Novel Control Strategy for TCSC to Damp Subsynchronous Oscillations
Sujatha Subhash, B.N. Sarkar and K.R. Padiyar
Thyristor Controlled Series Compensators (TCSC) is the first FACTS controller under the new
generation to have reached mature stage of development. The importance of adding series capacitor
to ac transmission lines for increasing line load-ability is known for a long time. But the potential
risk of SSR oscillations had made it undesirable to widely use them in the system. Adding a
thyristor controlled series compensator Laresen et al (1) is however a fairly recent phenomenon
and provides greater flexibility in power transmission, There are several advantages in using
TCSC and reducing the torsional oscillations caused by SSR is one among them. A novel discrete
control strategy to mitigate SSR oscillations is proposed for TCSC having discrete type of control
over compensation level, since it behaves like a conventional series compensation under normal
conditions. The control strategy is based on the Phase unbalance concept and is simple and easy
to implement in the hardware. The concept of Phase unbalance originally proposed by A.Edris (2)
is described followed by theoretical analysis to support the design for practical implementation.
An expression for the damping torque coefficient is given, which is useful to assess the damping
effectiveness quantitatively, over a wide variety of system operating conditions and for arriving
at an optimal design. Extension of this concept to TCSC with discrete control is subsequently
Analysis of Northern Region Electricity Board (NREB) Grid Disturbance
P.V. Bala Subramanyam, B.N. Sarkar and V.J. Talwar Santhosh Kumar
The Northern Regional Electricity Board (NREB) consists of generating and transmission power
utilities of the states UP, Rajasthan, J&K, Punjab, Himachal Pradesh, Haryana, and the central
utilities viz Powergrid, NTPC, NPC, BBMB, DVB etc. NREB is the largest regional electricity
board. The NREB grid experienced several major grid disturbances in the recent past resulting
in cascade tripping of 400 kV lines and generating units. This resulted in separation of grid into
several isolated parts with disruption of power supply. On certain occasions several EHV lines
tripped leading to total blackout. This paper deals with the analysis of the grid disturbance that
occurred on 26th Nov’96. In this paper main emphasis is given to superimpose dynamic variation
of characteristic impedance on relay characteristics. The effectiveness of Power System Stabilizer
(PSS) to avoid/minimize such grid disturbances is attempted.
Insulation Coordination Studies for 400 kV GIS in a Hydroelectric Project in India
B.N. Sarkar, K.S. Meera, Gaurav Garg, Ram Nath, A.K. Tripathy, S.C. Mishra and J. Thomas
Insulation coordination studies comprising of Switching, Lightning and Very Fast Transient
over voltages has been carried out for the 400 kV Gas Insulated Switchgear (GIS) in the Tehri
hydroelectric power plant in India. The studies were carried out to decide the various parameters
of the switchyard equipment including arrester locations. Results of the switching over voltages
have been validated on the Transient Network Analyser (TNA). This paper discusses some of the
results of all these studies.
Vol. l. No. l, September 2004
Leakage Current and Charge in RTV Coated Insulators Under Pollution Conditions
D. Devendranath, Channakeshava and A.D. Rajkumar
Room temperature vulcanizing (RTV) silicone rubber coating has excellent leakage current
suppression characteristics. It is used extensively on porcelain and glass insulators in pollution
prone areas as an anti-pollution measure. A pollution aging chamber has been fabricated and an
on line 4 - channel personal computer (PC) based data acquisition system has been developed to
conduct tests on RTV coated porcelain samples. A study of the dependence of the leakage current
and the charge on the flow rate, conductivity and pressure of the solution forming the fog is
reported. It was observed that a higher charge and a higher average leakage current were obtained
at a higher flow rate and a higher conductivity. The results with coated HV insulators are consistent
with those published in the literature with RTV coated fiber glass reinforced plastic (FRP) rods.
3D Location of Multiple Partial Discharge Sources
H.N. Nagamani and Channakeshava
The ability to locate Acoustic Emission (AE) sources is one of the most important features of the
multi-channel AE detection system. An array of AE sensors is necessary to locate an AE source.
When the AE signals are transient in nature, measurement of time of signal arrival at different AE
sensors is generally employed for source location. AE source is located by measuring the time
delay between two or more AE sensors in the array. Location of AE source requires the knowledge
of the velocity of AE signals in the medium under study, which can be obtained by simulating the
AE sources at known locations within the medium.
In the present study, a multi channel AE system has been employed for detection and location of
partial discharge (PD) or corona sources. PD sources were simulated in transformer insulation
medium by energizing sharp metallic needles positioned at known locations. Velocity of AE PD
signals in transformer oil medium was determined from the value of time delay in receiving AE PD
signals by different sensors. The (x, y, z) co-ordinates of the PD source, i.e. the needle tip, were
estimated with the help of 3D location software. The estimated coordinates of the PD source were
compared with the actual coordinates to verify the accuracy of estimation. This paper discusses the
methodology for estimating the propagation velocity of AE PD signals in transformer oil medium
and 3D location of single and three sources simulated in transformer oil medium. The accuracy of
location results is also discussed.
Performance of Polymeric Insulators under Accelerated Ageing under AC & DC
N. Vasudev, K.N. Ravi, P. Krishna Murthy and Channakeshava
The performance of insulator for AC and DC voltages is of great practical importance as the
insulators can be used with both types of voltages. In view of the many advantages of composite
(polymeric) insulators, extensive experimental and analytical investigations have been carried out
in the present study on the ageing characteristics of these insulators. Inclined plane tracking and
erosion tests, as well as the long term ageing tests, were conducted on samples of polymeric insulator
materials. It has been possible to conclude from the above experiments that positive polarity DC is
more severe for polymeric material compared to negative polarity DC and AC voltages. The surface
degradation of the material was diagonised by hydrophobicity measurement and leakage current
analysis. Analytical techniques such as x-ray Diffraction, Energy Dispersion x-ray have been used
to analyze the material deterioration. Thermo graviometric analysis and Differen tial scanning
calorimeter tests were also used to study the filler material content in the polymer.
Vol. l. No. l, September 2004
Modelling Water Treeing in XLPE Insulation using Electric Field Concepts
S. Ganga, S.N. Moorching and S. Sridhar
A methodology to model water treeing in XLPE insulation by using electric field, elastic deformation
due to pressure build up inside void and probability concepts has been developed. Tree patterns have
been numerically simulated considering point-plane electrode geometry in XLPE insulation. The
strategy of modelling is verified by comparing fractal dimensions of simulated and experimentally
generated tree patterns. The current study revealed, that presence of void filled with moisture is
less harmful to presence of a metallic particle of same dimension and also the growth of bow tie
tree terminates after it develops to a finite size. Depending upon the type of defects such as semi
conducting particle or void filled with air etc, that is present in the insulation, further structure of
the prebreakdown channel resembled electrical.
Corrosion of all Aluminium Alloy Stranded Conductors-A Case Study
Ramakrishna and S. Seetharamu
Aluminium conductor Steel reinforced (ACSR) material has been in use since the beginning of20{]
pl century for transmission and distribution of electrical energy. All over the world ACSR gained
acceptance and is still being used. All Aluminium Alloy Conductors (AAAC) made of Al-Mg-Si
alloy, first introduced in France gained popularity because of its higher strength compared to EC
grade Aluminium of equivalent size, less weight, higher corrosion resistance and non-magnetic
nature compared to ACSR. Over the years different combinations of Al, Mg, Si, have been adopted
to meet the desired strength and conductivity. The first alloys introduced were non-heat treatable.
Later, heat treatable and artificially aged conductors with still higher strength were introduced.
The application of AAAC has been widely accepted in India. However, instances of corrosion
damage are reported despite the fact that all the quality norms are followed for the procurement of
conductors. This paper deals with various aspects of corrosion damage occurred to the conductors.
The damage occurred to the conductors have been investigated from the point of view of its
composition, manufacturing process, strength, resistance to corrosion and method of storage.
Ferroelectric Nanomaterials Through Mechano-Chemical Processing
S. Vynatheya, S. Seetharamu and Parvati Ramaswamy
Ferroelectric perovskite powders pertaining to various oxides were prepared by using mechanochemical processing followed by heating at low temperatures (200°C–400°C). The complete process
yielded nano (~ 50 nm) to submicron (up to 0.3 μm) sized powders of well formed compound
indicating complete formation of the desired phase. It has been shown that mechano-chemical
activation substantially increases the solid - state chemical reactions at the milling temperatures.
During milling, the reaction zones have not only increased as the particle and grain sizes have
decreased, product phases have also formed at low temperatures with smaller amount of external
energy compared to conventional processing methods.
Vol. l. No. l, September 2004
10. Energy Services in International Trade: Implications for a Developing Country like
B.S.K. Naidu
Energy must be available, accessible and affordable. But let us remind ourselves that it varies
amongst countries and regions and in spite of the growing awareness of environmental implications,
the 20th century has ended with the world’s commercial energy mix as Fossil fuels - 85 per cent,
Hydro - 9 per cent, Nuclear - 4 per cent, New renewables - 2 per cent. Nearly two billion people
(one third of the world’s population) have no access to modern commercial energy forms such as
electricity and oil.
11. Combustion Characterization of a Pulverized Coal 210 MW Boiler through
Computational Fluid Dynamics Approach
V. Saravanan, Ramakrishna and S. Seetharamu
This study consists of the numerical simulation (based on commercial CFD code) of the flow and
combustion processes that take place in the furnace of a 210 MW pulverized coal utility boiler. The
modeling has been done for various conditions like coal mass flow and particle size distribution
from different burner levels. The modeling has also been carried out for different burner tilt angles.
The effects of these conditions in terms of unburnts, heat flux distribution, emissions, actual heat
energy utilized in the boiler, heat loss in terms of unburnts and heat carried away by flue gas have
been brought out in this paper.
12. Effect of Ash on the Efficiency and Capacity of Coal Fired Thermal Power plants
M. Siddhartha Bhatt
This paper reports the effect of ash content in raw coal on the energy performance of coal fired
thermal power plants of capacity range 30-500 MW. It also gives the extent of capacity reduction
in equipment due to firing of coals with higher ash contents.
The effects of variation of ash in coal from 6% (taken as standard) up to 75% (extreme) on component
performance are studied and overall unit performance is quantified based on experimental data and
performance simulation. When the ash content increases from 6% to 57% and above, the effects
on the system (without fuel oil support) are: (a) efficiency of boiler fans drop by 22-27%, (b) drum
mills show an increase in SEC of 115% while ball-race mills and bowl mills show an increase in
SEC of 30%, (c) ID, FD and PA fans shown an increase in SEC of around 30%, 6-14% and 2-7%
respectively, (d) the gross and net overall efficiencies are reduced to 77% and 66% of their original
values, (e) ratio of the specific fuel consumption at a given ash content to that at standard ash of
6% increases from 1 to 10, and (f) SFCgross increases from 0.35 to 3.0.
When the ash content of coal goes beyond 57%, limitations in combustion space and flow arise
and beyond this the unit has to be operated only at part load. When the ash in coal exceeds 75%,
its UHV is reduced to zero.
Vol. l. No. l, September 2004
13. Life Assessment of Super Heater and Reheater Tubes through Steam Side Oxide Scale
Measurements-CPRI Experience
R.K. Kumar, V.N. Nagaraja Rao and S. Seetharamu
High temperature pressure parts of boilers where in creep is the major damage mechanism, are
required to be assessed periodically (after 100000 hrs) for remaining life. Creep life estimation
could be made by destructive and non destructive techniques. This paper highlights the use of
ultrasonic technique for assessment of creep life of SH/RH tubes by in-situ steam side oxide scale
measurement. The scope for future studies are also given in the paper.
14. Turn Fault Characteristics Of Transformer Using Transfer Function Method
Pradeep M. Nirgude, B. Gunasekaran, Channakeshava, A.D. Rajkumar and B.P. Singh
The paper presents the transfer function method used to study the turn fault characteristics behavior
of a 100 MVA, 220/66/11 kV transformer. The whole transformer is modeled by subdividing into
44 sections and represented by self-inductance, mutual inductance and capacitance parameters.
The current in the neutral is computed by solving the network for applied impulse voltage. The
transfer function is obtained for various turn faults simulated by reducing the number of turns in the
electrical data for a given section. The location of the turn faults along the height of the winding
is varied to study the characteristics behavior of the transformer by computing transfer function.
Details of modeling, simulation of turn faults, computation of neutral current, transfer function are
presented in the paper. The effect of turn fault on the characteristic changes in the transfer function
of the transformer is presented and discussed.
15. Seismic Testing of a Bamboo Based Building System
R. Ramesh Babu, K.B. Manjunath, Prabhakar Hegde, R. Panneer Selvam, Paul Follet, H.N.
Jagadeesh and H.G. Reddy
Bamboo grows in abundance in the earth’s subtropical and tropical zones, where the majority of
earthquake hazards occur regularly. Bamboo is gaining in popularity as an earthquake-mitigating
material because engineers are beginning to understand its structural properties. A research project
has been taken up to investigate the practical use of bamboo in inexpensive, earthquake-resistant
structures. Seismic tests were carried out on a full scale one room bamboo house using triaxial
shaker system to evaluate its adequacy in resisting earthquake loads and to study its performance
during earthquake.
Vol. 2, No. 1, March 2005
THE JOURNAL OF CPRI - Vol. 2, No. 1, March 2005
Feasibility Studies on Upgradation of Existing Transmission Lines - Mechanical
M. Selvaraj and P. Muniyappa
Increase in demand for electrical power necessitates enhancement of power transmission capability
of the existing lines. This increased demand for power can be met by up-rating and/or up-grading,
the existing lines under specific constraints. In this paper, the work done by CPRI for up-grading a
few existing transmission lines into possible higher voltages for power utilities are discussed.
Towards Bench Marking of Gross Unit Heat Rate in Coal Fired Thermal Power
Stations - A Rational Approach
M. Siddhartha Bhatt and B.H. Narayana
The heat rate (HR) is the coupling factor or the transfer function relating the coal consumption to
the electric generation. Presently there are knowledge gaps in the designing of energy performance
indices and evaluating the performance of operating thermal power units using these. This paper
reports a new method for estimation of gross unit HR and thereafter the HRs of the station and the
generating company (GENCO) by a concept called as rational HR. The rational HR, which forms
the basis for performance standards, is arrived at by calculating the design HR and adding the
deviations on various allowable counts to the design value. The HR so arrived from this procedure
can be used for the purpose of evolving a standard HR and ultimately for benchmarking of HR
depending on age, operating, etc., for setting up efficiency standards. For a typical 210 MW unit,
typically, a deviation of 281 kcal/kWh can be allowed from the design gross unit HR for fixing the
standard bench mark. Another conclusion from the study is that the calorific value (CV) of the coal
should be on As Fired Basis (AFB) and not on Air Dried Basis (ADB).
Evaluation of Structural Properties of Porcelain Materials Using NDE Methods
P. Sampathkumaran, S. Vynatheya, R.K. Kumar, S. Seetharamu,
Vishwas I. Bhat and K.R. Hebbar
Porcelain products have gained popularity over the years in a variety of field applications ranging
from electrical insulation to dinnerware. The percentage of a-alumina and α-quartz in porcelain
material is said to have significant effect on its structural properties. In this work, three grades of
porcelain (ceramic) samples with varying alumina and quartz contents have been studied with a view
to correlate their material constants with composition. Owing to the anisotropy and brittleness; the
evaluation of elastic properties of such materials through conventional technique is quite involved
and results in a larger scatter. This work reports the evaluation of material constants by the impulse
excitation (sonic) method. To verify the accuracy of the method, tests were carried out on a standard
aluminum sample, and the results are compared with the values given in literature as well as the
values found by the ultrasonic method. The poisson’s ratio has been estimated by simulating the
natural frequencies by finite element analysis (FEA) and selecting the value having least mean
square error in comparison with the experimental value. It is found that an increase in α-alumina
and decrease in α-quartz lead to a considerable improvement in the elastic constant.
Vol. 2, No. 1, March 2005
Dissolved Gas Analysis of Transformer Oil using Novel Multiple Gas Extraction
R. Panneer Selvam, D. Ravindra, H.C. Keshavamurthy and G.R. Viswanath
Dissolved Gas Analysis (DGA) is the technique used to find the internal faults in the transformers
at the incipient stage. Since faults are detected at the initial stage, repair work can be planned at a
convenient time based on the severity of faults and major failure of transformers can be avoided.
This in turn results in improving the reliability of power supply. Liquid Dielectrics Laboratory
(LDL) of Central Power Research Institute (CPRI) is pioneer in DGA technique involved in
monitoring of transformers internal condition for the past two decades. LDL monitors more than
1000 transformers every year for its internal condition. New multiple gas extraction system was
designed and fabricated at LDL, which works on the topler pump principle. This Novel Multiple
Gas Extraction Apparatus is highly efficient system which can extract 98% of dissolved gases
in transformer oil. Also Multiple Extraction Apparatus is simple, compact, easy to operate and
requires less mercury.
Sliding Wear Behaviour of Glass-Epoxy Composite System
P. Thomas, P. Sampathkumaran, R.K. Kumar and S. Seetharamu
Inexpensive electrical (E) grade fiberglass composites are in use today in a wide variety of
applications from consumer products such as fiberglass boats to aerospace components. Fiber
composites possess high strength to weight and stiffness to weight ratios. In the present work, the
G-E composites were fabricated using a hand lay up technique hy stacking two different fabrics in
alternate sequences. The slide wear loss measurements were carried out using a pin on disc set up
for four different sliding distances and loads with a view to monitor the effect of these parameters
on the wear loss. Differing responses in the wear behaviour were noticed with respect to the load
and sliding distance parameters employed for the G-E system. These wear data were well supported
by Scanning Electron Microscopic (SEM) pictures.
Pyridine based Heterocycles as Possible Curing Agents for Epoxy Resin System
P. V. Reddy, Sakuntala Samuelson and N. M. Nanje Gowda
Pyridine based heterocycles 2-(4-pyridyl) benzimidazole, 2,6-bis (benzimidazol-2-yl) pyridine,
dichloro di[2,6-bis(2-benzimidazyl)pyridine]nickel(II), and dichloro di[2,6-bis(2-benzimidazyl)
pyridine] cobalt(II) have been synthesized, characterized and evaluated for possible curing of
anhydride curable epoxy resin system. It appears that the rate of curing is found to increase with
enhanced concentrations of these heterocycles. There is an appreciable reduction in the cure gel
time with the enhanced concentration of heterocycles. Kinetic studies based on thermo analytical
techniques reveal that the cure times of these epoxy resin systems decrease with increase in
temperature and also with enhanced concentration. The values obtained are comparable to those
systems with commercial accelerator. It is also observed that the electrical properties of the cured
epoxy system in presence of the heterocycles show lower loss factor values than that corresponding
to metal complexes.
Vol. 2, No. 1, March 2005
Effect of Surface Coatings on Erosion Behaviour of Hydroturbine Steels
D.B. Goel, Neeraj K Sharma, Jadav Jhansi Bai and Navneet Arora
Investigations have been carried out on the erosion behaviour of surface coated steels which find
application in the fabrication of under water parts in hydroelectric projects. Three different grades
of austenitic stainless steels (AISI 304, 26/10 and 21-4-N) and one grade of martensitic steel (13/4)
have been used as substrate materials. Three types of coating substances, viz. (i) WC-Co-Cr, (ii)
Cr3C2-NiCr and (iii) A1203 have been coated on steel substrates using (i) Detonation Gun and (ii)
Plasma Spray techniques. A sand blast type test rig has been designed and fabricated for conducting
erosion tests on substrates and surface coated specimens. The erosion behaviour has been analyzed
on the basis of met alio graphic examination (optical and scanning electron microscopic) and other
parameters like hardness and porosity contents in surface coatings.
Status and Future Directions of Electric Power Industry Restructuring in India
S.N. Singh and S.C. Srivastava
Power industry restructuring, around the world, has strongly influenced the Asian power industry as
well. Restructuring of Indian power industry introduced a limited level of competition since 1991
at generation level by allowing participation of Independent Power Producers (IPPs). The new
Electricity Act 2003 provides a framework for allowing competition in stages at different levels. It
is felt that the prevailing condition in the country is good only for wholesale competition at present
and not for the retail competition. This paper analyzes the current status of Indian power sector and
suggests a possible model for establishing competitive electricity market in the country.
Selection of Features for Security Evaluation of Power System using ANN
K.R. Niazi, C.M. Arora and S.L. Surana
This paper presents an Artificial Neural Network (ANN) based method for on-line security
evaluation of power systems. A large number of features (variables) characterize a given power
system. The ANN can not be trained with complete set of power system variables (features) due to
high dimensionality; therefore, feature selection is necessary to make the approach feasible. This
paper uses a divergence based feature selection algorithm to select best possible size of neural
training features. A comparison of different feature selection methods is presented. The effect of
number of features and size of training set on the performance of ANN has also been investigated.
The method has been applied on an IEEE test system and the results demonstrate the potential
of the proposed method for on-line security evaluation of power systems even under changing
topological conditions.
Vol. 2, No. 1, March 2005
10. Power System Stabilizers in Power Systems
P.V. Bala Subramanyam
The Power System Stabilizer (PSS) is an optional control that is part of the excitation system for
generator control. The PSS acts to modulate the generator field voltage to damp electrical powerspeed oscillations. It is desirable to ensure that the generator controls are equipped to support
transmission system reliability by enhancing the excitation controls. The Power System Stabilizer
(PSS) provides supplementary control that improves dynamic stability by increasing damping of
power swing oscillations. Excitation systems with high gain and fast response times greatly aid
transient stability (synchronizing torque), but at the same time tend to reduce small signal stability
(damping torque). The main objective of the PSS is to increase damping of generator rotor angle
swings, which can occur in a broad range of frequencies in the power system.
11. Facts about Energy Saving in Lighting
H R Sreenatha Rao & M S Divekar
For conventional lighting for many decades, incandescent bulbs have been used widely. The
incandescent lamp was first developed by the great scientist Thomas Alva Edison. Fluorescent lamp
(FL) or popularly known as Tube light (TL) was developed much later. Subsequently Compact
Fluorescent lamps (CFL) were developed. Both these are low pressure gas discharge tubes. For the
purpose of this article, the discussion will be restricted to these three varieties of lamps only, which
are used for general lighting for normal use. CFL is nothing but a FL bent in some form. The very
purpose of developing a CFL was to see that it replaces an incandescent lamp, particularly where
space is a constraint in existing fittings. (It is extremely important to know this rider). Hence, where
space is not a constraint FL is far more efficient than CFL!!! Hence in all new applications FL is to
be preferred to CFL, if one is particularly concerned about energy efficiency, Green environ ment.
The purpose of this article is to explain this fact.
12. Computational Models for Residual Creep Life Prediction of Power Plant
G.S. Grewal and A.K. Singh
In high temperature steam tubing in power plants, one mechanism by which a significant temperature
rise can occur is by the growth of a thermally insulating oxide film on its steam side surface. In
the present paper, an elegantly simple and computationally efficient technique is presented for
predicting the residual creep life of steel components subjected to continual steam side oxide film
growth. Similarly, fabrication of high temperature power plant components involves extensive use of
welding as the fabrication process of choice. Naturally, issues related to the creep life of weldments
have to be seriously addressed for safe & continual operation of the welded plant component.
Unfortunately, a typical weldment in an engineering structure is a zone of complex microstructural
gradation comprising of a number of distinct sub-zones with distinct meso-scale and micro-scale
morphology of the phases and (even) chemistry and its creep life prediction presents considerable
challenges. The present paper presents a stochastic algorithm, which can be used for developing
experimental creep-cavitation intensity versus residual life correlations for welded structures. Apart
from estimates of the residual life in a mean field sense, the model can be used for predicting the
reliability of the plant component in a rigorous probabilistic setting.
Vol. 2, No. 1, March 2005
13. Assessment of Strength of Indian Transmission System
Mata Prasad FNAE
The growth of power generation in India since 1947 appear to be quite satisfactory rising from
less than 1400 MW to 108,000 MW keeping in view the resources made available. The generation
expansion however has so far not been able to meet the load demand with the result that the power
shortage has been around 10%. The Five Year Plans laid emphasis on generation expansion at the
rate of about 45–50,000 MW in the five year plan period aiming for generation expansion at the rate
of 10,000 MW per year. The achievement has been just fifty percent of what was planned specially
in the last two five year Plan period.
Vol. 2, No. 2, September 2005
THE JOURNAL OF CPRI - Vol. 2, No. 2, September 2005
Fuzzy Logic Approach for Solving Unit Commitment Problem in Utility System
S. Chenthur Pandian, K. Duraiswamy and C. Christober Asir Rajan
Unit Commitment (UC) in power systems refers to the optimization problems for determining
the ON/OFF states of generating units that minimize the operating cost for a given time. In this
paper; Load Capacity of Generators (LCG), Fuel Cost (FC) and Start-Up Cost (SUP) are taken
as fuzzy inputs and the Production Cost (PRC) is taken as an output. The input variable LCG has
been divided into five triangular membership functions. They are Low, Below Average, Average,
Above Average and High. The other two input variables FC and SUP have been divided into three
triangular membership functions. They are Low, Medium and High. The Production Cost (PRC)
as an output has been divided into five triangular membership functions. They are Low, Below
Average, Average, Above Average and High. Case studies have been performed for State Electricity
System (SES) which is known as utility system in this paper. By implementing fuzzy logic the
production cost is found out. These values are compared with the Production Cost of conventional
Dynamic Programming (DP). It is observed that the fuzzy based production cost is economical
than the conventional DP method. Practical calculation and results are taken for simulation and the
simulation has been performed by using the developed software in MATLAB package.
Fretting Wear and Fretting Fatigue Failures in Power Plant Components: A Review
Aravind Vadiraj and M. Kamaraj
Fretting damage is observed when two mating bodies under contact pressure experience micron
level tangential relative motion. Both fretting wear and fretting fatigue induce damage causing
premature degradation of the materials. Power plant components have shown failures due to fretting
induced damage. This article gives details about the possible locations of fretting damage, different
materials used in power generation machinery, failure mechanisms and prevention measures for
fretting wear and fretting fatigue failures in power plant components.
Multi-machine Wind Diesel Power System with a Superconducting Magnetic Energy
Storage Unit at the Load Bus
Shameem Ahmad Lone and Mairaj ud-din Mufti
Wind diesel power systems are characterized by low inertia, low damping and poor reactive power
support. These systems are, therefore, very prone to wind power variation, load disturbances and
other perturbations. A short-term energy storage unit is generally required to achieve prescribed
power quality levels in these systems. In this paper, installation of a Superconducting Magnetic
Energy Storage (SMES) unit at the load bus of such a system is proposed. A control strategy based
on fuzzy logic is used to modulate the exchange of real and reactive powers between the load
bus and the SMES unit in four quadrants of P-Q plane. The effectiveness of the SMES unit is
investigated for various case studies using simulation studies.
Vol. 2, No. 2, September 2005
Solar Cooling Systems: An Overview
G.S.V.L. Narasimham and M.V. Krishna Murthy
Utilisation of solar energy for the production of cold by adapting different techniques is discussed. For
the cases of vapour compression, vapour absorption, vapour jet and dehumidification-humidification
systems, the various aspects such as state of the art, description of typical systems, performance
characteristics and design considerations are discussed taking into account the suitability and
limitations associated with solar energy collection and storage devices. A comparative study of the
different refrigeration systems suitable for solar energy applications is made.
Application of Charge Simulation Method (CSM) and Artificial Neural Network
(ANN) in determining Corona Power Loss
N. Roy, Nabamita Roy and K. Bhattacharya
In this paper, a numerical method has been employed for evaluating the Corona Power Loss (CPL)
in a single-phase AC transmission line. In this method, the emission of ions is considered to take
place from the wire when the field on the wire surface exceeds the onset value. The ion emission
stops when the system voltage reaches the corona ending value. Both the charges of the conductor
and the space charges are simulated by discrete line charges. The Charge Simulation Method (CSM)
has been applied to compute the charge emission from the coronating wire during corona periods
over, both the positive and negative, half cycles. The simulated line charges are displaced away
from and back to the wire by the prevailing AC field, as computed by the CSM, with subsequent
recombination between the outgoing and returning line charges of opposite polarities. The ion
emission is considered to reach a steady state after several AC cycles and the CPL is computed
when the ion emission reaches a steady state. The computed CPL agrees well with the one measured
experimentally. The computed values of CPL and the corresponding applied voltages are fed to an
Artificial Neural Network (ANN) for training, as the output and input vectors, respectively. After
successful completion of the training, CPL corresponding to any voltage lying within the range
of input pattern vector is obtained from the ANN. This corona power obtained from ANN is then
compared with the value obtained using CSM and the error is well within the limit.
Vol. 2, No. 2, September 2005
Influence of Moisture Absorption on Electrical Characteristics of Glass-Epoxy
Polymer Composite System
P. Thomas, P. Sampathkumaran, S. Seetharamu, K. Dwarakanath and Kishore
The Fibre Reinforced Polymer (FRP) composites, which are being increasingly used in electrical
insulation, should withstand electrical stresses under moist environment. The composites get
deteriorated due to the moisture absorption in the working environment. During the moisture
absorption process, water ingression into the interior including the polymer reinforcement interface
region occurs causing degradation. This significantly contributes to the deterioration of electrical
characteristics. To study these, composites having three different volume fractions of fibres were
fabricated using the hand lay up technique by stacking two different fabrics, chiefly, Woven Roving
(WR) and Chopped Strand Mat (CSM). For one set, the top layer was made of CSM and the bottom
WR (Composite 1). For the next two, CSM layers were both at the top and bottom while the number
of WR that followed these cover layers was either two, in one case, (Composite 2), or, three in the
other (Composite 3). The dielectric dissipation factor, dielectric constant and insulation resistance
measurements were carried out on these composites at room temperature and after subjecting to
water absorption up to 96 h. The weight gain for all three types of composites show a linear
increasing trend up to 72 h and thereafter a trend for saturation sets in. Further, it is seen that the
dielectric dissipation factor and dielectric constant of the composites increase with increase in the
water absorption duration and correspondingly the insulation resistance shows a deteriorating trend.
Among the three composites studied, Composite 2 having highest fibre content and, hence, the least
matrix content shows better performance compared to composites 1 and 3.
Transformer Diagnostic Testing by SFRA
Ashok Kumar Yadav and Subhash C. Taneja
High short circuit currents can lead to deformations and displacements of the transformer windings
due to mechanical forces. The paper discusses SFRA — a modern diagnostic method which identifies
such pre-damaged power transformers which have better sensitivity towards changes in the winding
geometry. Changes in the geometric configuration alter the impedance network, and in turn alter
the transfer function. This enables a wide range of failure modes to be identified. SFRA analysis of
post-failure of transformers without oil, bushing and previous complimentary test results is being
Vol. 2, No. 2, September 2005
Mechanical Property Evaluation of Polyurethane based Epoxy and Polyester Alloys
Rajshekhar Algood, Prashanth T, S C Sharma and Syed Akeel Ahmed
Polymers have extended the horizon of engineering materials beyond the realm of natural combinations
and into the realm of man-made ones. Polyurethane polymers formed by interpenetrating two or
more sorts of cross-linked polymers through physical or chemical methods have gained more and
more attention in recent years. In the present investigation, polyurethane alloys were prepared by
volumetric mixing of the constituent resins. Polyurethane-polyester alloys (PPA) and polyurethaneepoxy alloys (PEA) were prepared, with polyester/epoxy varying from 10 to 20-volume fraction
in steps of 5-volume fraction. The polymerization processes were traced through morphology.
Mechanical properties of the alloy systems were studied through tensile strength, hardness and
SEM studies. The results of the study indicated that as the polyester or epoxy content in the alloys
was increased; there was a remarkable increase in the Young’s modulus, ultimate tensile strength
and hardness. The PPA specimens showed superior properties to that of PEA and polyurethane
specimens. This study brings out the mechanical property evaluation of the above mentioned
polymers. It is thereby intended to utilize these results further by alloying the best out of the three
polymers (Polyurethane) with E-Glass, suitable to be cast into Braided Tubes used extensively for
space applications.
Recent trends in High Voltage Engineering Research
A.K. Tripathy and K.N. Ravi
Higher and higher voltage for power transmission has been a fascinating subject of research after
the advantages of EHV transmission was realized nearly a century back. Centres for EHV and
UHV research in the early seventies and eighties were the IREQ of Canada, AEP of USA, CESI of
Italy, The BPA of USA, ASEA of Sweden, SIEMENS of Germany and the High Voltage Research
Centers at St. Petersburg, Russia. UHV levels up to 1200 kV and HVDC Voltage up to +750 kV
were explored and the behaviour was studied.
The research on UHV could not be supported for long because it was realized that for UHV lines
carrying beyond 2000 to 3000 MW of power, reliability was a major question. The teething problems
with early 765 kV AEP and HQI lines, particularly the reactive power problems and switching O/V
problems were deterrent to introduction of very high voltage in a weak grid. The reliability of the
lines depended on good insulators, tower design, arrester protection, high temperature conductors
which were not perfected at those times.
All over the world, 345kV, 400 kV, 500 kV and 765 kV emerged as standard voltages in AC
transmission and +500 kV and +600 kV for DC transmission. As equipments of proven design and
reliability were produced by manufacturers, these voltage levels were stabilized.
The interest in introducing +800 kV DC and 1000 kV AC has again surfaced as the system is
growing, and level of confidence in +600kV DC and 765kV AC is increasing.
In this paper, an attempt has been made to study the major research areas in High Voltage discipline.
The source of information is publication in journals and available information from suppliers, test
houses and institutes.
Vol. 3, No. 1, September 2006
THE JOURNAL OF CPRI - Vol. 3, No. 1, September 2006
Development of a New Technique for Measurement of Coal Flow
M. Sidhartha Bhatt and B.H. Narayana
This paper reports the development of two novel products—a coal flow simulator and an instrument
for coal flow measurement.
Uniform pulverized coal flow is simulated in a horizontal pipe of 200 mm diameter and 2000
mm length with a capacity 50-300 kg/h at an air to fuel ratio of 1.5-2.5 kg of air/kg of fuel with
a maximum of 20% moisture. Coal is fed from a hopper and the flow is simulated in a tube. The
calibrated coal flow is achieved through a vibratory feeder with a convergent-divergent nozzle
which is pneumatically activated from a compressed air source. The simulator is isolated from
vibrations and flow measurement/visual imaging is possible through air-curtained ports. The loss
of coal to the environment at the end of the simulation zone is less than 0.05%. The non-reactive,
non-mixing type, PC compatible portable instrument for measurement of pulverized coal flow uses
a new sensing tool-laser through laser beam interception for flow through circular pipes of 0.3-0.5
m diameter. It is capable of measuring pulverized coal flows of the order of 0-150 kg/h (for a pipe
of 200 mm diameter) in the range of 0-5000 kg/m2/h. The laser-through beam sensor is mounted
across the flow without contact with the coal. The opacity offered by the pulverized coal flowing
in the pipe to the radiation emitted by the transmitter is proportionate to its mass flow. The receiver
induces a voltage proportional to the intensity of residual light received which is calibrated based
on the mass flow rate. The induced voltage is stepped down, processed, digitized and acquired
through Rs. 485 data protocol. The standard coal that can be measured is sized at 70% of the mass
below 75 μm size. The normal primary air to fuel ratio is around 1.5-2.2 kg of air/kg of coal. The
instrument is insensitive to moisture contents upto 10%. For moisture contents above 10% and for
fineness and air/fuel ratio different from the above, calibration of the instrument is required. The
instrument has an accuracy of 0.5% and the response time is 0.5 ms for standard coal. It operates
on a power source of 230 V AC (100 W) and is useful for field applications as a portable instrument
(0.5 m x 0.5 m x 0.5 m).
System Studies of Grid Disturbances Encountered in Kashmir Valley Power System
During Islanding Operation Subsequent to Link Failure with Northern Regional Grid
in February, 2005
N.A. Laway, Wasim Aziz Shah and Ghulam Nabi Shah
The Northern Regional (NR) Grid consists of generation and transmission power utilities of the states
of Jammu and Kashmir, Punjab, Himachal Pradesh, Haryana, Rajasthan, Delhi and Uttaranchal, and
the central utilities viz Powergrid, NHPC, NTPC. The Regional Electricity Board of J & K, Power
Development Department (PDD) and Power Grid experienced several major grid disturbances in
the recent past resulting in cascade tripping of 220 kV lines and generating units. This resulted
in separation of grid into several isolated parts with disruption of power supply. This paper deals
with the analysis of the grid disturbance that occurred on 12 Feburary, 2005. In this paper, main
emphasis is given to abnormal behaviour of generating units at Uri-I (NHPC) generating station at
Uri, Baramulla (Kashmir).
Vol. 3, No. 1, September 2006
Simulation and Comparison of the STC (Synthetic Test Circuit) for thyristor valves
for HVDC by the software PSCAD
Zhou Huigao, Xu Fan, Hu Zhilong, Huang Chao, Zheng Jun, Li Yanming
In recent years, HVDC technology has been developing very fast with the increasing demand
of electric power in China. It is very important to build up a test circuit for operational test of
thyristors in order to ensure the safety and reliability of HVDC system. Today there are only two
test laboratories in the world which are capable of undertaking the synthetic test—ABB in Sweden
and Siemens in Germany. After comparing and studying the two circuits, a new model is set up for
analysis and simulation, and all the test duties which are required in IEC 60700-1 are successfully
achieved by the use of PSCAD.
In this paper, the principle of the circuit and the simulation results are presented. It is very helpful
in building up the STC of China on its own.
Fuzzy Identification and Modeling of an Intelligent Controller for Adaptive Control of
Reactive Power in a Utility System Using ANFIS
S. Thangavel, V. Palanisamy, K. Duraiswamy and S. Chenthur Pandian
Modern power systems tend to be very complex not only due to increasing demand for quality
power, but also on account of extensive interconnection and increasing dependence on control for
utilization of power with optimum losses and cost. Either conventional controller or intelligent
controller can be used to get the adaptiveness in the parameters of the system considered. As
the conventional controllers are non-interactive and cannot compensate for parameter variation,
control engineers are moving to intelligent controllers for adaptive control. Since any power system
does not have proper modeling and shows non-linear behaviour, it requires a continuous expert
knowledge for its control. Hence fuzzy logic controllers are the most suitable intelligent tools for
the adaptiveness of the power system. Here the Adaptive Neuro Fuzzy Inference System (ANFIS)
is used to obtain the adaptiveness in the system. The adaptive control of reactive power in a utility
system has been justified in this paper.
Performance Analysis of Unified Power Flow Controller using Fuzzy-PI Control
S. K. Srivastava, K.G. Upadhyay and S.N. Singh
The Unified Power Flow Controller (UPFC) is one of the most versatile FACTS devices that has
unique capability of independently controlling the real and reactive power flows, in addition to
regulating the system bus voltage. This paper presents performance analysis of Unified Power Flow
Controller based on the two-axis theory. Based on this analysis a new Fuzzy-PI controller has been
proposed to improve the system performance. The controller rules are structured depending upon
the relationship between series inserted voltage arid the desired changes in real/reactive power
flow in the power system. The effects of different controllers along with parameters of series
transformer and transmission line have been investigated through developed control block model
in SIMULINK. The effectiveness of the proposed scheme is demonstrated by case studies.
Vol. 3, No. 1, September 2006
Compatibilization of Biodegradable Tapioca Starch/LDPE Blends to obtain Products
to be used for Short Term Packaging Applications: Dealing with Waste Polyethylene
from the Power Sector
R.R.N. Sailaja and S. Seetharamu
LDPE has been blended with plasticized Tapioca Starch (TS) with starch loadings varying from 20%
to 50%. As the starch loading increases, the mechanical properties reduce and drop down to nearly
30% of that of neat LDPE. In order to enhance the adhesion between starch and LDPE, itaconic
acid (naturally obtained during fermentation of sugars) was grafted onto LDPE to obtain LDPEg-itaconic acid and used as compatibilizer. Addition of this compatibilizer substantially improved
the mechanical properties, especially the tensile strength (at par with that of virgin LDPE) and
tensile modulus TS loading of 40%. Scanning electron micrographs of the blend specimens also
supported the above observation. Thermo gravimetric analysis was carried out to assess the thermal
degradation of blends.
This study aims at a possibility of utilization of post consumer polyethylene waste for producing
biodegradable blends.
Influence of Load on the Friction and Wear Behaviour in Glass-Epoxy Composite
B. Suresha, G. Chandramohan, P. Sampathkumaran, R.K. Kumar,
S. Seetharamu and C.H. Sathish
Polymeric composites are steadily gaining importance in recent times for industrial applications
and their increase in the use calls for a better understanding of their behaviour under working
environments. Friction and wear are considered two important parameters, that govern the
tribological behaviour. In this study, the friction and wear characteristics of E-glass-Epoxy (G-E)
and graphite filler of two different levels in G-E composites were experimentally investigated using
Pin-on-Disc setup at varied loads and sliding velocities. From this investigation, it is found that
7.5 wt % graphite filled G-E composite system shows least coefficient of friction and highest wear
resistance compared to the plain G-E composite system irrespective of the load/speed adopted.
Further, this paper highlights the Scanning Electron Microscopic (SEM) observations with respect
to their wear behaviour for interpretation of the data. The SEM pictures of the highest graphite
filled sample corroborate the wear data thus complimenting each other.
SA based Genetic Algorithm for Reactive Power Optimization
B. Bhattacharya and S.K. Goswami
Genetic Algorithm (GA) is hybridized with the Simulated Annealing (SA) technique while
solving the reactive power optimization problem. This hybrid Genetic Algorithm is used for both
optimum planning and dispatch of reactive Var Sources. SA used along with GA for reactive power
optimization yields better solution than GA. First a focus zone of the search space is identified by
using the SA technique and then Genetic Algorithm (GA) with population initialized around that
focus is applied to obtain the optimum.
Vol. 3, No. 1, September 2006
Risk Assessment for Catastrophic Failures in Power Systems
J. Hazra and A.K. Sinha
This paper presents a method for identifying sequences of events (Worms) leading to catastrophic
failures of power systems. Chains of events leading to catastrophic failures are identified using two
indices (i) Severity Index (ii) Risk Index. The first method considers only the consequences of an
event whereas the second one considers the consequence of an event along with the probability
of occurrence of that event. Risk index condenses both probability and severity of any event. This
paper also considers the probability of hidden failure of exposed lines for calculating the risk
10. A New Approach to the Determination of Optimal Sizes and Optimal Locations of
SVC Devices for Voltage Profile Improvement of a Power System
D. Sathaiah, E. Akila and B. Andal
A new systematic method for determination of optimal sizes as well as optimal locations of SVC
devices for voltage stability and voltage profile improvement of a power system is presented. The
proposed method is based on static voltage stability criterion using the well-known L-index. The
highest value of L-index indicates the most critical bus in the system. The proposed new approach
has been tested on IEEE 14-bus test system and IEEE 30-bus test system under different operating
conditions. The results are found to be quite satisfactory.
11. Modular Power Supply for Telecom Application (48 V/100 A)
T. Thandapani and R. Arumugam
This paper describes the practical aspects of building modular power supply for telecom application.
The latest requirements of the telecom industry calls for high efficient power supplies capable of
handling large input voltage variation. The power supplies are required to produce high input power
factor and low input current harmonic distortion. In addition to the above, the power supplies
should be of light weight, smaller in dimension and modular in construction.
Although there are lot of papers on Power Factor Correction (PFC) circuits, soft switching converters,
Active current sharing circuits, RFI/EMI etc., none or very few papers provide a complete solution
for an industrial power supply. In this paper, an attempt is made to provide a complete, economical
and a viable solution for building a Telecom power supply which meets or exceeds the requirements
of the telecom industry. A three-phase converter using three single-phase modules connected in
parallel is discussed. Each single-phase module has an active power factor correction circuit on
the front end followed by a high efficient resonant zero voltage switched DC-DC Converter circuit
along with an active current sharing circuit for sharing the current between the modules equally.
This current sharing circuit requires only a single wire for communication between the modules.
Vol. 3, No. 2, March 2007
THE JOURNAL OF CPRI - Vol. 3, No. 2, March 2007
Development of a Silicone Composition for High Voltage Insulator Applications
K. Praveen, M.N. Dinesh, P.V. Reddy and N. Vasudev
Silicone rubber and their alloys have good high voltage insulation properties with excellent outdoor
usability. The hydrophobicity of the surface is well maintained even in wet conditions as low
molecular weight fluids diffuse out to the surface. In the present work, trihydrated alumina content
in the silicone compositions has been varied with other additives and electrical properties namely
tracking and erosion, corona and salt-fog were studied. The mechanical properties namely tensile
strength, elongation and hardness were evaluated. The Oxidative Induction Time (OIT) test was
conducted to determine the oxidative stability of the insulation. The SEM analysis was carried out
to study the filler distribution in the polymer matrix.
Frequency Response Analysis for Detecting Winding Displacement and Deformation
in Power Transformers without Reference Fingerprints
Pradeep M. Nirgude, D. Ashokaraju, A.D. Rajkumar and B.P. Singh
The paper presents the results and analysis of the experimental work carried out to apply construction
based and type-based approach to interpret Frequency Response Analysis (FRA) measurement
data. Influence of the tap changer position on the FRA measurements is analyzed. Results of onsite
FRA measurements carried out on two identical transformers with an emphasis on the detection of
mechanical winding deformation without fingerprints are presented and discussed.
Application of Hopfield Neural Network and Dynamic Programming to Unit
S. Senthil Kumar and V. Palanisamy
This paper develops a new Dynamic Programming based direct computation Hopfield method for
solving short term Unit Commitment (UC) problems of thermal generators. The proposed two-step
process uses a direct computation Hopfield neural network to generate Economic Dispatch (ED).
Then using Dynamic Programming (DP), the generator schedule is produced. The method employs
a linear input-output model for neurons. Formulations for solving the UC problems are explored.
Through the application of these formulations, direct computation instead of iterations for solving
the problems becomes possible. However, it has been found that the UC problem cannot be tackled
accurately within the framework of the conventional Hopfield network. Unlike the usual Hopfield
methods which select the weighting factors of the energy function by trials, the proposed method
determines the corresponding factor using formulation calculation. Hence, it is relatively easy to
apply the proposed method. The Neyveli Thermal Power Station (NTPS) unit II in India has been
considered as a case study and extensive studies have also been performed for different power
systems consisting of 10, 20 and 40 generating units. Numerical results obtained are compared with
conventional methods to reach proper unit commitment.
Vol. 3, No. 2, March 2007
Simulation of Availability-based Tariff Mechanism
K.Balaraman and Dr. T. Ananthapadmanabha
Availability-based Tariff (ABT) mechanism is in operation in India from 1st July 2002. The
introduction of ABT mechanism has revolutionized the power system operation in India and has
opened a new framework for power trading opportunities in the country. This paper provides
a mechanism for simulating ABT through a mathematical model. The simulation is carried out
for various operating conditions such as average load, light load and peak load conditions. The
behaviour of various constituents in the system operation is described.
Available Transfer Capability in Competitive Power Market: A Bibliographical
Ashwani Kumar, S.C. Srivastava and S.N. Singh
In the restructured power system, bulk power transactions are restricted by the transmission system
security and stability, and it is the responsibility of the system operators (SOs) to control the power
transactions and overloading of the transmission network beyond their loading limits. For this, a SO
has to update real time index termed as available transfer capability (ATC). This paper addresses
an up-to-date bibliographical survey on available transfer capability in the deregulated electricity
markets. There are 184 citations referenced in this bibliography. The general electronic websites
dealing with the issue of available transfer capability are also listed which are very useful to
academicians, utility engineers, policymakers and researchers in competitive electricity markets.
A Method for the Determination of Backup/Primary Relay Pairs for Coordination of
Directional Relays
N. A. Laway
A novel method is developed to determine the backup/primary relay pairs for use in relay coordination
programmes. Backup/primary relay pairs are essential for determining setting of directional
overcurrent relays and directional distance relays in a multi-loop complex power transmission
system. The algorithm developed is based upon the powerful network scanning capabilities of the
linked list type of data structure known as LINKNET. The method developed has been applied to
find the coordinating relay pairs for the IEEE 14-bus, the SPC 26-bus, the IEEE 57-bus and the
IEEE 118-bus power transmission systems with encouraging results.
Life Estimation of Boiler Straight Pipes under Creep and Fatigue Loads
A.R. Veerappan, S. Shanmugam, G. Jayaraman and S. Nagamanickam
Boiler pipe failures are the number one cause of forced outage of power generating units. The
principal damage mechanisms in high temperature pressure vessel and piping system is generally
creep-fatigue. The creep-fatigue life of straight pipes is estimated based on a transient thermomechanical analysis that has been conducted which simulates the past working conditions of straight
pipes. The straight pipe is modeled in ANSYS and the model is analysed initially with transient
conditions and subsequently with structural constraints. The maximum stress intensity is used to
determine the fatigue life fraction of the pipe while the structural analysis is done to determine the
creep life fraction of the pipe. A relationship between the life of the pipe under combined creep
and fatigue loads and the operating pressure is presented for the material SA335 P22 used for high
temperature applications.
Vol. 3, No. 2, March 2007
Optimum Location and Sizing of FACTS Device in Weak AC System with Integration
of Wind Farms
B.R. Lakshmikantha, Murugesh Mudaliar, K. Balaraman and R. Nagaraja
Wind energy is perceived to be a clean energy source available in plenty in some pockets of the
country. The key issue in harnessing the full potential lies in integrating wind energy into the
grid. In the restructured power systems, the transfer capability is presently a critical issue both
in the operating and planning stage because of increased interchanges among utilities. This paper
highlights the issues in integrating wind energy to the grid and to optimize the location of FACTS
devices with the help of L-Index technique. Performance issues related to the dynamic behaviour
of wind farms are discussed and the potential interactions between wind turbine generators and
compensation equipments are illustrated with simulated examples.
Robust Decentralized Control of Power Systems with OLTCs using Markov Jump
Parameter Theory
Hemanshu R. Pota, Germane Xavier Athanasius, Li Li and Valery Ugrinovskii
This paper addresses the problem of designing a decentralized control of interconnected power
systems, with On Load Tap Changers (OLTCs) and Static Var Compensators (SVCs), under large
changes in real and reactive loads that cause significant changes in the model parameters. Large
parameter variations are considered as change in the system mode. The decentralised design results
in a different linear state-feedback controller for each mode of operation. Adjustments due to
small changes in load, about an operating mode, are regulated by these decentralised controllers.
The controllers operate locally using the state of the subsystem itself and switch when load on
the system increases dramatically. The design is carried out within a large-scale Markov jump
parameter systems framework. In this paper, unlike other control schemes, OLTC transformers
are used to damp power-angle oscillations. Simulation results are presented to demonstrate the
performance of the designed controller.
Vol. 4, No. 1, March 2008
THE JOURNAL OF CPRI - Vol. 4, No. 1, March 2008
Characteristics of Fly Ash Cenospheres and their Effect on Pozzolanic Reactivity of
Fly Ash
K Suryanarayana, M Shekhar Kumar, M C Narasimhan and S Seetharamu
Fly ash cenospheres are particles found floating in the ash lagoons of coal fired thermal power
plants. The primary characterisation of these particles indicates that they are hollow, lightweight,
predominantly spherical and pozzolanic in character. The cenosphere content in fly ash varies
with the power plant depending on various operational parameters, and is generally estimated
at 1 % of the total fly ash generated. It is reported that the percentage of cenospheres increases
with the ash content in the coal, and decreases with the concentration of Fe2Or This indicates that
Fe2O3 is concentrated in the higher density fraction of fly ash. The cenospheres contain higher
alumina content, but lower iron content as compared to fly ash. The particle size distribution in
cenospheres again varies from plant to plant, and it is observed that a majority of the particle
fractions are below 150 flm. The density of cenospheres is very low as compared to that of fly
ash, which is due to the hollow nature of the particles. The morphology of cenospheres indicates
predominantly spherical particles as compared to fly ash particles. The pozzolanic reactivity of
fly ash generally depends on the amorphous content or glassy mineral content in them. The X-ray
diffraction curves of the fly ash cenospheres are good indicators of the amorphous character present
in the pozzolanic material. From XRD analysis results, it has been observed that the cenospheres
show higher amorphous character as compared to fly ash. These results are corroborated by the
pozzolanic reactivity tests.
Loss Reduction and Voltage Quality Improvement by Connecting Embedded
Generator—A Simulation Study by ETAP Software
S Bhattacharjee, S L Deb, A Das and B Das
An embedded generator is connected to an electrical distribution network. This network is the
conduit through which it exports the electrical energy that it produces. Since these exports can
have a significant effect on the pattern of flows in the network, it is important to check that they
do not degrade the quality of supply for the other users of the network. The present study shows
how an embedded generator can reduce losses in the network. The power flow for maximum and
minimum load conditions at different power factors with embedded generation has been studied by
ETAP software. The study also reveals the optimum condition for obtaining a better voltage profile
and maximum loss reduction with embedded generator.
Vol. 4, No. 1, March 2008
Short-term Electricity Load and Price Forecasting Techniques in Deregulated
Electricity Markets: A case study of Ontario Electricity Market
Sanjeev Kumar Aggarwal, L M Saini and Ashwani Kumar
In this paper, an electricity load and price forecasting case study of Ontario electricity market
has been presented. Major load and price drivers have been selected after performing correlation
analysis to form electricity load and price forecasting models based on a multiple linear regression
(MLR) technique. The load forecasting MLR model has been compared with a heuristic technique
and it has been proved that the MLR model is superior to the heuristic model. The effect of price
on short-term load forecasting has been studied from demand side responsiveness and it has been
shown that no major improvement has been observed by taking price as one of the input variables
in the load forecasting model. The results of MLR price forecasting model have been compared
with the results of a heuristic model and a model developed by Independent Electricity System
Operator (IESO) of Ontario electricity market. The MLR model has outperformed both the other
models. The model proposed in this paper is easy to implement and requires a lesser amount of
data as compared to IESO model. The results of the proposed model are available 24-hours ahead
of actual settlement, whereas IESO forecast is available 3-hours ahead only. Thus the proposed
model can help the participants to bid effectively in the market.
A Novel Method for Solar Water Pumping Promising Considerable Down Sizing and
Cost Reduction of PV Panels
Mrityunjaya Kappali and Uday Kumar R Y
The existing practice of water lifting in multi-storied buildings employs Top Floor Storage Method
(TFSM). In this method, considerable amounts of water is pumped to unnecessary heights, resulting
in energy wastage. This paper proposes a novel scheme “Individual Floor Storage Method (IFSM)”
[1] for Solar Photo Voltaic driven Water Pumping System (SPV-WPS) used in multi-storied buildings.
Here water is pumped to the required optimum heights, thus avoiding wastage of energy. This
means, for a particular quantity of available energy, the amount of water lifted will be more. Hence
we find that for a particular quantity of available energy and for a particular amount of water to be
lifted, the SPV panel capacity rating needs to be less. The direct consequence of this is a decrease
in the initial investment. Thus, as far as SPV-WPS is concerned, the benefit of IFSM is downsizing
of SPV panel and hence the reduced initial cost. This is a significant advantage particularly with
respect to SPV-WPS as their main demerit is high initial cost. Therefore employing IFSM for SPVWPS will go a long way in making them more acceptable to the common man. In this paper, the
SPV-WPS proposal is worked out with TFSM as well as IFSM for a two-storied house. It is found
from the initial tests that the PV panel peak power requirement is reduced by about 23% and there
is a drop of 17.5% in the overall initial cost.
Vol. 4, No. 1, March 2008
A New Control Approach for UPFC-based on State Feedback Technique
G Saravana Ilango, C Nagamani and M Lalit Kumar
This paper reports a new control approach for the Unified Power Flow Controller (UPFC) for
enhanced, dynamic and steady state performance-based on state feedback control technique. The
results of investigations are presented on the implementation of State feedback control technique in
a power transmission system incorporating UPFC. The use of state feedback control for controlling
the operation of UPFC has not been reported earlier in the literature. The objective is to achieve
effective control of the active and reactive power flows in the line, with minimum or zero dynamic
interaction between them. A simple two machine power system with a UPFC is used for the study.
The system response to the power flow commands is investigated and the effectiveness of state
feedback control is examined. Reference frame theory based mathematical models are used for
analysing the performance of the system in closed loop. Simulations are carried out using MATLAB/
SIMULINK. The results indicate an overall improvement in performance with negligible dynamic
interaction and zero steady state error, thus validating the proposed control scheme. The proposed
approach has a straight forward design and the control law structure is simple.
Investigation on Risk of Subsynchronous Resonance for Series Compensated 400 kV
Lucknow-Balia Line
J Sreedevi and Sujatha Subhash
This paper presents an analysis of Subsynchronous Resonance (SSR) for series compensated 400kV
double circuit Lucknow-Balia line planned in the northern region of India. The power system
software SIMPOW in MASTA mode is used for the analysis. The paper demonstrates the usage
of an interesting feature present in the software-switching a large power system study between
fundamental frequency and instantaneous value mode at any time during the simulation. The SSR
consequences for large disturbances have been simulated and the results are presented along with
Development of a Fast Activating Magnesium-based Solid-State Hydrogen Storing
Alloy for Power System Application
G S Grewal, V Shrinet and A K Singh
One of the most attractive methods of storing hydrogen which is rapidly emerging as the technique
with the highest degree of commercial promise, is the storage of hydrogen in a chemically bound
form as a solid state metallic hydride. In the present work, an effort has been directed for solving
the vexing problem of the poor activation characteristics of Magnesium, which typically requires a
large number of a-priori “dummy” sequential charging/discharging runs before it becomes possible
to react magnesium with hydrogen to its full theoretical capacity. This work has been undertaken in
a rigorous Taguchi methodology framework in which systematic combinatoric searches have been
made in the ternary magnesium-based alloy system MgxNi1–x–y My, with M being chosen from the
set comprising of Al, Cr, Fe and C and an alloy chemistry has been identified with high hydrogen
storage capacity along with rapid activation kinetics, which results in the near complete reaction
of the magnesium alloy in the initial few charging runs, only. The maximum absorption (formation
of hydride) has been measured as 7.4 wt% in about 60 minutes time. This value is about 97% of
the theoretical absorption capacity of magnesium.
Vol. 4, No. 1, March 2008
Linear Perturbation-based Simple and Rugged Load Flow
P Acharjee and S K Goswami
A reliable and robust load flow method has been developed based on linear perturbation technique.
The algorithm is simple. The decoupling properties between the power system quantities have
been exploited in developing the load flow algorithm. No complicated constraint satisfaction is
used, but simple mathematical computations are involved to develop the method. The proposed
load flow algorithm is rugged, can determine the maximum R/X ratios and the critical loading
conditions. The proposed method can find the solution when the conventional load flow method
fails. The efficiency and effectiveness of the algorithm has been established showing test results of
the different standard and ill-conditioned systems.
Coordinated Control of FACTS Controllers
N K Sharma, Arindam Ghosh and R K Varma
This paper discusses the issues of control coordination between SVC and TCSC for multi-machine
power system. The parameters of FACTS controllers are obtained using simple and effective root
loci technique and modal clamping technique. Subsequently the effects of system loading and
level of compensation on the controller parameters are investigated in depth. The results obtained
from various studies are further refined and validated through step response studies. The results are
presented for 9-bus WSCC test system.
10. Supplementary HVDC Controls for Multi-machine System Stability Improvement
V Sandeep Reddy, Dr P S Raju and P V Ramana Rao
This paper deals with the improvement of multi-machine power system stability using supplementary
HVDC controls. The current controller model and the line dynamics are considered in the stability
analysis. Initially, a combination of control signals required for the HVDC power modulation is
determined to improve the power system stability. A fuzzy logic controller is then proposed, which
utilises a set of control rules to vary the gains of the above controller and this has been found to
improve the system stability further.
Vol. 4, No. 2, September 2008
THE JOURNAL OF CPRI - Vol. 4, No. 2, September 2008
Emerging Applications of Polymers to Energy Sector
Dr J Sundara Rajan
This paper reviews many new and emerging areas of polymer science and its application to power
engineering. Electrical and electronic devices make extensive use of polymers in applications ranging
from connectors, sockets and switches to bushings, spacers, control panels, supports etc. New areas
like electro-active polymers and conductive polymers are finding many applications in everyday
use. Conductive polymers unlock the potential to improve a variety of items from electronics to
electrical engineering. Hydrogen fuel cells hold promise for the future. This paper highlights the
importance of developments in polymer science and its relevance to power engineering.
Multistress ageing of 28 kV Silicone Rubber Insulators under West and East Coast
conditions of the USA
Raji Sundararajan
Long term ageing of polymeric insulators was performed simulating coastal San Francisco and
Boston. 28 kV silicone rubber insulators were used for this purpose. The same insulator (design and
material) was compared at two different locations (West and East Coasts of the USA—San Francisco
and Boston). Weather cycles simulating coastal San Francisco and Boston were developed. The
various stresses applied include UV radiation, salt fog to simulate contamination from air-borne
particles, clear mist, rain, heat, cold and electrical stress. Data acquisition of the leakage current
and cumulative charge is also done by LabVIEW. High voltage divider was used to measure 20 kV
using LabVIEW at 2 V. They were aged for thousands of hours and their ageing and degradation
were characterised using physical (discolouration, chalking, cracking, hydrophobicity), electrical
(surface leakage current, cumulative charge and watts loss) and state-of-the-art material diagnostic
techniques such as FTIR, SEM and XPS. Results indicate that silicone rubber insulators withstood
these stresses well.
Nanostructured Superhydrophobic Coatings
M Farzaneh and D K Sarkar
A short description of the activities and facilities of the CIGELE/INGIVRE Chairs in relation with
superhydrophobic and icephobic nanometric coatings has been reported. A brief description of how
superhydrophobicity can help mitigate the ice accretion problem on power network equipment and
other exposed structures by reducing adhesion of ice to surface has been presented. Basic models
namely the Wenzel and Cassie-Baxter models accounting for the contact angle of water on solid
surfaces relating to the influence of surface roughness on hydrophobicity have been discussed.
The CIGELE/INGIVRE research team involved in the development of nanometric materials is
actively working on the elaboration of superhydrophobic aluminium surfaces by chemical etching,
superhydrophobic copper surfaces by silver nanoparticles, superhydrophobic nanostructured oxides
and superhydrophobic nanofibres. Some of the promising results achieved on superhydrophobicity
have been described.
Vol. 4, No. 2, September 2008
Effect of Biocontamination on Polymer Insulators
M N Dinesh, V Krishnan, N Vasudev, K N Ravi, P V Vasudevan Nambudri, K Suryanarayana
Problems due to biocontamination of insulators have been reported in tropical areas of the
USA, Sri Lanka, Tanzania, Germany, Sweden, Japan, Mexico, Paraguay and New Zealand. No
systematic study has been done to investigate the long term performance of polymeric insulators
with biocontamination. When fungi and other microorganisms colonise the surface of an insulator,
they impede the drying of the insulator surface and there is a possibility of increased insulator
degradation by enzymes secreted by fungal contaminants. Biocontamination causes concern among
utility engineers because it is not understood fully. In the present work, algae was allowed to form
on silicone rubber insulators. These insulators were then tested under salt fog conditions for a
period of 10000 hours and the results are presented.
Polymers as Core Materials in Power Engineering
K T Varughese
A brief overview on the growing impact of polymers, in their different forms, playing a critical role
in the power transmission and distribution is presented. The selection criteria of conventional and
specialty polymers as matrix material in power devices depends on their specific properties and the
ability to mix with property enhancing additives under passive or active states of electrical stress.
Recent advances on nanodielectrics are reviewed. The importance of polymers in switchgears,
overhead lines, power cables, transformers and substations are indicated.
Water Droplets on Polymeric Surfaces under the Influence of High Voltages
Michael G Danikas
In this paper, the problems arising from the application of uniform AC electric fields on water
droplets, which are on polymer surfaces, are investigated. Polymeric materials such as silicone
rubber, PVC and rubber were used. The flashover voltage was investigated in terms of water
conductivity, polymer surface roughness, droplet volume and droplet position w.r.t. the electrodes.
Our research showed that all four aforementioned parameters influence the flashover voltage.
Effect of Cross-linking Systems on the Thermal Behaviour of Nylon copolymer
(PA6,66) and Ethylene-Propylene-Diene (EPDM) Rubber Blends and their Kinetic
Cibi Komalan, K E George, S Thomas, K T Varughese
The thermal stability of nylon 6,66 and ethylene-propylene-diene rubber of dynamically vulcanised
blends were studied by thermogravimetric analysis. The composition of nylon copolymer and
EPDM was fixed at 70/30 ratio by weight. The blends were prepared by melt mixing in a Brabender
Plasticorder. Thermogravimetric analysis showed that the decomposition proceeds through a single
step even though the blends are immiscible and the cross-linked blends were more thermally stable
than uncross-linked blends. The kinetic parameter of the degradation process is also studied.
Vol. 4, No. 2, September 2008
Role of the Interface in Improving Surface Degradation Properties of Epoxy
Parimal Maity and Nandini Gupta
It is widely accepted that the interface between polymer and filler particles plays a major role
in modifying composite properties, both electrical and otherwise. In this work, we examine the
role of the interface in affecting a particular electrical characteristic of the nanocomposite, viz.
its resistance to surface degradation. Dielectric materials with improved resistance to surface
discharges would help in ensuring better performance and greater reliability of apparatus in service.
This paper takes a comprehensive look at the recent work by the authors in this area, and tries to
understand the role of the interface in this context. Two essential features emerge. Increase in the
interfacial zone at the expense of the bulk polymer imparts better degradation resistant properties
to the composite specimen and tailoring of the chemical bond structure at the interface leads to
further improvement.
Electroluminescence and Space Charge in Nanodielectrics subjected to AC Voltage
S S Bamji, M Abou-Dakka, A Bulinski and L Utracki
Electroluminescence (EL) and Phase Resolved Pulsed Electro-Acoustic (PRPEA) techniques are
used to determine charge injection and space charge distribution in insulation subjected to an AC
electric field. It is shown that both EL and PRPEA can provide information about the dynamics of
charge injection and trapping in solid dielectrics under an AC field. Such techniques are useful in
evaluating novel materials, such as nanodielectrics, for use in power apparatus.
10. Fire Safety Assessment of Polymeric Cables and Materials based on Heat Release
Rate, Combustion Smoke and Toxicity
B Nageshwar Rao, R Arunjothi, A R Srinivasan, P Rajashekhar and A Sudhindra
This paper presents and discusses heat release measurement, smoke and toxicity data obtained on
cables: power, communication, automobile, wires and other materials used for various applications
in power plants, petroleum refineries, metro rail, automobile industries. Fire survival cables
intended to maintain electrical integrity under flaming conditions and flame retardant low smoke
cables have been evaluated and their performance discussed. Fire safety assessment methods of
cables and materials are reviewed and heat release rate, smoke, toxicity data and flammability
characteristics obtained on materials like polystyrene, cellulosic fibre materials, upholstery, FRP/
GRP laminate and others are discussed. Cushioning materials like polyurethane foam (slab stack,
rigid PU, Expandable Graphite foam), thermally densified polyester block have been evaluated for
HRR, smoke properties and the results are discussed. The toxicity of these materials evaluated as
per NES 713/NCD 1409 are summarised.
Vol. 4, No. 2, September 2008
11. Electron Beam Cross-linking: An Emerging Technology for Processing Electrical
Wires, Cables and Accessories
V V Pattanshetti and J Sundara Rajan
Polymers are extensively used in various power engineering applications for its excellent dielectric
and mechanical characteristics. Electron beam technology lends further support for expanding the
application of polymers in power engineering. The use of electron beam cross-linking of polymers
in preference to the conventional chemical cross-linking processes has several advantages. This
paper discusses the advantages of this technology with particular reference to power cable and
accessories for termination and joints. The improvements in dielectric, mechanical and thermal
characteristics are emphasised to highlight the need for increasing the use of this technology for
critical power engineering applications.
Vol. 5, No. 1, March 2009
THE JOURNAL OF CPRI - Vol. 5, No. 1, March 2009
Techno Economic Viability of Hybrid solar (PV) - AC Utility Interfaced Power System
for Rural India
S. N. Singh and A .K. Singh
A hybrid solar photovoltaic(PV) - AC utility interfaced power generating system has been developed
for domestic use. The system consists of a photovoltaic array (installed on the structure of roof), an
intelligent power controller and an inverter with battery as an energy storage device. The system
works in such a way that it utilizes maximum power from PV source, convert it into useful AC
power for household critical loads. The variation in PV power is supplemented by grid power
source integrated with the PV source. The system finds wide application in rural sectors where the
conventional source of supply has been restricted and further expansion of utility (grid) supply is
not possible due to various technical & economic reasons. Thus it saves grid power and reduces the
over burdening of power on grid lines . The technology of solar energy conversion into useful AC
power through push-pull configured transistorised inverter involve PWM strategy which produces a
very near sine wave output with minimum THD, leading to a high efficient system. The system has
been designed for 300 W power supply for critical loads. The simulation for generation of PWM
pulses and computation of THD value has been carried out. Performance of the system was tested
under various abnormal conditions like grid failure, low or no sunshine conditions etc. The system
provides optimum use of solar PV power with environmental benefits.
End-of-Life Evaluation of RTV Coated Porcelain and Glass Insulators Under Pollution
Shaik Abdul Saleem, J. Amarnath, K. A. Aravind and D. Devendranath
Ageing of Room Temperature Vulcanizing (RTV) silicone rubber coated porcelain and glass
disc insulators are reported under combined voltage stress and salt-fog conditions till the loss of
hydrophobic properties of RTV coating in an aging chamber. The electrical characteristics are
obtained by on-line monitoring of leakage current and material characteristics are analyzed by
Energy Dispersive X-Ray (EDX) Analysis. RTV coated glass insulators shattered in to pieces after
2600 hours of aging while RTV coated porcelain after ageing for 4600 hours lost its hydrophobic
properties and started behaving like a normal un-coatedporcelain disc insulator.
Diagnosis of Inter Turn Fault in the Transformer Winding using Wavelet Based AI
R.Rajeswari, Lecturer and Dr.N.Kamaraj
In this paper, Wavelet based ANFIS for finding inter turn fault of transformer is proposed. The
detector uniquely responds to the winding inter turn fault with remarkably high sensitivity.
Discrimination of different percentage of winding affected by inter turn fault is provided via ANFIS
having an Eight dimensional input vector. This input vector is obtained from features extracted
from DWT of inter turn faulty current leaving the transformer phase winding. Training data for
ANFIS are generated via a simulation of transformer with inter turn fault using MATLAB. The
proposed algorithm using ANFIS is giving satisfied performance than ANN and GABPN with
selected statistical data of decomposed levels of faulty current.
Vol. 5, No. 1, March 2009
Novel Method of Network Reconfiguration for the Compensated Network
M. Damodar Reddy and V.C. Veera Reddy
This paper delineates a novel method of network reconfiguration for the compensated network.
A two-stage methodology is used to reduce the losses and to improve the voltage profile of the
balanced radial distribution networks. In the first stage, capacitors are placed optimally for the
reactive power compensation of the original network. Fuzzy approach is used to find the optimal
capacitor locations and Particle Swarm Optimization (PSO) method is used to find the sizes of
capacitors. In the second stage, an improved fuzzy multi-objective algorithm is used for the network
reconfiguration of the compensated network. The proposed method is tested on 33-bus and 69-bus
test systems and the results are presented.
Day-ahead electricity price forecasting in Victoria Electricity Market using Support
Vector Machine based Model
Sanjeev Kumar Aggarwal, L.M. Saini, and Ashwani Kumar
In this paper, support vector machine (SVM), a new machine learning technique, based model to
forecast price profile in a single settlement real time electricity market has been presented. The
proposed model has been trained and tested on data from Victoria Electricity Market (VEM) to
forecast the Regional Reference Price (RRP). The selection of input variables has been performed
using correlation analysis and in order to take advantage of the homogeneity of the time series, fortyeight separate SVMs have been used to predict next-day price profile, with each SVM forecasting
price for each trading interval. Forecasting performance of the proposed model has been compared
with (i) a heuristic technique, (ii) a naive technique, (iii) multiple linear regression (MLR) model,
and (iv) neural network (NN) model. Forecasting results show that SVM model possesses better
forecasting abilities than the other models and can be used by the participants to respond properly
as it predicts price before closing of window for submission of initial bids.
The structure and cure mechanism of 2,3-bis(benzimidazolyl) pyridine with an epoxy
resin system
P.V. Reddy, Sakuntala Samuelson, M.Nethaji and N.M. Nanje Gowda
2, 3-bis (benzimidazolyl) pyridine was synthesized and characterized by CHN analysis and
techniques like infrared spectra, mass spectra and NMR studies. The structure was established
using X-ray crystallography technique.
The cure behaviour of 2, 3- bis (benzimidazolyl) pyridine has been investigated with Bisphenol-A
based epoxy resin with an anhydride hardener. The study has revealed that this ligand behaves
like an accelerator by reducing the cure and gel times of the resin system. Kinetic studies based
on DSC showed that the rate of curing increases with enhanced concentration of this accelerator.
The electrical properties of the cured epoxy resin were unaffected with lower concentrations of
2,3 bis (benzimidazolyl) pyridine. A mechanism for curing has been proposed based on infrared
spectral studies which indicate the involvement of the secondary and tertiary nitrogen of 2,3
bis(benzimidazolyl)pyridine which enhances the cross-linking of the resin system.
Vol. 5, No. 1, March 2009
Optimum Cost of Generation for Maximum Loadability Limit of Power System using
Multiagent Based Particle Swarm Optimization (MAPSO)
A.Shunmugalatha and S.Mary Raja Slochanal
To estimate voltage stability, maximum loadability limit (MLL) is one approach. MLL is the margin
between the operating point of the system and the maximum loading point. The optimum cost
of generation for MLL of power system can be formulated as an optimization problem, which
consists of two steps namely computing MLL and the optimum cost of generation for MLL. This
paper utilizes the newly developed Evolutionary Multiagent Based Particle Swarm Optimization
(MAPSO) in solving this optimization problem. Details of the implementation of the proposed
method to modified IEEE-30 bus system, IEEE-57 bus system and IEEE-118 bus system are
presented. Simulation results show that the proposed approach converges to better solution much
faster, which prove the loadability and applicability of the proposed method.
Optimal Coordination of Directional Overcurrent Relays using Charalambous Least
pth Algorithm
N. A. Laway
In this paper, a new method for optimum coordination of directional overcurrent relays in
interconnected multi-loop power systems is proposed. The method is based on Charalambous Least
pth Algorithm. Normally the optimal directional overcurrent relay coordination problem is solved
by using Simplex Method of Linear Programming, which is a computationally intensive method.
Considerable computational effort can be saved by using the proposed method. The method has
been applied to solve the optimal coordination problem of IEEE 14-bus power system and IEEE
57-bus power system. Comparison of the Simplex Method and the Charalambous Method has been
carried out for the determination of optimal settings of the relays of the systems under study.
A Review on Electrical Treeing in Solid Dielectrics
Michael G. Danikas and George E. Vardakis
Electrical trees constitute a cause of breakdown in solid dielectrics. Electrical trees are related with
partial discharges (PD), enclosed defects, which in turn cannot be separated from faulty interfaces.
In this review, certain aspects related to electrical treeing, such as space charges, PD and enclosed
voids are investigated. Charges, related to the electrical treeing must be classified in two categories.
The charges that are redistributed continuously in the interior of the tree channels and charges that
are moving and being trapped in the solid dielectric. The first category of charges constitutes the
PD charges and the second category charges are referred to as the space charges.
Vol. 5, No. 1, March 2009
10. Mixed H2/H∞ Control of Continuous-time Singularly Perturbed System - State
feedback computations
S A Akbar and A K Singh
This study brings out the scheme for the design of mixed H2/H∞ based feedback controller for a
continuous-time singularly perturbed system using state feedback computations. The mixed H2/H∞
control law was derived using auxiliary cost minimization approach and the feedback controller
was formulated for a linear time invariant lower and higher order continuous-time singularly
perturbed systems by solving iteratively coupled Riccati equations. The H∞-controller based on
mixed sensitivity approach and the Linear Quadratic Gaussian (LQG) controller were derived for
the same system. The time responses for unit step input and robustness properties such as Gain and
Phase margin were studied by formulating mixed H2/H∞, H and LQG systems.
11. Fuzzy Logic Based Fault Type Identification in Radial LT Power Distribution Feeder
Ahalya C and Shivakumara Aradhya R.S.
Fault classification is necessary for rapid restoration of service to LT consumers after occurrence
of a fault. This paper presents step by step procedure for identification of ten different types of
faults commonly occurring in LT distribution system. Information on the distribution transformer
secondary current for different faults at different load buses is used to define the input fuzzy
variables. Fuzzy inference engine and centroid de-fuzzifier are used to relate the input to fuzzy rule
base and to obtain crisp output respectively.
12. Performance Analysis of Solar Flat Plate Collectors in Scaling Environment
U C Arunachala, M Siddhartha Bhatt and Dr L. K Sreepathy
Scale formation in risers of solar flat plate collec tors is evident in places where hard water is being
used. This affects both the component functioning as well as system performance. In this paper,
the influence of scale deposition on instantaneous efficiency, mass flow rate and heat transfer rates
are analysed by the Hottel-Whillier-Bliss (H-W-B) equation in both natural and forced circulation
systems. It is observed that variation of mass flow rate affects collector efficiency more than
variation of heat transfer rates.
Vol. 5, No. 2, September 2009
THE JOURNAL OF CPRI - Vol. 5, No. 2, September 2009
Assessment of Stator Winding Insulation by Spectroscopic and Thermo-Analytical
Tech n iq ues
Nageshwar Rao B, Sundara Rajan J and Ramachandra B
Over the past few decades, the progressive deterioration of high voltage machine insulation has
been assessed through non-destructive techniques like measurement of Insulation Resistance.
Polarization Index. Dissipation Factor, Loss Angle and Capacitance. Partial Discharge (PD)
measurements, mainly for trend analysis [1-4]. The stator winding insulation deteriorates under the
conditions of thermal, electrical, vibration and thermo-mechanical stresses during service. Aging
process is complicated and takes place under stresses simultaneously or sequentially. Thermal
aging is a chemical process leading to molecular decomposition and oxidation of organic materials
resulting in decrease adhesive strength ot epoxy to mica surface and also to delamination at the
interface between mica and epoxy [5,6], Delamination further aggravates under thermo-mechanical
force. Small cracks are likely to be generated in epoxy rich areas due to thermal aging which
could trigger electrical and chemical changes that insulation undergoes during aging is limited
and not fully explored and is of absolute necessity to understand the deterioration mechanisms.
This paper reviews the various spectroscopic and thermo-analytical techniques that are used for
characterization of materials and presents the laboratory investigations carried out to understand
the structural changes that stator winding insulation under goes during aging.
Study on Dynamic Characteristics of 3D Reinforced Concrete Frame with Masonry
Chethan. K, R. Ramesh Babu, Katta Venkataramanna and Akanshu Sharma
Comprehensive experimental and numerical studies are carried out on the dynamic characteristics of
3 dimensional (D) reinforced Concrete (RC) frame with Masonry Infill (MI). MI though considered
as non-structural element largely effect strength, stiffness and ductility of the framed structure
during the application of lateral loads such as wind and earthquake loads. This paper is a part of
collaborative research project between CPRI and BARC focusing on the influence of MI on the
natural frequencies of 3D RC frame and comparison of the results with the design codes. A 3D
RC frame having two bays and three storeys is designed and detailed as per the relevant Indian
standard codes. A simple numerical model is been formulated to obtain the natural frequencies in
the FE analysis and Tri-axial shake table of 3m x 3m is used for the experimentation. The details
of the numerical analysis and experiments carried out in the research work are brought out in this
Vol. 5, No. 2, September 2009
Optimization of Arc Erosion Resistance of Silver Tin Oxide Electrical Contacts
Prepared using the Electroless Route
S. S. Godkhindi, G. S. Grewal, P.B. Joshi, M. Ramamoorty, N.J. Buch
The use of cadmium and cadmium oxide containing contact materials has been strongly discouraged
in most parts of the world in view of the toxicity of these materials and resultant environmental &
health hazards. Tin oxide has emerged as a substitute material in place of cadmium oxide as the
major modern silver-metal oxide contact system for industrial application. The traditional methods
of synthesis of silver-cadmium oxide composite contacts (namely internal oxidation and powder
metallurgy route of co-precipitation) have been found to be unsuitable for production of silver-tin
oxide contact material mainly because of incompatibility of existing compounds of tin metal that
are water soluble and which can be used for co-precipitation with silver salt such as silver nitrate
as well as the very slow rates of internal oxidation of tin in silver-tin oxide system as compared to
that of cadmium in silver-cadmium oxide system. For synthesis of silver-tin oxide powders, a novel
method based on electroless coating, has been developed. In the present work, an optimization
study has been undertaken for improving the arc erosion characteristics of silver tin oxide contacts,
prepared using the novel electroless route with additions of a tertiary stabilizing tungsten oxide
dopant. The work have been undertaken in a Statistical Factorial Design of Experiment (SDOE)
setting using the one way ANOVA technique.
Design and Performance Evaluation of FRP cross arm For Transmission Line
Selvaraj.M, Kulkarni.S.M and Ramesh Babu.R
The technology of compaction of power transmission lines is being increasingly adopted by
power industry to effectively make use of the Right of Way (ROW). For technical, aesthetic and
economical reasons, our future transmission lines will have to be built with new design concepts
using new materials. An attempt was made to build the transmission line tower cross arm with
pultruded sections of Fibre Glass Reinforced Plastic (FRP) as a substitute for steel. The metallic
towers have been deteriorating and corroding as a result of being in hostile environment i.e.,
wind, rain and salty environment etc. This paper describes the mechanical behavior of FRP tower
cross arm assembly simulated using Finite Element Analysis ( FEA) software and compared with
experimental results.
A methodology for computation of experimental annual station heat rate bench
M.Siddhartha Bhatt, S.Seetharamu and N.Rajkumar
This paper presents a methodology for assessment of annual heat rate of a coal fired thermal power
unit based on a snap shot test to which various factors contributing to annual effects are added.
This method is successfully used a number of stations and represents the unit heat rate (UHR)
and station heat rate (SHR) fairly well. This method is not a substitute for measurement of heat
rate by direct measurement of coal flow and energy generated and is applicable only where direct
measurement of coal flow into an individual boiler by gravimetric feeders or belt weighers is not
available. This method is superior to other methods in view of its total coverage of all effects and
no annual factor which affects heat rate is left out. Hence it is popularly accepted by most thermal
stations. This method is superior to backward computation of UHR from SHR by apportioning.
Vol. 5, No. 2, September 2009
Effect of Abrasive types on the Three-body Abrasive Wear Behaviour of Glass-Vinyl
ester and Carbon-Vinyl ester Composites
B. Suresha, P. Sampathkumaran, S. Seetharamu and Kishore
Woven fabric reinforced polymer composites are attracting the attention of material scientists in
recent years in view of enhancement in physical and mechanical properties as well as ease in
processing. Though woven fabric type and lay out of composite is known to control the properties,
the information on the tribo-performance of the woven fabric reinforced vinyl ester composites in
the literature is scanty. Hence, the present investigation focuses on the vinyl ester based composite
reinforced with glass fibers in one case and carbon fibers in the other case. They were made
by vacuum assisted resin transfer moulding process. Further, the samples were characterized for
three-body abrasive wear behaviour using dry sand rubber wheel abrasion tester with two different
abrasives (silica sand and quartz). The wear data revealed that the C-V composite showed lower
abrasion loss compared to G-V composite. The scanning electron microscopic pictures depicting
the worn surface features supported the wear data.
Corrective Control Strategies for Mitigation of Line Overloads during Con tangencies
Manoj Kumar Maharana and K. Shanti Swarup
This paper presents a new corrective control strategy to.mUigate the transmission line overloading,
with the help of a local optimization concept. A new Direct Acyclic Graph (DAG) technique for
selection of participating generators and buses with respect to a contingency is presented. Particle
Swarm Optimization (PSO) technique has been employed for generator rescheduling and/or load
shedding problem locally, to restore the system from abnormal to normal operating state. The
effectiveness of the proposed approach is demonstrated for different contingency cases in IEEE 14
and 30 bus systems. The result shows that the proposed approach is computationally fast, reliable
and efficient, in restoring the system to normal state. After a contingency with minimal control
Remuneration towards Frequency Regulation Service Provision in India through A
Novel Capacity Linked Mechanism
S. K. Parida, S. N. Singh ,S. C. Srivastava ,and P. Chanda
In India, the frequency regulation service has been provided by the generators ,operating under
Free Governor Mode of Operation (FGMO), with certain regulatory basis prescribed by Central
Electricity Regulatory Commission (CERC) in Indian Electricity Grid Code (IEGC). No incentive
is Being provided towards the capacity reserved for frequency regulation service. In this paper, -a
capacity linked mechanism has been proposed in order to encourage the participants to provide
regulation service. Index Terms - Unscheduled interchange mechanism, Frequency regulation
service, Free governor mode of operation.
Vol. 5, No. 2, September 2009
Optimal Allocation of Distributed Generators in a Competitive Electricity Market
N. Kumar, B.K. Keshavan, R.Nagaraja
This paper presents a sensitivity based technique for assisting network planners to determine the
optimal location and capacity of distributed generators (DG) in a capacity and location constrained
distribution network with the objective of minimization of losses in a competitive electricity
The liberalization of electricity markets has changed the way power generation technologies
are valued. The issues that need to be considered in the choice of rating and positioning of DG
include both technical and commercial factors. The proposed methodology takes this aspect into
consideration and only from among the practicable sites specified by the Distribution system planner
both optimal locations and capacity of DGs are determined.
It has been applied to a test system of nine bus radial distribution network considered as capacity
and location constrained for implementing DG. The technique is efficient and very much useful as
it can be directly applied to any distribution network having practical constraints for implementing
To show the effectiveness of this technique it was applied to IEEE 6-bus system without any
location or capacity constraint and the result was compared with test results of other methods. It is
interesting to note that over a wide range of DG penetration the proposed methodology results in
largest reduction in loss per unit DG penetration.
10. Ambiguity on the definition of Power Quantities in Electrical System
Sujatha Subhash and R K Hegde
This paper aims at presenting a review the definitions of power quantities in an electric system with
distorted voltages and currents. This subject has been of interest for more than a century and over
the years many definitions for reactive power and apparent power and compensation techniques
have been developed. However none of these definitions characterize the distinguishing power
quantities for all conditions of electrical circuit. A review of the ambiguities, confusion in the
classical definition, power theories and difficulties in instrumentation, billing and compensation is
presented in this paper.
Vol. 6, No. 1, March 2010
THE JOURNAL OF CPRI - Vol. 6, No. 1, March 2010
Influence of Spin Softening on Natural Frequencies of A Steam Turbine Rotor Assembly
with Interference-fit
B.Gurudatt, S.Seetharamu, P.Sampathkumaran and Vikram Krishna
Vibration is the default state of all mechanical systems that causes them to possess a natural
frequency. The significance of natural frequency cannot be emphasized enough, considering the
fact that its study is essential in averting resonance which causes violent swaying motions and
catastrophic failures in improperly constructed structures. In case of rotating structures, the study
of natural frequency is incomplete without the understanding of spin softening. This paper presents
an ANSYS based analysis to study natural frequency variation due to spin softening, but in a
faster and more accurate way than conventional GUI-based ANSYS analysis. The conventional
GUI based ANSYS procedure is a laborious time consuming process, what with the user having to
perform multiple iterations of modal analysis involving different rotational velocities to examine
the variation of natural frequencies of the system. Through this paper, a novel way has been
suggested to bring down the time and effort involved in such a study by using an advanced ANSYS
feature called ANSYS Parametric Design Language(APDL). The results obtained have been found
to validate spin softening.
Power System Stabilization by a Coordinated Application of Power System Stabilizers
using Hierarchical Neuro-Fuzzy Logic,
N. Albert Singh, K. A. Muralidharan and K Gomathy
Power system stabilizers (PSS) are used to generate supplementary control signals for the excitation
system in order to damp the low frequency power system oscillations. To overcome the drawbacks of
conventional PSS (CPSS), numerous techniques have been proposed in the literature. Based on the
analysis of existing techniques, this paper presents the stabilization of multi-machine power system
based on coordinated Adaptive Hierarchical Neuro-Fuzzy network based power system stabilizer
(AHNFPSS) design. The proposed system consists of a Hierarchical neuro fuzzy controller, which
is used to generate a supplementary control signal to the excitation system. The proposed method
has the features of a simple structure, adaptivity and fast response. The proposed controller is
evaluated on a multi-machine power system under different operating conditions and disturbances
to demonstrate its effectiveness and robustness. Eigenvalue analysis shows that the undamped
modes are sensitive to excitation control while speed governors have little influence on damping.
Vol. 6, No. 1, March 2010
Application of Fuzzy logic and particle swarm optimization for reactive power
compensation of radial distribution systems,
S. M. Kannan and Others
The main objective of this work is to study optimal location and size of the capacitor to be placed
in radial distribution feeders to improve the voltage profile and to reduce the energy loss. The
problem formulation considers three distinct methods related to maximize the savings function and
capacitors to be installed, as well as increasing the voltage profile. This paper uses fuzzy expert
system for capacitor location, practical mathematical procedure and particle swarm optimization
method for sizing. Initially, the load flow solution for the radial feeder os obtained by Newton
Raphson algorithm. Voltage, power factor and real power loss index of distribution system nodes
are modeled by fuzzy membership function. Then, a fuzzy inference system containing a set of
heuristic rules is designed to determine candidate nodes suitable for capacitor placement in the
distribution system. Capacitors are placed on the nodes with highest sensitivity index. The sizing
is found by using both practical mathematical procedure and particle swarm optimization. Each
method differs from others in terms of fuzzy expert system inputs and sizing methods. The intent
of this paper is to study and discuss the results of these methods with reference to savings cost. The
proposed methods are tested in 11kV, 12 bus IEEE test radial feeder system and results simulated
from MATLAB.
Impact of DG placement and sizing on distribution system
Tanmoy Malakar and Nidul Sinha
Distributed Generation (DG) technology has emerged as a key important issue in distribution
system planning, reliability and optimization for quite sometimes now. Apart from economic power
generation and its efficient transfer, major interests have been observed to plan the distribution
system with the presence of small energy sources. This paper addresses a novel technique for
optimal placement and sizing of DG into electric power distribution systems. Emphasis has been
made to find the impact on voltage profile and power loss of the distribution network with different
DG locations and sizes subject to satisfaction of network security constraints. A power flow based
simple mathematical formulation has been made. Programs were developed in Matlab for solving the
problem. Results reveal that while finding the optimal location and sizing of a DG in a distribution
system, both power loss and network security aspects of the network must be considered in addition
to minimum voltage deviation as they influence the optimal results significantly.
Vol. 6, No. 1, March 2010
Optimum Coordination of Overcurrent Relays Using Revised Simplex Method
Prashant P Bedekar and Others
The Over Ccurrent relays (OCRs) are the major protection devices in a distribution system. To
reduce the power outages, mal-operation of the backup relays should be avoided, and therefore,
OCR time coordination in power distribution network is a major concern of protection engineer.
The OCR time coordination in ring fed distribution networks is a highly constrained optimization
problem. The purpose is to find an optimum relay setting to minimize the time of operation of
relays and at the same time, to avoid the mal-operation of relays. The problem can be stated as a
linear programming problem (LPP). This paper presents revised simplex method for optimum time
coordination of OCRs in ring fed distribution systems. The LPP of OCR coordination involves
large number of variables and constraints. As the revised simplex method works with the reduced
table, the amount of computations and the memory requirement is very much reduced. Thus the
calculations to be performed reduce to a great extent. Comparison with dual simplex, Big-M simplex
and two phase simplex method is also presented.
Availability simulation modeling and performance optimization of the screening unit
in a paper plant
Rajiv Khanduja, P.C. Tewari, R.S. Chauhan
This paper deals with the availability simulation modeling and performance optimization of the
screening unit in a paper plant. The screening unit of a paper industry has four main subsystems,
arranged in series and parallel configurations. Considering exponential distribution for the probable
failures and repairs, the mathematical formulation of the problem is done using probabilistic
approach and differential equations are developed on the basis of Markov birth death process.
These equations are then solved using normalizing conditions so as to determine the steady state
availability of the screening unit. The performance of each subsystem of the screening unit in a
paper plant has also been optimized using genetic algorithm. So, the findings of the present paper
will be highly useful to the plant management for the timely execution of proper maintenance
decisions and hence to enhance the system performance.
Dual Mode Linguistic Hedge Fuzzy Logic Contoller for an Isolated Biomass Based
Diesel Wind Hybrid Power System with Battery Energy Storage Unit
S. Velusami and M. Md. Thameem Ansari
In this paper, a dual mode linguistic hedge fuzzy logic controller for an isolated biomass based
diesel-wind hybrid power system with battery energy storage unit is proposed. In this fuzzy
logic controller design, the linguistic hedge operators are used to adjust the shape of the system
membership functions dynamically, and can speed up the control result to fit the system demand. The
genetic algorithm-simulated annealing algorithms are adopted to search the optimal linguistic hedge
combination in the linguistic hedge module. Dual mode concept is also incorporated in this proposed
controller because it can improve the system performance. The system with the proposed controller
was simulated and the frequency deviation resulting from a step load disturbance is presented. The
simulation results shows that the system performance is improved with the proposed controller. It
is also found that the controller is less sensitive to the changes in the system parameters.
Vol. 6, No. 1, March 2010
Sesment of Stator Winding Insulation Part 1 - Review of Condition Monitoring
Nageshwar Rao B, Mallikarjunappa K, Sundara Rajan J, Ramachandra B and Sudhindra A
This paper reviews the main aging and failure mechanisms of stator windings, as well as the options
associated with each mechanism for extending the useful life of the machine. The symptoms for
each failure mechanism are discussed. An overview of various electrical diagnostic techniques for
condition assessment of stator winding insulation. is summarized.
Assessment of Stator Winding Insulation Part 2 - Tests on Inservice Machines
Nageshwar Rao B, Mallikarjunappa K, Keri C.D, Afzal Ahamed, Sudhindra A
and Ramachandra B
This paper presents the test results and analysis made on several machines at site. Case studies are
employed to illustrate the usefulness of measurements on the stator windings in service.
10. Determining optimum Time Multiplier Setting and Plug Setting for Overcurrent
Relays using Continuous Genetic Algorithm
Prashant P. Bedekar,Sudhir R. Bhide and Vijay S. Kale
Overcurrent relays (OCRs) are the major protection devices in a power distribution system. To
reduce the power outages, mal-operation of the backup relays should be avoided, and therefore,
OCR coordination in power distribution network is of great importance. The time of operation
of OCRs can be reduced, and at the same time the coordination can be maintained, by selecting
the optimum values of time multiplier setting (TMS) of OCRs. Instead of keeping the value of
plug setting (PS) as fixed (while determining the optimum value of TMS), it is also possible to
select the optimum values of both TMS and PS, which can further reduce the time of operation
of OCRs. The main contributions of this paper are - 1) systematic method for formulation of
problem of determining optimum values of TMS and PS of OCRs in power distribution network
as a constrained nonlinear optimization problem, 2) converting the problem into an unconstrained
optimization problem, making use of the penalty method, and 3) applying continuous genetic
algorithm (CGA) technique to get the optimum solution of this problem.
Vol. 6, No. 1, March 2010
11. Comparison of tracing based real power transmission loss allocation methods in
deregulated power system
S. Arunachalam, D. Ramya and P.K. Nithyha
This paper compares the transmission loss allocation procedures through tracing using proportional
sharing rule and provides a detailed comparison of three alternative methods: 1) Graph based tracing
2) Matrix based tracing and 3) complex power flow tracing. The methods are based on tracing the
real and reactive power flow through the network and determining the share of each load on the
flow and losses through each line. Power flows of generators and loads are traced to determine the
transmission system usage by each generator and load. Then transmission losses caused by each
generator or load are determined. Unbundling, (electric energy can be separated commercially as a
product from transmission as a service) an idea, which the current deregulation market hinges on
is carried out and considers the coupling between active and reactive power flows as well as the
cross effects of active and reactive power on active and reactive losses. Tracing algorithms which
can be considered direct to a good extent are implemented for these three methods. A case study
based on a four buss system is provided and results obtained using MATLAB code is presented
Vol. 6, No. 2, September 2010
THE JOURNAL OF CPRI - Vol. 6, No. 2, September 2010
Investigation of Insulation Performance of High Voltage Rotating Machines using
Intelligent Techniques
K.Sathiyasekar, K.Thyagarajah&A.Krishnan
The condition of insulation performance of a high voltage rotating machine has been analyzed
using Back Propagation Neural Network (BPN), Fuzzy logic and BPN network with Proportional
Integral and Derivative (PID) controller concept along with slope parameter. The economic aspects
of its periodic maintenance, the loss in production due to breakdown, the investment cost due to
frequent replacement with a new machine is huge. The insulation condition of the machine can
be assessed by measuring the various parameters like capacitance, leakage current, dissipation
factor, polarization index, surge voltage withstanding strength and partial discharge magnitude.
To assess these parameters of the insulations used in high voltage rotating machines, a number of
measurements have been made on actual stator coils of machines. For various test voltages, the
capacitance, leakage current and dissipation factor are measured and correlated as a function of test
voltages. It is observed from the simulation results that BPN with PID techniques gives accurate
results, predicting the performance of stator winding insulation.
A Low Cost Digitally ControlledBrushless DC Motor Drive Designing
V. M. Takodia, J. J. Patel & M. A. Mulla
This paper presents a low cost, digitally controlled, closed loop BLDC motor drive. Normally
encoder feedback is required to get a speed feedback between two hall sensor status changes, for
robust controller designing. With a view to reduce the cost, in this design an encoder feedback is
avoided and moving average speed estimation with variable Kp-Ki PI controller is realised. The
digital controller Cortex M3 ARM microcontroller LM3S2616 is implemented with only hallsensors feedback and variable Kp-Ki PI controller algorithm. The experimental setup is verified by
loading motor from no load to full load as well as with continuous and impact load. Serially, motor
parameters like speed, current are gathered on PC and analysed, they confirmed the simulated
Development of Small Signal Analysis Package using FACTS Devices for Dynamic
Stability Enhancement in Multimachine Power Systems
J.Gokula Krishnan &N.Senthil Kumar
This paper presents a systematic method of developing the mathematical model for small signal
stability analysis of power system using different types of FACTS device namely (i) SVC (ii)
STATCOM (iii) TCSC (iv) SSSC and (v) UPFC. In this paper, the two axis model of the synchronous
machine is used for investigating the small signal dynamic behavior of the multimachine power
system. Local stabilizing signals such as real power perturbations, bus voltage deviations are used
as control inputs for the damping controllers in FACTS devices. A nonlinear optimization model
is developed which tunes the gains, time constants of the FACTS based damping controllers in the
stabilizing loop. Case studies are carried out on the standard WSCC 3 Machine 9 – Bus system and
the 10 Machine, 39 bus New England system. All computations are carried out using MATLAB
Vol. 6, No. 2, September 2010
Digital Real Time Simulator for Testing of Load Shedding Controllers
Meera K.S., J.Sreedevi and R.S. ShivakumaraAradhya
Load shedding is one the main actions that can be used to prevent complete black out in industrial
plants during grid disturbances. In case of grid disturbances it is essential to isolate the industrial
plant units from the grid as quickly as possible to save the system. In importing mode of operation,
it is essential that after grid isolation the generators pick up additional power to meet the plant
loads. If adequate generation is not available, loads have to be shed to achieve load-generation
The load shedding schemes are designed based on various factors such as - power import before
isolation., excess margin available in inplant generators to pick up further load, response time
of governors to changeover from constant power mode to isochronous mode, rate of change of
frequency and actual frequency at the time of isolation etc. Thus, such schemes are to be tested
under realistic power system conditions including the protections used for islanding the system
from Grid. Testing of load shedding schemes requires the use of advanced testing tools to ensure
both protection functions and control logic to be tested using dynamic simulations.
In this paper, use of Real Time Digital Simulator (RTDS) at Central Power Research Institute,
Bangalore for testing of intelligent load shedding controllers is discussed. It is shown that
these controllers can be pre-commissioned and tuned, while connected to the simulator in a closed
A Novel Implementation Of PspiceModeling ForReliability Analysis Of Distribution
G.N.Sreenivas, P.Srividyadevi, M. DeeptiLavanya andV.Sankar
In this paper, Markov processes for determining the reliability indices of distribution system are
discussed. The continuous Markov modeling is applied to a complex radial distribution system
and electrical equivalent circuits are developed for the modeling. In general PSPICE is being
used for electrical and electronic circuits and various applications of power system like fault
analysis, transient analysis etc. In this paper, the SPICE modeling equivalent circuits which are
developed are applied in a novel way to Distribution System reliability analysis. These circuits
are simulated using PSPICE software to obtain the state probabilities, the basic and performance
indices. Thus the basic indices and the performance indices obtained by this method are compared
with those obtained by FMEA technique. The application of the concepts presented in this paper
are illustrated and analyzed for the IEEE -Roy Billinton Test System (RBTS)
Vol. 6, No. 2, September 2010
Minimizing monsoon load dips in coal fired thermal power plants
M.Siddhartha Bhatt andN.Rajkumar
Thermal power plants operating on low grade high ash coals experience capacity and performance
drops during the rainy season. The parameters like plant load factor (PLF), specific oil consumption
(SOC), auxiliary power (AP), station load are affected. There are two types of effect: effect of heavy
incessant rains for a period of 1-3 days which result in capacity dips and continuous decrease in
parameters over the 2-3 months monsoon season caused by decreased handling capacity and flow
of coal. The effect of monsoons is quantified in terms of deviation in the operating parameters by a
study of several stations over a wide geographical range. Typically for a 1 to 3 GW station for short
duration (1-3 days) peak load dips of the order of 25-35 %, SOC increase to 25-30 ml/kWh and AP
increase by 2-3 % of gross generation are experienced during heavy rainy periods. Instantaneous
load dips (2 h duration) can be much higher. For the monsoon season the dips in monthly PLF can
be 30-35 %, SOC can be 6-12 ml/kWh, auxiliary power increase is 1.5-3.0 % of gross generation
and forced outage % can increase to 4-5 times of the non-monsoon values.
The stations need to gear up to the demands of the rainy season through several preventive and control
measures. A monsoon management plan needs to be in place for handling O & M in this period on
the fuel front as well as on the boiler front. Well planned monsoon management can reduce severity
of the power dips to less than 15 % of the peak load.
Energy efficiency improvement in coal fired thermal power plants through optimization
of starts
M.Siddhartha Bhatt, Rajashekar P. MandiandN.Rajkumar
This paper presents a review the impact of transient operations in coal fired thermal power plants
on the unit heat rate (UHR). Once a tripping occurs, fuel oil, auxiliary electric power, steam and
coal is consumed to restore the unit back to its original plant level. From boiler light up to almost
20 % load, there is virtually no net generation from the unit. From 20 % load to 80 % load, the
energy efficiency is quite poor and uneconomical because of high auxiliary power and fuel oil
support. The annual impact of transient operations is almost 40-50 kcal/kWh in many stations and
this can be brought down to nearly 20 kcal/kWh by reducing the number of trippings as well as
the resource consumption during these operations. The outage period also need to be brought down
from nearly 60-80 hours/outage down to 30-40 hours/outage
Least Cost Integration Of Solar Energy Technologies Into Fossil Power Plants
M.Siddhartha Bhatt
This paper presents the optimal integration of solar energy into coal fired power plants. The solar
thermal energy can be integrated through augmentation of heating of make up water in the turbine
cycle without any other additional equipment and without interfering with the primary process.
Solar photovoltaic (PV) power can be integrated through supplementing the DC emergency loads
by charging the battery systems in the power plant. For a 250 MW coal fired plant, a solar flat
plate collector area of ≈ 8,000 m2 would reduce heat rate by 0.26 %. A PV capacity of 2 MW would
be able to provide a continuous capacity of 440 kW to meet the DC loads in normal course and
emergency requirements (1 h of autonomy). The capital cost for solar thermal collectors would be
around Rs. 7.9 crores and for solar PV it is around Rs. 16 crores. The payback period is around
4.6 years for solar thermal and 10 years for solar PV systems.
Vol. 6, No. 2, September 2010
Effect of Thermal Spraying & Plasma Nitriding Treatments on Fatigue Life of En-24
Shafting Steel
U. N. Puntambekar, G. S. Grewal, P. B. Joshi, P. Sampathkumaran and T. P. Govindan
In the present work, the fatigue strength modification factors for a number of surface engineering
treatments on EN-24 shafting alloy steels have been investigated. The surface treatments include,
thermal spraying with Alumina & Zirconia & Plasma nitriding with & without white layer. For
this purpose, Basquintype relationships for alternating stress versus cycles to failure have been
developed. Based on these relationships, the surface treatment modification factors in terms of
power law relationships have been evolved.
10. Robust Three Phase Silicon Carbide Heaters Controller Designing
M. D. Raval, V. M. Takodia, J. J. Patel and M. A. Mulla
Silicon Carbide (SiC) is non-metallic high temperature heating element which is widely used in
electric furnace and electric heating devices, but SiC heating elements are very sensitive to thermal
shock and offer negative temperature co-efficient of resistance which deteriorate its performances.
This paper gives the novel solution of these problems, and discusses a complete design of an
electronic heater controller to feed the three-phase SiC elements. The controller enables soft
starting, superior dynamic performance, reduce power losses, improves overall efficiency and
high reliability with basic variable AC voltage control capability. A 36 kW three-phase SiC heater
controller is designed, developed and tested, which confirms the theoretical and simulated results.
11. Seismic Qualification Of Transformer Bushing
Srujana Nandam, Indrani Gogoi, R.Panneer Selvam and Ramesh Babu
In the past, Electric Power Substation equipment showed unreliable post-Earthquake performance.
The catastrophic failures of circuit breakers, transformer-bushings and disconnect switches at the
substations are major causes of outages during past earthquakes. The satisfactory performance
of Transformer Bushing system during earthquake is very critical to ensure uninterrupted power
supply for effective rescue operations. Many transformers damaged during earthquake were already
undergone seismic qualification in the laboratory under real time design Earthquake motion.
Experimental test procedures recommended by the relevant Standards are being revised to remove
the discrepancies identified. A case study on seismic qualification of transformer bushing by Shake
table testing is presented in this paper.
Vol. 7, No. 1, March 2011
THE JOURNAL OF CPRI - Vol. 7, No. 1, March 2011
Experimental Investigations to Aid Interpretation of Frequency Response Analysis
Measurements for Diagnosing Transformers
M. Prameela, G. Radhakrishna Murthy and Pradeep M. Nirgude
Frequency Response Analysis (FRA) is an emerging diagnostic tool to assess the mechanical
integrity of the transformer. Proper guidelines on using FRA data for declaring the integrity of
transformer windings or indicating the extent of displacement/deformations are not yet available.
Interpretations of the Sweep Frequency Response Analysis (SFRA) data for diagnosing the
condition of the transformer windings are not yet clear. Experimental investigations were carried
out on a model transformer to obtain SFRA data for various simulated conditions like axial and
radial displacements, winding displacements and deformation, core faults etc for different test
configurations. The paper presents the results of these investigations and analyse them to form
the guidelines in interpreting the SFRA data for various test conditions to detect various type of
faults. It is observed from the analysis of results that, SFRA with different test configurations need
to be applied to detect the type of fault and faulty phase winding. The information presented in
the paper, from the simulated faults on transformers with SFRA measurements, will be useful in
the interpretation of FRA results to assess and diagnose the condition of transformer windings and
Simulated Annealing Based Optimal Solution Methodology under Deregulation Power
System Environment
Lokanatha Dhall Samanta, Jitendra Kumar Das and Bibhu Prasad Panigrahi
In economic load dispatch solution procedure, the fuel cost characteristics of a thermal generator is
usually approximated by (i) a quadratic function (ii) piecewise quadratic function, (iii) a polynomial
function with order higher than two. When functions in (ii) and (iii) are adopted the economic load
dispatch problem may have several optimum solutions with one being the global optimum solution.
To find the global or near global optimum solution, the new algorithm based on Genetic Algorithm
(GA) or Simulated Annealing (SA) etc., for solving the economic dispatch problem are needed.
In this paper the generation dispatch methodologies under deregulation power system environment
have been developed. The classical economic dispatch algorithm relies on the convexity of cost
function. However, in deregulated power market, the market strategies make the sellers’ bidden
cost function concave causing classical economic algorithm inapplicable. Here a special type of
algorithm is developed based on deregulation strategy and also a heuristic algorithm is proposed
which combines with the powerful searching mechanism of simulated annealing with mathematical
foundation on global optimization.
Vol. 7, No. 1, March 2011
Challenges and Developments in Numerical DistanceProtection
Venkatesh C. and K. Shanti Swarup
This paper discusses some of the major issues in third generation numerical distance protections
which are being faced by utilities and the solutions made available for these issues by relay
manufacturers. Each discussion are accompanied with simulation results obtained using matlab
and simulink. In addition to this some of the key issues which still need further research are also
Suppression of High Frequency Disturbances in Low Voltage Circuits Caused by
Vacuum Circuit Breaker Operation in Medium Voltage Indoor Substation
Chetankumar V. Patel, Varsha A. Shah and Khirad Dhabhar
In a high or medium voltage substation, the operation of circuit breakers can induce high frequency
over voltages in low voltage circuits known as an electromagnetic interference (EMI). The radiated
and/or conducted EMI can be the cause of damage or malfunction of low voltage electronic
equipment. This paper is focused on the effects of electromagnetic interference (EMI) produced due
to switching of medium vacuum circuit breakers (MV CB) on the functioning of Numerical relays
and measuring devices which are in the vicinity of 6.6kVVacuum circuit breaker and remedy for
reduction of effects of EMI. In this paper a unique and cost effective solution has been suggested
and implemented to bring down the EMI effects by installation of ferrite core on control cable bunch
and effective galvanized iron(GI) sheet shielding between source (MV CB) and victim(numerical
relay & meter).
Failure of Short Circuit Generators - A Case Study by CPRI Bhopal
Arun Kumar Datta, M. A. Ansari,N. R. Mondal and B. V. Raghavaiah
Switchgear Testing & Development Station prevalently known as STDS was established in 1965
at Bhopal by government of India as one of the unit of Central Power Research Institute. The
predominant objective of setting up this institute was to cater the short circuit testing needs of
various LT/HT power equipments in switchgear, controlgear and transformer field. Over the years
the unit has expanded and received all the national/international accreditations, further became
the member of Short Circuit Testing Liaison (STL). Today CPRI’s short circuit laboratories of
generator based and direct on line based are one of the leading laboratories in south east Asia.
Year 2006-07 was a test time for CPRI, Bhopal when both the short circuit generators have developed
technical snag, resulting in interruption of short circuit testing. It was a challenge for CPRI as well
as for the service provider to take repair work as so many technical intricacies were involved
including the reverse engineering process. Nation realized the importance of CPRI during the
shutdown period. This paper discusses about the occurrence of failure, its detailed diagnosis, root
cause analysis and the action taken thereafter. Short circuit generator is different from conventional
one in many aspects. Repairing experiences of these generators, along with the re-commissioning
process are also shared herewith.
Vol. 7, No. 1, March 2011
Literature Review on Frequency Regulation in Traditional Power Systems Restructured
Systems and Smart Grid
Devika Jay and K.S.Swarup
A literature survey on the main control strategies used for load frequency control in electrical
power systems is presented. This includes traditional as well as restructured power systems. As
load becomes more and more unpredictable and also as supply becomes distributed the frequency
control strategies for the emerging Smart grid must include demand-side management also. A
survey on demand response and Active load control is also discussed.
Establishment of Baseline data in Power Distribution of Electric Utilities in Karnataka
under R-APDRP
P.ChandhraSekhar, C.P.Jairam, T.Raghunatha, R.Sudhir Kumar, K.Devendra Rao,
VijiBharathi and Kiran. V. Madhugiri
This paper presents the field experience of authors during the establishment of base line data for
designated Project Areas under R-APDRP Programme .This paper also brought out sample base
line parameters estimation. It also emphasizes problems in the field during collecting data and
attempt to overcome the problems. The paper also emphasizes findings on ESCOM by focusing
project Area and Aggregate Technical and Commercial loss (AT&C).
Battery separator grade PVC resin for possible insulation applications
An emulsion grade resin has been checked for the purpose of battery grade separator properties
along with suspension grade PVC resin for insulation purpose. The study suggest that when
battery separator resin CP172 SG added to K6701, the elongation property decreases with increase
in its content i.e, the material attains rigidity suggesting that CP172SG is not a good absorbent of
plasticizer. It has been confirmed that the particle sizes of these 2 resins are not the same and a
just physical mixing need not be a homogeneous mixture and this could affect the properties of
the compounded material intended to use for HT cable. The samples CP 172 SG and K6701 both
may be used for LT PVC cable sheathing and CP 172 SG cannot be used in XLPE (cross linked
polyethylene) LT cables. However, only sample K 6701 can be used for insulation.
Technology development of Flame Retardant Low smoke material for wire and cables
for sheathing applications
An Attempt was made toDevelop technology for Low Smoke Flame Retardant Cable and Compound
with elimination of toxic chemicals in the formulation. The Extrusion trials using twin screw extruder
and cable coating with single screw extruder was successful. The results of the evaluation of the
cable and compound suggest that the composition seems to be satisfactory. However, large scale
production could not be taken due to the actual techno-economic viability of the commercialization.
This study paved the way for DSIR sponsored project for commercial exploitation under PATSER
Vol. 7, No. 1, March 2011
10. Enhancing Energy Efficiency of Auxiliary Power in a Coal Fired Thermal Power
Rajashekar P. Mandi and Udaykumar R.Yaragatti
This paper describes the auxiliary power consumption in Indian coal fired thermal power plants.
The factors influencing the auxiliary power are discussed in details. Increase in auxiliary power
due to lower plant load factor and causes for lower PLF are enumerated. The effect of poor coal
quality and their effect on auxiliary power are discussed. The effect of operational optimization,
adoption of new energy efficient technologies, design deficiencies, etc., are discussed in details
along with remedial measures to reduce the auxiliary power. The energy conservation measures
reduce the auxiliary power of 210 MW power plant from 11.59 % to 8.50 % with a payback period
of 1 to 5 years.
11. Load flow study of a radial distribution network
TejasVyas and Ranjit Roy
The paper presents the simple method for finding the load flow solution of a radial distribution
networkusing the Kirchoff’s current and Kirchoff’s voltage law. The method is tested on four
test cases: 16-node, 33-node, 69-node and 117-node network. Comparing to the existing methods,
the memory space requirement is very small and time required for the CPU execution is also
lower. Result shows that the proposed method is very efficient and competitive with the existing
12. Premature Failure and Remedial measure for Prototype Testing of UHV Transmission
Line Towers: an Overview
J. C. Mohanta and D. Revanna
The need for adopting bulk power transmission system with all possible ways to make support
structures economical and also to reduce the right of way (ROW) requirements has arisen in view
of accelerated growth of electrical network. This bulk power transmission has become compelling
due to separation of power sources to the areas requiring the power are at longer ranges, namely
inter- state & inter regional. In this direction, 400kV D/C & M/C system with quadruple conductor
configuration, 800kV/1200kV AC system & ± 500 kV/800 kV HVDC systems are now adopted
in India. Recently, CPRI has successfully tested the self-supporting type of 765 kV and 800 kV
AC and HVDC towers for POWERGRID. The prototype testing and the premature failure of these
towers in particular and some of special towers in general are described in this paper.
Vol. 7, No. 2, September 2011
THE JOURNAL OF CPRI - Vol. 7, No. 2, September 2011
Parameters Affecting The Performance Of Transformers Under Short Circuit – A
CPRI Experience
YugalAgrawal, M. K. Wadhwani and B. V. Raghavaiah
Transformers are basic electrical machines and they form a very vital link in any electrical power
transmission networks. During its service life, a transformer may experience number of short circuits
in the system in addition to the abnormal overloading and switching impulses. Such abnormal
conditions can cause the movement of the windings and failure of the supporting structures due
to electro – mechanical forces and may result in total failure due to inadequacy in design and
defective manufacturing process. Further, the rapid growth of fault level in the system network is
major a concern for short circuit withstand capability of a transformer in service for a long period
of time. With advanced modern technology and available short circuit test facilities, transformer
manufacturing industry is now enabling to produce the reliable and safe transformers. Performance
evaluation during ability to withstand short circuit test in a fully equipped testing laboratory is still
final measure of checking the overall quality of the transformer from the point of design, material
used, production process and quality control. Central Power Research Institute (CPRI), is having an
experience of more than fifty years in the field of short-circuit testing. The roles of various factors
which affect the performance of transformers under short-circuit conditions are discussed along
with the analysis of the failure cases during the short circuit testing.
Harmonic Problem due to Saturable Devices in Steel Re-rolling Plant: A case study
Vasudeo B. Virulkar and Mohan V. Aware
This paper investigates the causes of harmonic norms violations in the medium scale (less than 2
MW load) re-rolling industry paying for the penalty. The major drive motor in this industry draws
the heavy current with deep in the voltage at the terminal of the motor when steel bars are re-rolled
with steps passes. To overcome the problem of voltage deep, the taps of the distribution transformer
supplying these loads are selected on higher side. This situation leads to the over excitation of
the transformer during the light load condition (between the passes) of the re-rolling operation
resulting the operation of transformer in nonlinear zone. During this operation the harmonics due
to saturation are generated and injected into the distribution systems and are the cause for damages
to the capacitor banks. This problem is analyzed by mathematical modeling of the load condition
with the transformer. The site investigation is carried out using power analyzer Megger-PA-9 plus
V604 and supported by the simulation in PSCAD/EMTDC. This investigation leads to suggesting
the remedial measures which is implemented to accommodate the harmonics inconformity with
IEEE-519 standard.
Vol. 7, No. 2, September 2011
Parallel Contingency Analysis for Power Systems Operation and Planning
G. A.Ezhilarasi and K. S.Swarup
This paper proposes a parallel processing approach to contingency analysis (CA) for power system
security evaluation. Full AC power flow analysis is done for each contingency and violations
of bus voltages and line flows are evaluated. All possible line outages are considered to avoid
overlooking of certain critical cases. Parallel Processing is employed to increase the speed of
execution. Parallelism is achieved by sharing each contingency across processors. The proposed
methodology is implemented in a Linux Cluster. Data communication is performed through the
Message Passing Interface (MPI). The effectiveness of parallelism is demonstrated by performing
contingency analysis on standard IEEE Systems. The performance of the algorithm is analyzed in
terms of computation speed and efficiency in comparison with the sequential approach.
Operational Optimization of Turbo Generator Units and Auxiliaries in Large Run-off
the River Hydro Power Plants
S. Jothibasu
This paper presents the operational optimization to be implemented, based on the energy
performance evaluation study carried out in a few large run off the river hydro power plants. The
design parameters are compared with operating parameters and the deviations are analyzed. The
various operational optimization opportunities available are described in this paper.
Application of Directional relay in an Ungrounded Power System to Locate Single line
to Ground Fault.
P. Vinod Kumar and Khyati Prajapati
To locate the ground fault in an ungrounded power system is very difficult and challenging
problem. The single phase to ground fault currents in these systems are much smaller than the
required magnitude of ground fault detection devices to operate. It is also important to isolate the
single phase to ground fault before restriking of second ground fault on the system to prevent a
possible double phase to ground fault. Ungrounded power systems have an advantage of continue
the operation with single phase to ground fault but it is also desirable and important to locate
and isolate faulted feeder of the system. This paper addresses the potential of identifying faulted
feeder by using a high sensitive directional relay which determines the fault current direction in
the ungrounded power systems. A MATLAB SIMULINK model is developed for ungrounded 11kV
three feeder power system. Single phase to ground fault is created in each feeder and it is detected
by directional relay.
Vol. 7, No. 2, September 2011
Application of NSGA-II in solving Multi-objective optimal power flow
T.Malakar, S.K.Goswami and A.K.Sinha
This paper is an application of NSGA-II for solving multiobjective optimal power flow problems
in power systems. Objective function considered in this work are conventional quadratic and
emission along with highly non-linear objectives like cost curve with valve point loading and cubic
emission function etc. In addition, more than two objectives are optimized simultaneously. The
problem is formulated as mixed integer one with both continuous and discrete control variables.
The performance of the proposed algorithm has been tested on three different IEEE test systems.
Results for the test system-1 have been validated with the reported works. The comparison is done
with the classical weighted sum method for IEEE 30 bus system and further experimentation is done
on two other test cases such as IEEE-57 bus and IEEE-118 bus systems. The results demonstrate
the effectiveness of the proposed approach for finding the Power System optimal solutions even
when more than two conflicting objectives are considered simultaneously.
Synchrophasor assisted Fault Diagnosis using Support Vector Machine
Paavani P., Singh S. N. and Srivastava S. C.
This paper presents a Support Vector Machine (SVM) based fault detection, classification and
location using synchrophasor measurements obtained from the optimally placed Phasor Measurement
Units (PMUs) for ensuring fault observability. An Integer Linear Programming (ILP) based PMU
placement method is proposed, considering the minimization of installation cost as objective with
line observability as its constraint. The breaker and half bus-bars scheme is considered at one
of the substations to show its impact on the Optimal PMUs Placement (OPP). After the OPP, a
SVM based post-fault studies are carried out using the synchrophasor measurements, available
from the PMUs. Three types of SVM-Classifiers (SVM-C) are used for the fault detection, faulted
line identification and the fault classification. Further, fault location is carried out using Support
Vector Regressor (SVR) in which four SVMs are utilized, one for each fault type. The same
classification and regression is carried out using Radial Basis Neural Networks (RBFNNs) and the
results obtained from SVM are compared. The performance of the proposed method is studied on
WSCC 9-bus system with and without consideration of the breaker and half bus-bar scheme and
on New England (NE) 39-bus system.
Optimal Placement of Power Quality Monitors
D. Saxena, Sayak Bhaumik, S.N. Singhand K. S.Verma
Power quality is becoming a major concern due to increase penetration of power electronics devices
and smart grid initiatives. This paper presents an effective methodology to optimally place the Power
Quality Monitors (PQMs) to get complete information of the network even under the some outages
which makes the system completely observable. Binary Particle Swarm Optimization (BPSO)
technique has been used to minimize the numbers of PQM required to make system completely
observable and to maximize the measurement redundancy. An index based two-step method has
been proposed. Simulation result of the proposed method on IEEE 14 bus system, IEEE 24-bus
system IEEE 30-bus system, 13-bus feeder system, 34-bus feeder system, 37-bus feeder system are
presented to demonstrate the suitability of the proposed method.
Vol. 7, No. 2, September 2011
Structure Property Correlation and Evaluation of Tensile Properties of Cenosphere
Aluminium Composites
Prashanth T., K.Narasimha Murthy and C. K.Umesh
The automobile and aerospace industries relenting passion to enhance the performance of commercial
and military applications is constantly driving the development of improved high performance
structural materials. Composite materials are one such class of materials that play a significant
role in current and future aerospace applications. Composite materials are particularly attractive
to both automobile and aerospace applications because of their exceptional strength and stiffness
to density ratios and superior mechanical properties. Cenospheres are hollow alumino-silicate
microspheres from fly ash of thermal power stations and are a valuable industrial product due to
successful combination of their technical and commercial parameters and can be used as a creation
of functional materials. This paper discusses the use of cenospheres as reinforcement in the casting
of aluminum metal matrix composite. Based on the metal, reinforcing phases, respective ratios,
fly ash cenospheres – aluminum composite with better features in terms of density, strength and
hardness have been developed
10. Foreign & Indian Experience In Policy And Regulatory Issues and Challenges for
Private Investment in the Indian Power Sector
I.P.S. Paul and SK.Choudhary
The power sector in India is dominated by the State and Central Government sectors accounting
for 44.57% and 30.83% of the generation capacity respectively while the private sector accounts
for about 24.58% as on 31.01.2012.The bulk of the transmission and distribution functions are with
State utilities. The private sector has a small but growing presence in distribution and is making an
entry into transmission. Power Sector which had been funded mainly through budgetary support
and external borrowings was opened to private sector in 1991. Electricity is considered key driver
for targeted 8 % to 10% economic growth of India. The vast Indian power market, today offers one
of the highest growth opportunities for private developers.
11 Coordinated bidding strategy of a supplier in day-ahead and balancing energy market
A.K. Jain, S.C. Srivastava, S.N. Singh and L. Srivastava
This paper presents a methodology to develop an optimal coordinated bidding strategy of a supplier
in Day-Ahead Energy Market (DAEM) and Balancing Energy Market (BEM). It is assumed that each
supplier bids hourly price-volume bid in DAEM and BEM (for up regulation and down regulation)
for 24 hours. In this work, a bi-level optimization problem has been proposed to obtain the optimally
coordinated bidding strategy of a supplier, considering rivals’ bidding behavior, inter temporal
constraints, and multi period auction. Lower level problem represents the market clearing process of
System Operator (SO), in which DAEM and BEM are cleared separately and sequentially for all the
24 hours. Upper level problem represents the supplier’s profit maximization function, which is nonlinear. Therefore, Artificial Bee Colony (ABC) algorithm, a modern heuristic approach, has been
used to obtain the best solution of the proposed bi-level optimization problem. The effectiveness
of proposed method has been tested on modified IEEE 30-bus system. Results obtained using the
ABC algorithm has been compared with those obtained using a Genetic Algorithm (GA) based
approach. To illustrate the effect of coordinated bidding strategy on supplier’s profit, results of the
coordinated bidding strategy have been compared with those obtained by uncoordinated bidding
Vol. 7, No. 2, September 2011
12. Simulation and Experimental Verification of Alternating Current Electric Arc
Furnace with Static Var Compensator
Janak J. Patel, H. R.Jariwala and AnkurVashi
Non-linear and erratic loads like an alternating current electric arc furnace with almost instantaneous
fluctuations with its active and reactive power requirements, leads to power quality issues such as
poor power factor, harmonic generation etc. We propose to simulate such unique load and prepare
its simulation for active and reactive power requirements. Static var compensator is perfect solution
for eliminating the above mentioned threats to power quality. SVC behaves like shunt connected
variable impedance, which can either generate or absorbs reactive power. [2] Through this review
we also present simulation of SVC with AC EAF and prove that all reactive power required by
AC EAF during its operation at various power stages is supplied by the SVC only and net reactive
power drawn/supplied from system is almost zero in line with actual field practice.
Vol. 8, No. 1, March 2012
THE JOURNAL OF CPRI - Vol. 8, No. 1, March 2012
Optimization of Grading Ring of 624 kV Zinc Oxide Surge Arrester using Finite
Element Technique
M.Kanyakumari, R.S.Shivakumara Aradhya, B. Rajaiah, S.Kondala Rao
Zinc oxide (ZnO) surge arresters are being used extensively in high voltage power systems for
providing protection to the transmission lines and the associated substation equipment from over
voltages caused due to lightning and switching surges. It has been observed in practice that the
voltage distribution in a tall multi section arrester under normal operating conditions is quite nonuniform. As a result, the ZnO blocks at the top section share higher voltage and hence higher
thermal stresses than the ZnO blocks at the bottom section. This leads to accelerated thermal ageing
of the blocks at the top if proper measures are not taken to make the voltage distribution uniform
along the entire length of the arrester. Generally provision of grading rings is a common method for
achieving uniform voltage distribution through out the length of arrester. In this paper, the results
of the optimization of the grading ring dimensions for a 765kV system arrester with a rated voltage
of 624 kV using Finite Element based 2-D Elecnet software is presented.
Developments and Challenges in Substation Automation
K. Yashwant and K. S. Swarup
This article looks at the development of substation automation systems and associated issues and
challenges. The new but already quite popular IEC61850 based substations automation systems are
discussed. The issue of interoperability which has been remarkably solved by IEC61850 has also
been discussed. Additionally, issues and challenges associated with implementing these substation
automation systems have been discussed.
On-Line Diagnosis of Power Transformer Insulation System Experience of CPRI,
H N Nagamani, T Bhavani Shanker
Power transformers play a vital role in handling large amount of power from generating stations
(through generating station units-GSU) to transmitting stations (through power transformers)
and to end user through distribution transformers. Power Transformers involve large amount of
capital investment and the failure of transformers causes severe financial loss to the utility and
inconvenience to the end users. Periodic maintenance and condition monitoring are the key factors
for successful operation of power transformers. A number of diagnostic tools are in vogue. Most
of these tests are conventional off-line techniques and require power shut down and disconnection
of transformer from the circuit. Several alternate non-conventional on
-line techniques are being adopted and acoustic emission (AE) technique is one among them.
Central Power Research Institute (CPRI), India, is employing AE technique for on-line diagnosis
of Power Transformers. Nearly 200 transformers have been tested and investigated covering rating
up to 315 MVA, 400 kV.
Vol. 8, No. 1, March 2012
The paper discusses some of the important aspects of on-line diagnosis of oil filled power transformers
employing AE technique. A few important case studies which have helped utilities and transformer
manufacturers for initiating corrective actions are covered in the paper.
Investigation on Polarization – Depolarization Current Measurements in Insulation
Systems for High Voltage Motor
Tapan M Rami and Prasanta Kundu
This Paper presents the assessment of insulation systems for high voltage induction motor through
measurement of Insulation Resistance, Polarization Index and Polarization-Depolarization Current
or Charging and Discharging current. It is considered that the insulation systems are having
different types and conditions of insulation aging. It demonstrates that the Insulation Resistance
(IR) and Polarization Index (PI) cannot be used individually to judge insulation dryness and the
combination of insulation resistance and Polarization and Depolarization Current (PDC) analysis
is better technique of insulation quality assessment than the insulation resistance alone. The
Polarization and Depolarization Current analysis is non destructive dielectric testing method for
determining the conductivity and moisture content of insulation materials in high voltage motors.
On the basis of this analysis, it is possible to take further actions like overhauling, drying process,
and replacement of the winding of the motor. This paper also presents a description of Polarization
and Depolarization Current analysis technique with the practically and theoretical background and
some results of Insulation Resistance, PI and Polarization and Depolarization current measurements
on High voltage motor.
Analysis of Transformer Insulation by Tan Delta testing Method
Dipak Mehtaand Hitesh Jariwala
This paper presents analysis of power transformer insulation by one fundamental insulation Power
factor test, also known as Tan Delta. It is a routine test conducted at site to know the healthiness
of insulation in transformers. Total 108 no’s transformer tested for research work, out of them
5 no’s case study chosen for analysis purpose. Experimental data shows our experience on the
measurement of Tan Delta techniques of earthing systems and dryness of insulation in transformers.
Result shows that the Tan Delta testing method is very efficient method.
Optimization of Air Insulation Clearances for EHV/UHV Transmission Lines
Pradeep M. Nirgud B. Gunasekaran R.S. Shivakumara Aradhya
This paper presents the results of the study conducted on 400, 800 & 1200 kV transmission line
insulator strings and conductor – tower window geometries with an aim to optimize air insulation
clearances. Laboratory investigations were carried out to evolve the switching impulse performance
of phase – to – earth and conductor-window configurations in addition to the reference rod plane air
gap lengths in EHV/UHV range. Tests were conducted on 400, 800 & 1200 kV line configuration
of I, Vee, double Vee etc., by simulating the tower windows. The paper also presents results of
the study on optimization of conductor-tower air insulation clearances for adoption in 1200kV AC
transmission lines using 8 bersimis conductor bundle carried out for establishment of 1200kV Test
Station at BINA, Madhya Pradesh by Power Grid Corporation of India. Results of the tests & the
data presented in the paper will be useful for design of phase-to-ground air insulation for adoption
in EHV/UHV Transmission lines.
Vol. 8, No. 1, March 2012
Measurement and Control of Electrical Energy For The Efficient Energy
Manish Kumar Ghodki
“Measurement and Control of Electrical Energy for the Efficient Energy Management” is based on
smart energy metering which has its own distribution, controlling and monitoring system for the
amount of electrical energy (KWh). It is also equipped with the control of alternative source of
electricity (solar energy). This hardware project measures the electrical energy (KWh) as well as
controls the amount of electrical energy from supply to load during day and night automatically.
The measurement can be performed up to ten lac (10,00,000) units and controlling can be up to
two lac (2,00,000) units with a unit range selection of 0 – 20 units and 20 – 2,00,000 units. In
the controlling part, when the energy consumption from the mains supply exceeds the preset limit
then the mains supply will be automatically tripped and the project provides the alternative power
supply in the absence of this mains supply by using the renewable (solar) energy source.
Operational Optimisation of Boilers in Coal Fired Base Load Thermal Power Plants
N. RajKumar
This paper describes the performance analysis of steam generators. Various energy conservation
measures such as operating excess air level control and insulation condition and its impact on
overall heat rate of a thermal power station is discussed. Study results show that the change in
operating oxygen level in flue gas can give benefit in unit heat rate to the tune of 10 – 40 kcal/kWh
in 210 MW units and 10 – 50 kcal/kWh in 500 MW units. Reduction in the boiler skin temperature
from 30 °C to 10 °C above the ambient dry bulb temperature will result in improvement in unit
heat rate by 60 kcal/kWh in 210 MW units and 80 kcal/kWh in 500 MW units.
Heat Rate Improvement in Utility Power Plants through Steam Turbine Performance
N. RajKumar
This paper describes the performance enhancement of steam turbines. Various energy conservation
measures such as steam path audit, vacuum improvement in condenser, turbine retrofits, feed heater
performance improvement, etc are discussed. Study results show that the improvement in operating
turbine efficiency will lead to a quantum improvement in unit heat rate from 25 to 225 kcal/kWh.
10. Enhancement of Energy Efficiency of hydro Turbine Generators by energy conservation
Rajashekar P. Mandi and Udaykumar R Yaragatti
This paper describes the results of enhancing energy efficiency of hydro turbines by implementing
the energy conservation measures for hydro turbine generators. The procedure for evaluating the
on-line performance of generators is discussed. The energy saving in generators by maintaining
optimum generator terminal voltage, by reducing the stator winding temperature by improving the
performance of coolers and reducing the excitation loss by appropriate tuning of excitation system
are enumerated in details with case studies. The implementation of energy conservation measures
have a techno-economic feasibility with a payback period of 1 to 5 years.
Vol. 8, No. 1, March 2012
11. Erosion resistance of Chromium – Manganese iron alloy cast in metal and sand
moulds: PLS & DBAR studies
P. Sampathkumaran, C. Ranganathaiah, P. K. Pujari, S. Seetharamu and Kishor
The wear resistant high chromium (Cr: 16 – 19 %) iron alloyed with 5 % and 10% manganese (Mn)
were produced in metal and sand moulds by induction melting technique. The erosion resistance,
hardness and microstructure were evaluated both in the as-cast and heat treated conditions. The
advanced non-destructive test (NDT) methods namely Positron Lifetime Spectroscopy (PLS) and
Doppler Broadening annihilation radiation (DBAR) studies using variable energy positron beam
were made use of to study the influence of metallurgical parameters on the defect sensitivity in the
bulk and surface of the alloy. The data reveals that as the mould type is changed from metal to sand,
the hardness decreases irrespective of the sample condition (i.e., as-cast or heat treated), whereas
the erosion volume loss shows an increasing trend. The light and scanning electron microscopy
give good support to these data findings. It is observed that faster the cooling rate (metal mould),
finer is the carbide size precipitation on the surface of the sample. The PLS data reveals that the
defect size and its concentration are higher for sand mould alloy compared to metal mould. The
reasons for lower erosion loss and fewer defects of smaller sizes in metal mould are attributed to
faster heat transfer in the metal mould compared to the sand mould. Further, heat treatment of the
samples yielded spherodization of carbides in the matrix and some of the defects seem to have been
annealed out leaving only fewer defects of smaller size in the alloy. The S-parameter profiles of 10
% Mn both in AC and HT samples are almost identical indicating near absence of any modification
of defect structure near the surface following heat treatment in 10 % Mn sample while 5 % Mn
samples exhibit less defect concentration both at the surface as well as in bulk which agrees with
the PLS results. Hence, the 5 % Mn bearing metal mould sample in the heat treated condition is
preferred choice as it shows higher hardness, lower erosion loss as well as least defect concentration
with smaller defect sizes. Based on this investigation, a good correlation among erosion loss, DBA
and PLS data has emerged.
12. Stack Optimization of Thermo acoustic Refrigerator
B.G. Prashantha, M.S. Govinde Gowda, S. Seetharamu andG.S.V.L. Narasimham
The performance of the thermoacoustic refrigerator depends upon a very large number of parameters
and hence the components are optimized using linear thermoacoustic theory to restrict the number
of variables by dimensionless normalization technique. Since the stack is considered as the heart
of the thermoacoustic refrigerator, the stack design parameters are the most significant parameters
for the optimal overall performance. The stack optimization result shows that a decrease in stack
length and center position from the loud speaker increases stack performance. Determination
of optimum stack length and center position helps in designing the refrigerator and to provide
adequate space for instrumentation in practical work. The cross-sectional area of the stack and
hence the stack diameter is calculated for the required cooling load capacity which is considered
as the basic parameter on which the design of other components depends. The effect of mean
temperature of the gas has not received attention in the literature and hence the performance of
the stack at higher mean temperature of the gas is theoretically evaluated.The improvement in the
stack coefficient of performance COPs is reported compared to published experimental optimization
studies at the design conditions considered in this paper and the results are in good agreement with
past established work.
A Golden Jubilee Edition, Vol. 8, No. 2, 2012
THE JOURNAL OF CPRI - A Golden Jubilee Edition, Vol. 8, No. 2, 2012
Central Power Research Institute: Over Five Golden Decades of Dedicated Service to
the Nation
Central Power Research Institute (CPRI), an autonomous Society under the Ministry of Power,
Government of India was set up in 1960. The Institute has rendered over five decades of dedicated
service to the Power Sector. The paper details the journey of CPRI from its inception, establishment
of state-of-art specialized R&D and Testing Facilities viz. Short Circuit testing, High Voltage testing,
Power System studies, Power Cables and accessories, Energy meter, Design of Transmission Line
Towers and testing, Conductor Vibration Studies, Transformer Oil, Power Capacitors, Solar and
LED Lighting Systems which has resulted in recognizing CPRI as one of the largest Research and
Test House in the world catering to the entire gamut of services covering Generation, Transmission
and Distribution under one roof. The decades witnessed the expansion of CPRI activities and
besides Bangalore and Bhopal, CPRI Units were established at Hyderabad, Nagpur, Noida, Kolkata
and Guwahati. Pioneering Research work aiding the Utilities and Industry and expansion of Field
testing, Consultancy/System studies, Monitoring and Inspection achieved a healthy growth. The
Institute during these years was able to enhance its brand equity and cater to the requirements of
the Overseas Customers.
R&D Efforts of CPRI: Sustenance of Technologies and Focus on Challenges for the
With its state-of-the-art infrastructure and expertise, CPRI has made significant contributions to
the power sector in the country for improved planning, operation and control of power systems.
Besides in-house R&D, CPRI also undertakes sponsored research projects from manufacturers
and other agencies in different areas of specialization in Power Engineering. CPRI has completed
50 years of dedicated service to the Indian power sector. With a humble beginning in the year 1960,
CPRI has grown from strength to strength and today it has a major role to play in all the ambitious
plans, projects, schemes of Ministry of Power, Government of India. CPRI under the guidance, support
and encouragement of Ministry of Power, will forge ahead to serve the Indian Power Sector in a
big way. CPRI also looks forward to work in close cooperation with the Indian Power Industry and
the Academia for achieving the economic growth and prosperity of the country.
A Golden Jubilee Edition, Vol. 8, No. 2, 2012
Centre for Collaborative and Advanced Research
This center established in CPRI, Bangalore is aimed to function as a center of excellence in
collaborative and advanced research in the power sector. The infrastructure for electric power
generation, transmission and distribution is aging and requires significant research and development
and the introduction of new technologies. Talents and strengths of CPRI based scientist and engineers
will be used to close the gap between fundamental research and pre-commercial development
Each technical group will focus on a key area in the power sector and provide a network
of coordinated research activity through collaboration with national and international laboratories
and industries. The main aim is to encourage an integrated approach to innovation through cross–
disciplinary projects. Using the combined technological capabilities of CPRI and other agencies, it is
aimed to generate cutting edge research that can be quickly translated into practical application.
This center of excellence would also provide the education and training necessary to create
and maintain an educated work force for fields currently experiencing personnel shortages. In
response to the shortage of engineers and scientists in areas of power generation, transmission,
distribution and utilization a comprehensive educational and research program is required. CCAR
infrastructure must be more effectively utilized to provide education and training and support
continuing education programs.
The Center for Collaborative and Advanced Research (CCAR) would have a research
consortium that includes universities and other research organizations. The goals of CCAR are
to create an environment in which universities, industry and R&D institutions work together to
promote and enable collaboration, to provide a forum for exchange of information and ideas, and
to create solution to complex and diverse problem facing the electrical power industry. CCAR is
especially interested in technical problems associated with the new institutional arrangements that
are occurring under a restructured regulated power industry.
The aim of CCAR is to promote research cooperation with industries in the fields of power
system, power electronics etc. The institution – industry consortium can further integrate the
research and education resources within CPRI and serves as a platform for research collaboration.
CCAR will also cooperate with other power engineering related institutes to advocate these fields
of study and boost participation of research scholars.
To exchange views on need based research programmes between the R&D institution
and industries, CCAR shall organize the annual review meeting and short courses on various
topics. Engineering from industrial partners can participate in these events to catch up on the latest
development of power technologies, and also to visit the laboratory facilities of the CPRI to see
the progress of the research work.
A Successful Journey of Fifty Years: Switchgear Testing and Development Station,
As a member of CPRI family, the Switchgear Testing and Development Station, Bhopal has become
an independent knowledge leader of high quality services, research and development. From a small
entity at the beginning it has developed to cater the requirement of Testing and Certification needs
of Electrical Equipments manufacturers and utilities in India as well as foreign countries within five
decades. This article briefs about features of different STDS laboratories and their growth from the
grass root level. Some of the nostalgic memories are also shared upon.
A Golden Jubilee Edition, Vol. 8, No. 2, 2012
Growth and Contribution of The High Voltage Division
The High Voltage Laboratory at Bangalore was initiated around 1964 in the campus of Indian
Institute of Science, also called as Tata Institute. the period between 1978 and 1983 in the history
of the High Voltage Laboratory of CPRI could be termed as very productive in building up the
expertise in R&D, testing and consultancy that paved way for formulating a road map for ensuring
a bright future for the high voltage engineering in CPRI. The activities of the division can we
attributed to EHV Test Laboratory (Main Laboratory), Mobile Field Testing Laboratory, Pollution
laboratory, Impulse Current Laboratory, Development of measuring equipment like Electrostatic field measurement instruments, High Voltage Test and Measurement Instruments and other
developments include Grading Ring for EHV/UHV Insulators and Surge Arresters, and Minimum
clearance requirement for transmission towers of 765 kV System.
Ultra High Voltage Research Laboratory, Hyderabad
Establishing an experimental UHV transmission line facility in India was undertaken, with funding
from Government of India, to carry out studies facilitating possible introduction of UHV lines
in the voltage range of 800–1200 kV AC of and to establish high-voltage test facility for the
development of equipment by Indian manufacturers and also for the purpose of quality assurance
testing of these apparatus. Research facilities at UHVRL have been set up mainly to undertake
major electrotechnical and biological research and development studies and also to undertake
testing activities for equipment ranging up to 1200 kV. The Impulse laboratory facilities available
at UHV Research laboratory, CPRI, Hyderabad are of world class and at par with international
laboratories like-CESI, EdF, KEEMA laboratories etc. Power equipment manufacturers, EHV/UHV
transmission grid operators and utilities can avail the services to evaluate their equipment and
sponsor the research work of their interest.
High Power Laboratory
To meet the growing needs of short circuit testing of switchgear and power transformers, the high
power laboratory was established in CPRI, Bangalore, in 1991. The laboratory was planned with
total installed capacity of 7500 MVA, which is to be achieved in three stages. In the first stage,
2500 MVA direct test facility with parallel current injection synthetic test circuit was installed.
The technical consultancy for the laboratory was provided by EDF High Power Laboratory, Les
Renardiers, France. The vital equipments of the laboratory, viz, short circuit generator, short circuit
testing transformers and the master circuit breakers and make switches, are specially designed with
essential technical characteristics required for short circuit testing of switchgear, power transformer
and other electrical power equipments. The laboratory is having the most modern measuring, control
and protection equipment. The short circuit and switching tests conducted in the laboratory are
strictly in accordance with IS, IEC, ANSI standards. The short circuit generator has been converted
into motorless system with state-of-art technology electronic controllers, which ensure trouble-free
testing service to customers from our country and abroad. The two decades of service rendered by
CPRI High Power Laboratory has resulted in quality-rich, reliable switchgear and power equipment
for the utilities and end users. The laboratory is providing continual service to nation building
activities in the field of power sector.
A Golden Jubilee Edition, Vol. 8, No. 2, 2012
Short Circuit Laboratory
The original set-up consisted of 12 kV 50 MVA Short-Circuit (SC) Generator driven by 3.3 kV
induction motor and a DC shunt generator coupled to the Generator shaft. Set-up also consisted
of auxiliary equipment like Air-blast Master Circuit-breaker for breaking the short-circuit current
and a high speed Make Switch for initiating the short-circuit, protection system for drive motor
and Generator, Control Desk, Measuring/recording system, etc. As there was demand for the DC
Short-Circuit test from the various manufacturers 600 V, 30 kA DC short-circuit test facility was
created under 8th Plan capital project. This is the only unique DC short-circuit test facility available
in India even today for testing LV DC equipment like MCBs, MCCBs, switches, contractors,
fuses etc. An impulse test facility for up to 30 kVp was also created for carrying impulse tests
on LV equipment. The laboratory contributed a lot in the indigenous development of HRC fuses
and Moulded Case Circuit Breakers with electronics trip circuits by English Electric Company,
indigenization of Circuit Breakers used in completely self-protected (CSP) transformers, mediumvoltage vacuum contractors, etc.
Insulation Division
The Insulation Division was founded to promote R&D activities related to power industries. The
Division gradually created facilities to undertake R&D, Evaluation studies on insulation materials.
Many research Projects were conducted encompassing vast area of electrical insulating materials.
A few notable among them are evaluation of electrical varnishes, motorett Coils, impregnated
electrical paper. Institute has also executed several accelerated aging projects, which include
acceleration studies on different classes of insulating materials such as (i) Class B, (ii) Class H
and (iii) Class F. Presently the Division is providing field services for RLA of power station and
substation equipment. Apart from other reachers activities.
10. Evolution of Diagnostic Laboratory
The Diagnostic, Cables and capacitors Division (DCC Division) formerly known as Cables and
Capacitors Laboratory (CC Laboratory) during 1970’s was mainly involved in testing of low voltage
(LV) and medium voltage (MV) cables, LV capacitors and heat run testing of bus bars/ducts, panels
as per National/International Standards. During 1980’s with the induction of young engineers and
scientists the laboratory initiated R&D projects related to the functional evaluation of insulation
systems of power cables, power capacitors, rotating machines, traction motors and the like. The
decade 1990 was remarkable from the point of view of diagnostic on-site testing and Remaining
Life Assessment (RLA) studies on power plant electrical equipment. As there was no established
diagnostic testing method for condition assessment of power cables, DCC Division introduced for
the first time in the country Very Low Frequency (VLF) tan delta testing for diagnostic testing of
XLPE power cables. The DCC Division conducted the VLF tan delta testing on 33kV class XLPE
cables at Rourkela Steel Plant in 2007 and detected the manufacturing defects in the cables.
11. Evolution of Insulation Materials Laboratory
The details about formation of Insulating Materials laboratory, its comprehensive growth over five
decades, in research, testing and consultancy areas is presented in this article. This write up covers
the historical perspective, research contributions including product development, various national
and internal committees represented and allied.
A Golden Jubilee Edition, Vol. 8, No. 2, 2012
12. Power Cables Laboratory
This paper presents bird’s eye view of contribution made by Power Cables Laboratory of CPRI
during the Golden Jubilee period 1960–2010 towards research, testing and certification. The
laboratory started way back in 1960 at the Indian Institute of Science campus, Bangalore with bare
minimum test facilities. The laboratory assisted many of the Indian cable industries by providing
consultancy and testing services for improvement and produce better quality cables. Over the years
the laboratory has been augmented with the state of art test facilities for research and qualification
tests on power cables and materials. At present, CPRI has state art of facilities for testing of
cables and accessories of voltage rating up to 220 kV rating. CPRI is setting up facilities for Prequalification testing of 400 kV EHV XLPE Cables as per IEC-62067. With this facility, CPRI test
facilities will get enhanced to type testing and pre-qualification tests of cables up to 400 kV voltage
rating. The research activities undertaken in this laboratory during this period is summarized.
13. Power Capacitors for AC Power System Application
Central Power Research Institute, Bangalore, is playing an important role in the development
of the capacitor industry by providing required facilities for research, testing and evaluation of
power capacitors. With the help of these facilities, all types of power capacitors, like all film
capacitors, composite dielectric capacitors, metallized film capacitors, etc. are being tested and
evaluated. In addition to facilities for routine and type testing of power capacitors according to
the IS Standard, sophisticated and expensive equipment for conducting more stringent tests like
Endurance test on full-size capacitor units up to unit rating of 1 MVAr and partial discharge test
based on advance acoustic emission technique are available in the Capacitors Laboratory of CPRI,
Bangalore. Facilities for testing high voltage series capacitors have been developed including
discharge current test, disconnecting test on internal fuses and cold duty test. In the field of LV
capacitors, special test facilities for charge-discharge and destruction test have been augmented to
meet the requirements according to the revised IS:13341-1992. Test facilities are also available
according to the UL safety requirements. Capacitor manufacturers in the country and from abroad
are availing the facilities of CPRI. Experience of CPRI during testing of different types of LV and
HV capacitors of unit rating ranging from 1 kVAr to 1118 kVAr for the last 10 years for will be
covered in the paper. Some of the important issues like (a) factors influencing the capacitor losses,
(b) influence of dissipation factor on the performance of LV capacitors during 1500 hours aging
test, (c) performance of full - size HV capacitors under cyclic over voltage applications at different
lower temperature limits, (d) operation of internal fuse, (e) testing of special capacitors for space
applications, (f) factors influencing discharge current characteristics for series capacitors, and (g)
acoustic emission technique as one of the NDT methods for performance evaluation, etc. will be
discussed in the paper.
14. Power Systems Division
Power system division carries out Power System Planning, operational studies, relay coordination
studies, power system grounding and earth mat design. Power systems division with its state of
the art facilities and latest software tools offers a wide range of power system simulation services,
including real time performance analysis of various types of controllers such as FACTS, HVDC,
SVC and protection relays. It has been conducting studies for the past two decades for its own
needs and at the request of utilities, manufacturers and end users of electric power. To carry out
such studies the division posses Real Time Digital Simulator, E-Megasim electric power system
simulator and different off line power system analysis software packages like SIMPOW, NEPLAN,
EMTDC, etc.
A Golden Jubilee Edition, Vol. 8, No. 2, 2012
15. Distribution Systems Division
The Distribution System Division (DSD) was established in CPRI in September 2008 and has a
team of professional engineers with vast experience in offering consultancy in Power Distribution
System for Utilities and Industries. With the state-of-art facilities and software tools, the Division
has been rendering consultancy services in finding solutions to various problems faced by the
Electricity utilities and industries in the area of power distribution. The consultancy services are
extended to the Electricity Regulatory Commission in estimation of losses in Distribution networks
in various states.
16. Utility Automation Research Centre
UARC division has a very long and interesting history in CPRI. In the very beginning after CPRI
was established, CPRI started using computers for solving electrical power systems and structural
engineering problems. The journey of computers in CPRI started during early 1960’s with the
development of computer programmes on the first and oldest computer in Bangalore namely Elliot
803 at HAL. During the second decade i.e 1970–1980 the mainframe computer IBM 360/44 and
then DEC (Digital Equipment Corporation) 1090 which replaced IBM 360/44 in IISc were used
for power system, High voltage and transmission tower testing related problems. During fourth
decade i.e. 1990–2000 the IT infrastructure witnessed a phenomenal growth. Tens and hundreds
of Personal computers were procured and upgraded from time to time. Local Area Network was
created during 1997–1998. During the fifth decade i.e. 2000–2010 CSET division has come into
full pledged operation. The development of CPRI Automation System (CAST) started during early
part of 2000s aiming at the automation of workflow, testing and other support activities. The IT
in the form of, Intelligent Meters (IM) became a reality during early part of 2010. Followed with
this initiative “Conformance Test Laboratory” was established during 2004.2005. “Gyanshakthi”
a knowledge management and digital library intranet portal was launched during 2005 which
facilitated sharing and seeking knowledge among CPRI fraternity.
17. Material Technology Division - Overview and Way Forward
Materials Technology Division came into existence during the year 1985–1986 and is significantly
contributing to R&D, Testing and Evaluation, Consultancy Services and IPR. The division
is equipped with advanced and sophisticated materials evaluation facilities aimed at providing
technical services in the areas of materials for the power sector.
Considering the significance of the growth of scientific and technological advancements in
the power sector for generation, transmission and distribution including renewable in the country, the
division has focused its efforts in pursuance of the mission of the organization and the engineering
services provided in the area of condition monitoring, renovation, modernization and life extension
of power plant and equipment through diagnostic and life extension studies for achieving economy
and reliability in the power sector.
The text of the paper describes the overall growth of the division as well as its contributions
to other divisions / units and the Way Forward.
A Golden Jubilee Edition, Vol. 8, No. 2, 2012
18. Dielectric Materials Division
Dielectric Materials division has established an excellent reputation and is known all over the
country for its expertise in testing of insulating oils and also for diagnostic testing of materials for
their condition assessment. Presently, the division has a full-fledged laboratory infrastructure for
testing new insulating fluids to test according to the IEC 60296. Testing of in service oils according
to the IS 1866-2000 for condition assessment as well as diagnostic information. Division has also
basic infrastructure for testing Lubricating oils particularly fully equipped to test the turbine oils.
Division also has basic characterization facilities to evaluate polymeric materials.
19. Polymer Laboratory
Polymer Laboratory of CPRI was established during 1976 to cater to the needs of power industry
in terms of Research and Development, Testing and Consultancy works. The laboratory has taken
up good number of projects and completed successfully. Scale up studies have been done for
development work done on Flame Retardant Low smoke PVC based cable compound and Synthesis
of Novolak Resin for electrical applications. Project works have been completed which have
resulted in award of doctorate and Masters degrees for several workers from different Universities.
The laboratory has published several papers in International Journals besides papers presented
in National seminars & conferences in addition to several product developments resulted in the
form of patents. Technology development studies have been carried out for the patented product
developed by involving private industry and project was sponsored by Department of Scientific
and Industrial Research (DSIR) under PATSER scheme. The laboratory was also successful in
conducting few consultancy studies to satisfy the requirements of electrical utilities.
20. Regional Testing Laboratory, Noida
The Regional Testing Laboratory (RTL) at Muradnagar has been functional since 1992 to cater to
the growing needs of northern power utilities and industry. Due to the proximity and inconvenience
to the clients the unit has been shifted to Noida and the laboratories have become functional since
June 2009. The important facilities cover Cables Testing upto 33 kV, High Voltage Laboratory for
testing Insulators and Transformers and Transformer Oil Testing Laboratory. The new facilities for
testing of Energy Meter and Diagnostic Testing facilities have been created at the new centre. A
large number of clientele covering utilities and industry has been established over the years. The
unit is having ambitious plans of augmenting facilities for Diagnostic Testing and also set up new
facility to cover more products.
21. Regional Testing Laboratory, Kolkata
Regional Testing Laboratory Kolkata was set up in September 2006 with a view to cater to the
testing, certification and evaluation needs of electrical power equipment manufacturing industries,
utilities and consumer in the eastern region. It also acts as a liaison unit of CPRI with various
clients in the region and coordinates their test requirements which are beyond the scope of RTL,
Kolkata but within capabilities of Bangalore and other units of CPRI. The major power utilities
catered to by RTL in the region are PGCIL, DVC, NTPC, NHPC and state electricity boards of
Bihar, Jharkhand, Orissa, Sikkim and West Bengal. Thus, the objective of CPRI Laboratory in
Kolkata is to cater to the need of electric power utilities in the eastern region. A large number of
power utilities are already in operation in the region. There are 49 power generating stations, 31
and 72 sub-stations of 400 kV and 220 kV capacities respectively in the region. CPRI is having
ambitious plan to fulfill the need of test facilities in the region. The laboratory is going to take
up expansion in its facilities to accommodate complete oil testing including testing of new oils,
condition monitoring of substation equipment and studies on distribution transformers.
A Golden Jubilee Edition, Vol. 8, No. 2, 2012
22. Regional Testing Laboratory, Guwahati
The idea of setting up a Regional Testing laboratory in North East was conceived in 2005–2006.
The Government of Assam and especially the Assam State Electricity Board (ASEB) took a keen
interest in the project and with their sincere cooperation and necessary funding by the Ministry
of Power, Govt. of India, the idea of a Regional Testing laboratory materialized in Guwahati. On
20th July 2007, the official journey of the Regional Testing Laboratory, Guwahati was set off.
Apart from regular testing activities, the RTLG is also acting as a coordinating center between the
potential clients of this region and the other divisions of CPRI.
23. Thermal Research Center - A Hub for Knowledge Source in Thermal Generation
Thermal Research Center, a unit of Central Power Research Institute, is to carry out Research and
provide appropriate solution in the Thermal Generation.
This Center is recognized as “A Well Known Remnant Life Assessment Organization” for
carrying out RLA Study of Boilers in India, awarded by Central Boiler Board, New Delhi, for
conducting RLA Study of steam and process boilers under Indian Boiler Regulation 1950. Thermal
Research Center is providing services in the areas of Non-destructive and Destructive testing, Failure
analysis of power plant components, Condition assessment of power plant components, Condition
assessment of civil structures with the latest technology and advanced equipment available. This
Center has served almost all the power plants and other Industries of India in the last 18 years.
24. Energy Efficiency and Renewable Energy Division
Renewable energy especially solar, wind and biomass was recognized as the future energy source
for India during the late 1960s and 1970s. CPRI installed water pumping windmills as early as
1976. The CPRI began the work in energy efficiency in 1979 recognizing its importance to the
power sector. The work began with product development for energy efficiency and renewable
energy and branched out into consultancy services for energy audits and power plant engineering.
The developments is traced from 1976 till present and the salient achievements are the development
of PRIYAGNI (PRI-Power Research Institute) wood burning stove, one of the first designs of
compact fluorescent lantern, biomass gasifier and Stirling Engine. On the consultancy side the salient
achievement is the energy audit of thermal and hydro power stations across the country. The Division
has contributed in its capacity to the making of the Energy Conservation Act 2001, Electricity Act
2003, National Electricity Policy 2005 and all other major energy related legislation.
A Golden Jubilee Edition, Vol. 8, No. 2, 2012
25. Electrical Appliances Technology Division
Domestic Electric Appliances Testing facility was a part of Insulation Laboratory during 1976.
Further battery testing facility and Relay testing facility were added. An off shoot of this
activity was formation of a new Division called Distribution Division with main aim of taking
R&D activities in the Distribution System, Optimization studies and also caters to the testing
and certification of Domestic electrical appliances, batteries and Relays. During the period from
1985 to 1995, this division has added new facilities for testing of fans and also environmental
testing of panels, In mid nineties, the Distribution Division leaded to the formation of Electrical
Appliances Technology Division with main intension of Environmental testing of panels, testing
and certification of Domestic Electrical Appliances, Fans, Relays and Batteries. With the enactment
of Electricity Conservation Act 2001 and BEE’s prime program of Standards and Labeling of
Electrical Appliances, The Division has shifted its activity towards check testing of appliances viz.
Refrigerator, Air conditioner. TFL and Ceiling Fan under Standards and Labeling Program for star
rating. Many State of the art test facilities have been established in the Division for this purpose
and the Division is having ambitious plans for setting up of new facilities for testing of Motors and
also augment the existing facility to cover more products viz. T5 lamps, Refrigerators up to 2.5 m
high, Batteries of various types and also to increase the bench capacity for testing.
26. Instrumentation Division
Instrumentation Division (ID) was established during the year 1976 with an aim of identifying the
problems encountered by Power Utilities and Energy Meter manufacturers in the area of Generation,
Transmission and Distribution and also to provide consultancy services. Many problems were
identified by the division, developed and provide solutions. Some of the them are Cable fault
Locator, Earth fault Indicator for floating DC Control cables, Time Synchronizing Unit, Single and
Three Phase Static Energy Meters, Electronic Trivector meters, Powered Support Characteristics
Recorder for Underground Coal mines. Instrumentation Division has obtained Patent for Cable
fault locator and Time Synchronizing Unit while Earth fault Indicator for floating DC Control
cables, Single and Three Phase Static Energy Meters, Electronic Trivector meter Technology was
transferred to private entrepreneurs for commercialization. During the year 1995, it was decided to
it was decided to render services in new area i.e. Testing and certification. In 1995, Energy Meter
Testing Laboratory was established at a cost of ` 85 lakhs. The project was funded by Ministry
of Power. Energy Meter testing Laboratory was established with an aim to cater the requirements
Power Utilities as well as Energy Meter manufacturers. Subsequently calibration and Relay testing
Laboratories were added. During the year 1998, EMI/EMC Laboratory was added to Energy Meter
Testing Laboratory. With this facility, ID established full state of the art Technology for energy
meter testing under one roof.
Instrumentation Division also established Mobile Energy Meter Testing Laboratory during
the year 2007 with an objective to verify the performance of energy meter (In-service) at Consumer
premises on behalf Power Utilities or public Grievances Cell as the case may be. At present the
mobile energy meter testing lab is stationed at New Delhi.
A Golden Jubilee Edition, Vol. 8, No. 2, 2012
27. Vibration and Seismic Qualification of Products and Equipment
Vibration analysis and testing helps to accelerate progress in many industries, including aerospace,
automobile, Electrical equipment manufacturing, power generation, defence, consumer electronics
and telecommunication. Vibration tests are carried out to identify and eliminate unwanted vibration
to improve product quality and durability. Many standards have been evolved over the years to
prescribe suitable test procedures for qualifying the finished products and equipment. Earthquake
Engineering and Vibration Research centre (EVRC) is equipped with state-of-the-Art facilities to
carry out vibration and seismic tests according to the National and International Standards.
28. Mechanical Engineering Division - Design Cell
The Design cell at Mechanical Engineering Division was created in 1980’s with objective to support
the Tower Testing Station activities and take up the consultancy works on design of towers for new
transmission lines, analysis and checking of towers designed earlier for further optimization of
weight, checking the adequacy of existing towers for up-rating a line, redesign of existing towers
with least modifications for upgrading etc.
29. Mechanical Engineering Division - Tower Testing Station
The Mechanical Engineering Division established in 1976 and prior to this, the Model Tower Testing
Laboratory was also established and was operational. All though some of the tower manufacturers
have tower testing facilities and being captive in nature and not available to others in the field and
experiencing delay in commissioning of transmission projects, the Government of India decided to
setup a tower testing station under CPRI.
Based on the requirements and foreseeing the future power demand and forecast for
new power projects in the country, Prototype Tower Testing Station (PTTS) was established and
commissioned during 1976 (Inaugurated by Ministry of Power).
The station was opened to commercial tests as third party certification as well as for R&D
oriented tests with the concept of development of new designs in transmission towers and a full
fledged model tower testing laboratory was strengthened/established during 1982.
The requirement for testing other transmission components like conductors, insulators, etc.
Vibration Laboratory was established during 1978. Further, due to installation of new transmission
lines of higher rating of 400 kV and above, for studying the Vibration characteristics of hardware/
accessories Wake Simulation Laboratory established during 1985. Further, during the year 1990
Foundation Testing Centre was established.
Over the years the division has been augmented to facilitate higher category/rating of
transmission towers and its components in line with growth of power industry. CPRI is an R&D
Institute and for catering to the needs of utilities to facilitate the design, development and testing
of the various components of overhead transmission line system under one roof, the division
established a design and consultancy wing. The standardization of transmission towers, design and
analysis of transmission towers were facilitated since 1980.
A Golden Jubilee Edition, Vol. 8, No. 2, 2012
30. Mechanical Engineering Division - Vibration Laboratory
The Vibration Laboratory and Wake Simulation Laboratory are very oldest and unique in its
nature, were established in Mechanical Engineering Division in the eighties. These two laboratories
were come into existence under the leadership of Shri T.V. Gopalan who headed the Mechanical
Engineering Division nearly more than a decade. It would not have been possible to have such
a wonderful laboratory as stood up-front today than as it was seen before was probably with
able guidance and support from Shri C.S. Sreenivasan, who served the Institute as Director from
The Vibration lab was first established in the year 1980, while the Wake Simulation
Laboratory was subsequently came into existence after few years. Special thanks and credit goes
to Shri T.V. Gopalan, as Head of Mechanical Engineering Division for having constructed the WSL
at very low expenditure by using tested tower parts and employing the in house welders. As on
today and as things stand on, we are quite confident of offering our high ended services in terms
of product development, Research and testing not only limited to power sector but also to others.
31. A Bird’s Eye View of CPRI Library and Information Centre
The CPRI Library and Information Centre, Bangalore was established with the inception of the
Institute in the year 1960 with 400 books donated by CWPC. Over the years the library has grown
up in many folds and CPRI has established Digital Library, Knowledge and Information Centre.
Vol. 8, No. 3, September 2012
THE JOURNAL OF CPRI - Vol. 8, No. 3, September 2012
Experimental Investigation on Model Transformer Windings to Analyze Axial and
Radial Displacements
M. Prameela,G. Radha Krishna Murthy &Pradeep M. Nirgude
Sweep Frequency Response Analysis (SFRA) method is an efficient method for predicting the
geometric changes and research on the optimum and unambiguous application is still in progress. In
order to correlate integrity of transformer windings with changes in the frequency responses, lot of
measurements have to be performed and analyzed. The present work discusses special experimental
investigations carried out on model transformer winding to study the various aspects of axial
and radial winding displacements using SFRA test. The experimental results for axial and radial
winding displacements are presented and analyzed. The analysis will help in understanding the
health of an actual transformer and diagnosing it for any impending fault with respect to winding
A Comparison of PI Tuning by Direct Search and Genetic Algorithm for Optimal
Control of AGC in Continuous-Discrete Mode
Debashisha Jena, Mokenapalli Vijay
This paper deals with Automatic generation control (AGC) of interconnected hydrothermal system
in continuous-discrete mode using proportional-integral (PI) controller with different tuning
approaches. Here the PI controller is initially tuned using local optimization technique such as
Fminsearch (Existing MATLAB function) and optimal control strategies were taken as integral
square error (ISE), integral time-absolute error (IATE) and integral time square error (ISTE). Then
the same PI controller is tuned by using evolutionary algorithm i.e. Genetic Algorithm (GA).For the
given system appropriate generation rate constraint (GRC) has been considered both for the thermal
and hydro plants. System performances are examined considering 1% Step Load Perturbation (SLP)
in both thermal and hydro area with 1 second sampling period. Finally the performance of both the
local and global optimization algorithms is compared in terms of the time domain specifications
both for frequency deviation in each area, and tie line power.
DG placement in radial distribution network with reconfiguration
Tejas Vyas & Ranjit Roy
This paper presents a simple method for finding the optimal DG size and optimal DG location
in distribution network. By using this method optimal DG capacity and location is determined
considering without network reconfiguration and with network reconfiguration. The method is
tested with three test cases: 33-node, 69-node and 117-node IEEE standard network. Result shows
that the proposed method is very efficient and competitive with the existing methods available in
the literature.
Vol. 8, No. 3, September 2012
Design of artificial intelligence based load frequency controller for a two area power
system with super conducting magnetic energy storage device
R. Jayashree
Superconducting Magnetic Energy Storage (SMES) unit with a self-commutated converter is
capable of controlling both active and reactive power simultaneously and quickly, increasing
attention has been focused recently on power system stabilization by SMES control. In this study,
a self tuning control scheme for SMES is proposed and applied to Automatic Generation Control
(AGC) in power system. The system is assumed to be consisting of two areas. The proposed selftuning control scheme is used to implement the Automatic Generation Control for Load Frequency
Control (LFC) application adding to conventional control configuration. The effects of the self
tuning configuration with Artificial Neural Network (ANN) in AGC on SMES control for the
improvement of Load Frequency Control is compared with that of Conventional Integral controller,
PI controller, Fuzzy Proportional Integral Controller (FPIC). The effectiveness of the SMES control
technique is investigated when Area Control Error (ACE) is used as the control input to SMES.
The computer simulation of the two-area interconnected power system shows that the self tuning
ANN control scheme of AGC is very effective in damping out of the oscillations caused by load
disturbances in one or both of the areas and it is also seen that the ANN controlled SMES performs
primary frequency control more effectively compared to Integral controller, PI and FPIC controlled
SMES in AGC control.
Fuel & Cost Optimization of Grid Connected MTG-PV Based Hybrid System
Grishma J. Patel & ShabbirS. Bohra
A MTG-PV hybrid system is a reliable DG based system because PV is unpredictable non-traditional
energy source whereas, Micro-turbine is a controllable traditional energy source, which will cancel
out each other’s drawbacks. In this paper, a microturbine generation system (MTG) is considered as
the backup generation, to meet the energy requirements when solar energy is not sufficient. Main
objective of this paper is optimization of Fuel & Cost of grid connected MTG-PV hybrid system.
Analysis of power management & fuel optimization is carried out using the MATLAB/SIMULINK
platform. HOMER (Hybrid Optimization Models for Energy Resources) power optimization
software by NREL (National Renewable Energy Laboratory) is used to optimize the cost of the
hybrid system.
Comprehensive Study on Central Control Management of a Power Distribution
Subhashree Patra & K.S Swarup
The purpose of this study is developing a familiarity with the central control and management
functions, the nerve of any power system. The paper considers a distribution system and emphasizes
on a distribution management system (DMS). DMS uses state estimation to maintain the healthy
working condition of the system. It plays a very important role in the control of the distribution
system as the level of control possible is restricted owing to the specific structure of distribution
networks and penetration of real-time monitoring and control facilities. So far the level of SCADA
implementation in distribution networks has controlled around 10% of switching devices and has
been limited to circuit breakers at the larger primary substations. The four main functions of the
DMS have been discussed focusing mainly on Outage Management.
Vol. 8, No. 3, September 2012
Voltage Sag Mitigation in Three Phase Induction Motor using DSTATCOM and
B.V.Ramprasad & Khyati Mistry
Voltage sag in distribution system is one of the most frequently occurring power quality problem.
There are many solutions to mitigate voltage sag. This paper describes one such technique to
mitigate voltage sag occurring during starting of three phase induction motor by using power
electronic devices called Dynamic Voltage Restorer (DVR) and Distribution Static Compensator
(DSTATCOM). This paper is organized with brief introduction of voltage sag and its characteristics,
structure and control principles of DSTATCOM & DVR. The performance of both DSTATCOM
and DVR to mitigate voltage sag caused by starting of three phase induction motor is observed and
compared. The simulation models of both the devices are analyzed and results are shown.
Diagnostic Testing of Hydro & Turbo Generators andLarge AC Motors in service
K. Mallikarjunappa, Chandrashekar D. Keri, V. Vaidyanathan Thirumurthy, T.R. Afzal Ahmed
Majority of the generating sets operating in our country are turbo generators contributing nearly
70% of the total electrical power generated. Many of these generators are about 30-40 years old and
have already come to the end of their notional design life. In recent times, with the ever growing
demand for power, high cost of new equipment and paucity of funds there is an increasing trend
to upgrade and extend the life of older generating sets. It has been recognized that with the advent
of new technologies there is a scope for upgrading of generating capacity of the generators. In the
light of this, knowledge of integrity of these machines and their remaining service life would be
of great interest. In this, endeavor, there is a strong incentive for condition assessment of various
components of these machines. Over the years many diagnostic tests have been suggested for
condition monitoring of different components of the machines. The data obtained from these tests
provide much needed information regarding present state and condition of the components.
Seismic performance of 245 kV current transformer
Srujana N, Ramesh Babu & Katta Venkataramana
Substation equipment whose natural frequencies lie in the normal frequency range of earthquake
ground motion are particularly vulnerable to damage by seismic events. Electric power systems,
are expected to be functional during and after major earthquakes and it is vital to sustain economic
activities and assist recovery, restoration, and reconstruction of the damaged structures and equipment
during earthquakes. Current transformer (CT), usually having a narrow long porcelain insulator is
the most vulnerable part subjected to earthquake. This paper evaluates amplification factor in terms
of acceleration from the ground to top of the support structure where the current transformer is
mounted. Sine sweep tests are conducted on current transformer with support structure to evaluate
its dynamic characteristics using shake table tests. The ground motion amplification obtained from
finite element analysis and shake table tests is compared.
Vol. 8, No. 3, September 2012
10. Impact of ultra violet radiation on an artificially polluted silicone rubber during
inclined plane tracking test
S.Ganga, N.Vasudev, V.Asai Thambi, R.S.Shivakumara Aradhya & A.Sudhindra
This paper presents experimental results obtained on the tracking and erosion resistance of Silicone
rubber (SIR) with and without pollutants. The IEC 60587 Inclined Plane Tracking and Erosion
Test method combined with UV radiations of different intensities were employed to assess two
different formulations with same base polymeric material (SIR). The hydrophobicity recovery
property of silicone rubber formulations before and after inclined plane tracking test was studied
besides the effect of corona. Some of the physical, thermal and electrical properties were compared
before and after inclined plane tracking test. It is inferred from the analysis carried out on the
experimental results that, the intensity of UV radiation plays a major role in deteriorating the
surface characteristics of the material. It is also found that the introduction of UV in the test method
has helped, in distinctly evaluating polymeric materials. The effect of two different pollutants
was not the same on formulations considered for the study which implies that, the additives play
a dominant role in the overall performance of the material than the base polymer. The study also
revealed that a formulation with better performance under a certain pollutant need not behave the
same way under a different pollutant. As presently, CIGRE Working Group (WG D1.14) is active
in standardization of material aspects besides developing suitable methodology for the testing of
polymeric materials for outdoor insulation application, the inferences appear to be an useful input
to both CIGRE working group and International Electro technical Committee (IEC TC 15 PT 2).
11. Critical speed analysis of a single stage impulse type high-speed steam turbine rotor
B. Gurudatt, S.Seetharamu, P.Sampathkumaran, Vikram Krishna
Resonance is a common thread that runs through almost every branch of engineering.Yet, this
phenomenon often goes unnoticed, silently resulting in inconveniences, such as causing a bridge
to collapse or a helicopter to fly apart, to name a few. It is therefore of utmost importance to avert
resonance, for which determining the frequency of the system becomes indispensible. In complex
rotating structures, as one considered in this paper, theoretical determination of frequency is as
difficult and laborious as a task can be. Finite element analysis has proven to be an effective tool
to handle such a task. Resonant vibrations incited by the running speed harmonic excitations,
steam impinging frequency, engine order excitations are fundamental causes for failure of turbine
components. The mainstream discipline that is encompassed by this paper is the modal analysis.
Modal analysis is performed to estimate the critical speeds and study the mode shapes of the bladed
rotor disc under prestressed condition.
Vol. 8, No. 3, September 2012
12. Energy enhancement of plate shear line in Essar steel limited with advanced ac drive
B.K.Thummar, V.A.Shah, A.K. Panchal
This paper represents the comprehensive study, analysis and result achieved by data evaluation
of AC drive system over DC drive system in Essar steel Limited in India. With innovations in
advanced direct torque control and vector control technologies, performance of AC drives are
similar to DC drives in entire speed range. Usage of these advance speed control techniques in
AC drives gives excellent result to achieve desired torque- speed characteristics, dynamic response
and over load capabilities similar to DC drives. In February 2010, replacement of DC drive system
by AC drive system was carried out in hot rolled plate shearing line (PSL), which is cut to length
application line in steel plant. By various technical and financial comparisons, it is found to use of
AC drives more economical in comparison with DC drives. AC drives ensures, improvements on
energy efficiency, reliability and enhancement of production with reduction in cost, maintenance
and equipment down time. After replacement from DC drives to AC drives following performance
observed in PSL:
Energy saving of 1.88 kWh/t.
Production rate increased from 55 t/h to 95 t/h.
Line speed increased from 19.5 to 23 m/min.
Line stoppage time reduced from 2000 to 300 min./year.
Vol. 8, No. 4, December 2012
THE JOURNAL OF CPRI - Vol. 8, No. 4, December 2012
Recent Trends in Evaluation of DLMS Meters as per Indian Companion
Pradish M, Suresh V and Arunachalam V
The requirement of an Open Protocol for energy metering was a long awaited and most required
standard for bringing in homogeneity among various makes of meters deployed in the field by
the Power utilities. The openness of the standard will make the Automatic Meter Reading (AMR)
and interoperability into reality. This open protocol based on IEC-62056 (DLMS/COSEM) helps
to overcome most of the challenges for data acquisition for the utilities. The Indian Companion
Specification (ICS) was evolved by BIS as an Indian Standard IS-15959 which inherits the IEC62056 series of standards. This paper brings out the advantages of ICS and tests being performed
for compliance.
IEC61850 Standard and It’s Impact on Protection and Control Schemes within Power
Viral Joshi and Varsha A Shah
IEC61850 developed by International Electro-technical commission (IEC) is an approved
International standard for communication within the substation. It has introduced many new
features which can be used to build various applications for Protection of various equipments
within the substation. This paper there for focuses on various possible protections schemes based
on GOOSE messaging facility available in IEC61850 standard, its advantage/disadvantage over
Hardwire conventional protection scheme and cost effectiveness of implementing this new scheme
for an existing energy company.
Hybrid State Estimator with SCADA and Phasor Measurements
Jamuna K and Swarup K S
This paper investigates the problem of combining both the Supervisory Control And Data
Acquisition (SCADA) measurements and phasor measurements for state estimation. The SCADA
measurements are slow dynamic in nature than phasor measurements. The latency between those
measurements is compensated using Auto Regressive and Neural Networks. Weighted Least
Square estimator technique is used for estimating states of the power system. A Traditional State
Estimator (TSE) solution is obtained using SCADA measurements which already exist in energy
management system. The proposed work is performed on the TSE estimated states for future state
prediction. Future TSE state estimates are predicted at the instant of Phasor Measurement Unit
(PMU) measurements received at the energy management systems. Auto Regressive, Feed Forward
Neural Network and Nonlinear Auto Regression exogenous models are used for state prediction and
the effectiveness of these models are evaluated. Then, the state vectors of Hybrid State Estimation
(HSE) are calculated using predicted state vector and selected PMU measurements. The Neural
Network based SE provides best state estimates over AR based SE. The working of the proposed
process is validated through the simulations carried out on standard IEEE 14 bus, 30 bus, 57 bus
and 118 bus systems.
Vol. 8, No. 4, December 2012
Recent advances in HV and EHV Power Cable technology CPRI’s Experience in
Qualification Tests on Power Cables
Nageshwar Rao B, Meena K P, Thirumurthy and Raja G K
Over the years both due to demand and technological advancements there has been a continuous
transition from smaller operating voltages of 6.6. kV to higher voltages of 500 kV. The conventional
technology like taping or field moulding are in vogue and new technology like pre-moulded slip
on cable accessories are gaining importance for jointing of polymeric high voltage cables up to
voltages of 500 kV. The flammability characteristics of polymeric materials used in cable insulation
and jacketing have been of great importance over the years. Evaluation techniques have become
more stringent and both short term and long term tests are conducted in order to ensure the quality
of materials used, the manufacturing processes, workmanship and reliability. In this paper the
recent advances in HV and EHV power technology is summarized and the experiences in testing
and evaluation of 220 kV cables is presented and discussed.
A Multilevel Inverter Based Series Active Power Line Conditioner for Voltage Sag and
Swell Mitigation
Raihan Kagzi and Mulla M A
Series Active Power Line Conditioner (SAPLC) is a custom power device which protects the
sensitive loads against the voltage sags and swells. This paper presents three level diode clamped
inverter with DC storage capacitors along with three single phase transformers as a SAPLC.
Modified scalar control strategy with fast response time is used to improve the performance of
SAPLC. The simulation of the proposed model is carried out to verify the performance of SAPLC
in conditions of balanced sag, balanced swell and unbalanced sag. Results are analyzed to check
the effectiveness of the proposed model with selected control strategy.
Implementation of Shunt Active Power Filter Based on a Simple Novel Control
Vijay K Patel and Mulla M A
Shunt active power filter are commonly used as a harmonic and reactive power compensator. In
this paper, a simple control method is described to control shunt active power filter. It operates on
constant switching frequency, hence switching losses and stresses on the devices are lower. It can
compensate the reactive power required by the load without sensing and computing the associated
reactive power component, thus control circuit is made simple. It can also compensate harmonic
components of the non-linear loads. The experimental results are agreed with the analytical and
simulated results.
Wind-Fuel Cell Base Hybrid Energy System for On-Grid Electrification of Villages
Prashantkumar Pandya and Ranjit Roy
This paper introduces method for on-grid electrification of villages. A potential function for each
component like wind turbine, fuel cell, voltage regulator unit, control box, DC coupling device and
DC blocking device is used in this work. Secondary voltage control is achieved through voltage
regulator unit. The studies are simulated in time-domain continuous mode using MATLAB/Simulink.
Wind-fuel cell based hybrid energy system is tested with various wind speed. It is observed that
the proposed system is working satisfactorily.
Vol. 8, No. 4, December 2012
Fuzzy Controller Based STATCOM for Grid Connected Wind Generator
Muni Reddy G, Gowri Manohar T and Jyothsna Priya V
When integrated to the power system, large wind farms pose stability and control issues. A thorough
study is needed to identify the potential problems and to develop measures to mitigate them.
Although integration of high levels of wind power into an existing transmission system does not
require a major redesign, it necessitates additional control and compensating equipment to enable
recovery from severe system disturbances. In this paper, the STATCOM control scheme for the
grid connected wind energy generation system for power quality improvement is simulated using
MATLAB/SIMULINK in power systems block set. Fuzzy based controller is designed to improve
the source current in STATCOM. A marked reduction in the Total Harmonic Distortion is observed
in source current of Wind Power Generation System (WPGS) with the incorporation of Fuzzy
A Novel Approach to Harness Maximum Power from Solar PV Panel
Mrityunjaya Kappali and Uday Kumar R Y
Among alternate sources of electricity, Solar Photo Voltaic (PV) energy is gaining prominence due
to its plentiful availability. It is not being opted for in large numbers as grid parity of cost has not
been achieved. By harnessing more power per unit installed capacity of the solar panel, the cost can
be reduced. One of the methods of realizing this is by Maximum Power Point Tracking (MPPT)
wherein a power electronic converter is used to match the load with the PV panel. Widely employed
approach for MPPT is to monitor the power generated by the PV panel and keep on adjusting the
duty cycle of converter so that this power is always maximum.
Present paper proposes a novel method to realize MPPT for standalone solar PV system with
resistive (R) load. It is shown that the output power becomes the maximum when the load voltage
becomes the maximum. Conversely, varying the duty cycle of the converter such that load voltage
is always maximum leads to harnessing maximum power output. This approach can be referred to
as Maximum Load Voltage Point Tracking (MLVPT). Only one parameter i.e. load voltage needs
to be monitored. It is simpler than monitoring PV panel power as in that case it’s necessary to
measure both panel voltage and current and then find their product.
The proposal of MLVPT for realizing MPPT is substantiated by theoretical explanation. Simulation
as well as experimentation are also carried out. The results are found to be in close conformity
with the theoretical findings.
Vol. 8, No. 4, December 2012
10. Performance Evaluation and Financial Analysis of Solar Industrial Oven Using Pair
of Scheffler Reflectors
Ajay Chandak and Sunil Somani
To deal with climate change and fossil fuel depletion problems, direct utilization of solar energy is the
most promising option. Innovating new technologies and exploring possibilities to find new applications
for existing technologies is the key to resolve this problem. Scheffler solar concentrators based steam
generation systems are successfully deployed for community cooking applications in India. There
is need to look beyond cooking and develop different commercial and industrial applications using
Scheffler solar concentrator as a primary heat source. An Industrial Oven is developed by authors
for catering mid temperature applications in Industries, which utilizes Scheffler solar concentrator of
16 m2 as a prime source and two such concentrators focus inside a single oven. This innovation
delivers 9 kW, which is good enough heat for many industrial applications in 100°C–200°C range,
replacing electricity or fossil fuels like LPG or diesel. The trials show excellent technical and
financial viability of the new design. Depending on fuel to be replaced, payback period varies from
2–6 years. Paper discusses development process of the new product and financial analysis for the
11. Optimization of Annual Energy Generation in run of the River of Hydro Power
Siddhartha Bhatt M and Jothibasu S
Annual variation in water inflow down to 50 % of its maximum value is quite common in run
of the river hydro plants (with storage of 1–3 hours of power generation capacity) with multiple
stations located on the same river in intervals of 30–50 km. The low capacity factors (< 40 %) call
for efficient water management for modulation of unit and station loads to co-ordinate operations
and maximize energy generation. The efficiency characteristics (which represent the utilization
efficiency of water resources)of the hydro units are not flat but decrease with decrease in load. The
net operating efficiencies of individual hydro power plant units decrease sharply at lower loading
levels below 80 % of the rated capacity due to swirling and vorticity components on one hand and
erosion-cavitation on the other hand. The parameter (Pmin/Pmax) amongindividual units influences
the net overall efficiency to the tune of 2–10 % points in multi-turbine, multi-station environments
of a river. By optimal selection of the loads to maximize this parameter, the energy generation
can be maximized. The ultimate solution to optimal water utilization is to achieve a flat efficiency
curve over the load range through 3-d designs of turbine runner. Silt control also plays a role in
the energy efficiency but is controllable and secondary.
Vol. 8, No. 4, December 2012
12. Thermal Management of LEDs for Lighting Solution
Ingole Sunil B and Sundaram K K
Lighting is rapidly transitioning from conventional lamp resource such as high-pressure sodium,
metal halide, mercury vapor, and fluorescent to high brightness light-emitting diodes. Standard
incandescent lamp have luminous efficacy as 16 lm/W, whereas LEDs are expected to be 90 to 140
lm/W, with the life of LEDs to be 50,000 hrs. As efficiency and drive current increase, the total
lumens per emitter increases, reducing the initial cost of light and by providing energy savings.
In LED lighting about 30% energy is distorted in light, whereas 70% is parting as heat. The
junction to ambient resistance can be varied by using active cooling systems. Also the term used is
Enhancement Factor (EF) of the active cooling devices. Enormous scope is observed in deviation
of material and their combinations for effective thermal investigation. Variety of active and passive
heat removal techniques are reported and hybrid systems are evolving. A range of aspects of thermal
management, its need and scope is presented in view of developing LED lighting solutions for
general household and corporation applications, which will be of great help for saving nation’s
wealth, by saving power utilization in lighting the country.
13. Study on Estimation of Lifetime of Transformer Oil in Service
Maiti P K
Lifetime of a transformer depends on the age of its electrical components, liquid and solid insulation.
So study on ageing of oil is equally important as that of the solid insulation. The oil under service
is subjected to thermal and electrical stress. Presence of oxygen and moisture and contaminants
act as catalyst to accelerate the ageing process. Oil is regularly monitored to assess the extent of
ageing. It is also desirable to establish the remaining life of the oil at various point of time during its
service period. In order to do that it is required know the rate of degradation of oil under operating
conditions. It is well known that the operating conditions vary from one transformer to other and
which is further influenced by the environmental factors. Due to these facts, the ageing of oil is
considered to be a complex process. This suggests that the study to be conducted on large number
of transformers in order to get a representative ageing characteristics. In the present study, a large
number of oil samples drawn from power transformers of various age groups were analyzed. It is
observed that deterioration of Interfacial tension and acidity is almost linear with service period
and can find application in assessing lifetime of the oil.
Vol. 8, No. 4, December 2012
14. Basics of Dissolved Gas analysis and Case studies for Power Transformers
Dipak Mehta and Hitesh Jariwala
Electrical insulating oils of petroleum origin are extensively used in transformers. The physical,
electrical and chemical properties of such oils are subject to change due to environment and electrical
stresses. For use in any electrical apparatus the oil has to comply with certain requirements and
determination of these properties before filling the apparatus is of utmost importance. It is also
equally important to monitor the condition of oil in service. Condition Monitoring of Insulating
oil of power transformer is performed by oil contamination and dissolved gas analysis. In Oil
contamination test comprise of breakdown voltage, water content, neutralization value, sediment
& sludge, resistivity, dielectric dissipation factor, interfacial tension and flash point. DGA analysis
is obtained by IEC ratio method, Rogers ratio method, Key gas method and Dual triangle method
to distinguish the possible fault types by analyzing the amount of gases dissolved in the insulating
oil. Total 108 no’s transformer tested for oil contamination test and dissolved gas analysis. Out of
them 3 no’s case study chosen for analyzing Insulating oil condition. Also other 2 no’s case study
is chosen from Different industries for analysis purpose.
15. Studies on the Effect of Additive Package in Enhancing the Lubricant Properties of
Gear Oil
Muralidhara P L, Kavyashree M J, Gowrishankar B S, Jagannadha Rao Y and
Jayarama Naidu C
The aim of this research study is to study the effect of gear oil additive package with base oil. The
formulation of this type of lubricant is based on gear oil additive package with stable base oil. The
study evaluates the laboratory testing results for oils obtained from mixture of base oil and gear oil
additive package and the optimization of additive package to the base oil for better performance
when compared to commercially available gear oil in market. The values of the properties of the
additive blended with base oil depend on the characteristic of mineral base oil and the concentration
of the additive package.
16. Physico-Chemical Studies on the Effect of Package Additives in Automotive Engine
Muralidhara P L, Guruprasad M, Nirguna Babu P, Jagannadha Rao Y
and Jayarama Naidu C
Lubricating oils are extremely essential for the operation of modern automotive machinery. They
are formulated by blending special purpose chemicals into Base oil of crude origin to achieve
desired properties required by application at hand. In the present work, commercial package additive
(multi-chemical compound) has been used to formulate the Engine Oil. The blending proportion
of package Additives are varied from 0–15 volume % and its tribological properties are measured
using standard test methods. The Physico-chemical studies on the effect of addition of package
additives to formulate automotive engine oil are studied and reported.
Vol. 8, No. 4, December 2012
17. Transformer Fault Analysis Using Finite Element Method and Frequency Response
Pritesh Bhoniya and Prasanta Kundu
With the appearance of deregulation, distribution transformer predictive maintenance is becoming
more important for utilities to prevent forced outages with the consequential costs. To detect and
diagnose a transformer internal fault requires a transformer model to simulate these faults This
Paper presents here an approach has been shown for transformer fault analysis. A transformer
model was designed for a 10 MVA, 132/66 kV three phase system. Data for all the parameters
essential for designing a transformer were calculated, after studying machine designing. The next
task was to calculate the inductance and capacitance (lumped values) which is later on used to
make the ladder network which represents the transformer as inductance capacitance model. After
dividing the total inductance and capacitance into segments the ladder network is ready to be used
for short circuit fault analysis. Artificial faults were created by shorting a few segments at a time
and the output voltage corresponding to input voltage under different faulty conditions were noted
down. These values were used to create a frequency response curve which was compared with the
response under normal condition and further analysis was done.
18. Investigations to Identify SFRA Measurement Sensitivity for Detecting Faults in
Pritesh Bhoniya and Prasanta Kundu
A common failure mode for power transformers is consequent to mechanical deformation of
the core or windings. Core damage is more likely as a result of transportation, while winding
damage is more likely to be caused by short circuit type forces. Sweep Frequency Response
Analysis (SFRA) is an effective low-voltage, off-line diagnostic tool used for finding out any
possible winding displacement or mechanical deterioration inside the Transformer, due to large
electromechanical forces occurring from the fault currents or due to Transformer transportation
and relocation. This paper describe through case studies that SFRA test is more sensitive to detect
faults compare to conventional testing method.
19. Thermography – A present Trend of Condition Monitoring for Electrical
Equipments in Petroleum Industries – Research Data
Prashantkumar Koradia and Prashantkumar Pandya
Thermography (thermal imaging) has evolved into one of the most valuable diagnostic tools for
predictive maintenance. By detecting abnormalities often invisible to the naked eye, thermography
allows corrective action to be taken before costly system failures occur. The paper introduces the
method of condition monitoring of running equipment using thermography followed in refinery for
last 4 years and the results obtained considering the same. The failure and breakdown were predicted
before the occurrence of the same. The occurrences has been lower down from 3.21%–0.25% to
total installed equipment per year while the failure rate reduced from 0.29%–0.02% per year.
Vol. 8, No. 4, December 2012
20. Six Sigma Analysis of Electrical Motors in Refineries Combining Criticality Index
and Condition Monitoring of Motors using Vibration Analysis
Prashantkumar Koradia and Bhusavalwala M N
To achieve the goals of management for six sigma level breakdowns, zero accidents, and zero
effect on quality of product along with least maintenance cost, the concept of RCM had helped
engineers a lot. The primary need for RCM is deciding criticality index number and CM and PM
frequency are decided thereafter based on criticality score ensuring the coverage of all the critical
equipment. As CM and PM of all equipment is time consuming, more concentration should be
given to equipment with higher criticality. Electric motors have seen to be widespread adoption in
every application and their condition monitoring has received considerable attention in recent years.
Motor’s abnormal vibration signals include its fault information and these vibration signal analysis
is used to monitor motors to predict and prevent major problems. Condition monitoring using
vibration analysis has achieved meaningful results in successfully diagnosing motors problems.
This paper introduces a way for risk assessment approach to decide criticality index of equipment
in petroleum refinery and combining the same with CM technique like vibration analysis for motors
in petroleum refinery for achieving zero breakdowns in motors with the results derived from the
past 3 years.
21. Power Factor Improvement in the Steel Plant with Advanced AC Drive System
Shah S, Panchal A K and Varsha A Shah
This paper presents the analysis of power factor with DC drive system and AC drive system in
one of the major steel plant in India. Replacement of DC drive system with AC drive system
have drastically improved power factor of the system. With advanced direct torque control (DTC),
performances of AC drives are similar to DC drives in entire speed-torque region. By various
comparisons of technical and financial parameters, it is found economical to use AC drives in place
of DC drives. AC drives ensure improvements on power factor, energy efficiency, reliability and
production with reduction in cost, maintenance and equipment down time.
After comparing the DC drive system and AC drive system in pickling plant, the power factor
improvement observed with AC drive system. The simulation studies also predicted that there
will be improvement in average power factor from 0.2~0.65 to 0.93~0.97. Results obtained after
replacement of DC drives with AC drives are quite matching with the predicted results. In addition,
AC drive system also helped in energy saving and reduction in line stoppage occurrences.
Vol. 9, No. 1, March 2013
THE JOURNAL OF CPRI - Vol. 9, No. 1, March 2013
Dynamic Compensation Studies using RTDS for Large Wind Farm Integration with
Meera K S and Shivakumara Aradhya R S
Amongst all renewable energy sources so far identified in India for commercial exploitation,
wind energy is the one, which has been found to be more viable for generation of grid quality
power. Following recent growth of wind generation, utilities have responded by developing various
interconnection requirements/guidelines to which the wind farm must abide. The guidelines provide
for penalty to be levied by State Electricity Boards, if the projects fail to achieve minimum monthly
average power factor of specified value at the coupling point. Suitable penalties are also levied for
reactive power to discourage drawl of reactive power from the grid and to avoid free wheeling of
the machine.
Majority of wind generator topologies are asynchronous machines, which draws reactive
power from the grid. Thus, there is a requirement that the wind farms be self sufficient with respect
to the needs of reactive power of the wind farm. The methods of reactive power control may be
provided in the form of capacitor banks, static power converter based devices (SVC, TSC, or
STATCOM) or by employing machines capable of reactive power control, such as the doubly-fed
induction machine topology.
This paper discusses the results of grid integration studies of wind farms, based on three
phase dynamic simulation utilizing the real time digital simulator (RTDS). It investigates the
application of STATCOM for a typical wind farm for providing an effective means in dynamic
voltage control of the wind farm, meet the reactive power requirements of the wind farm and
enhance the capability of the wind farm to ride through the grid disturbances.
Reliable Control Strategy related to Hybrid Eenergy System for On-Grid Electrification
of Villages in Weak-Grid Environment
Prashant Pandya and Ranjit Roy
Method for on-grid electrification of villages. An improved control strategy is incorporated which
enable the system to switch on in to grid and whenever required it can be set back to a micro grid.
The studies are simulated in time-domain discrete mode using MATLABTM/SimulinkTM. Wind-fuel
cell based hybrid energy system is tested with all possible control parameters and it is observed
that the proposed control strategy is working satisfactorily.
Vol. 9, No. 1, March 2013
Distributed Generation and its Impact on Power System
Grishma Patel
The penetration of distributed generation (DG) into the main electricity network is changing the
paradigm we used to live with. DG is gaining interest worldwide as numerous benefits are associated
with this change due to penetration of DG. In this paper the main purpose is to show the basics
of distributed generation. The different ways to interface the DG with the utility system are also
reported. Penetration of a DG into an existing distribution system has many impacts on the system
and equipment operations in terms of steady-state operation, dynamic operation, reliability, power
quality, stability and safety for both customers and electricity suppliers. However here in this paper
the more focus in on impact of DG on power quality pointing out its positive and negative impacts
and its solutions. At last to support this arguments analysis of results are shown which are directly
taken from the references, where the results revels the effect of DG on power quality and based on
that some conclusions are documented.
Swarm Intelligence based Distribution Load Flow Method for Distributed Generation
Naveen Jain, Singh S N and Srivastava S C
This paper presents a new swarm intelligence method of distribution load flow (DLF) suitable
for systems with distributed generators. The proposed DLF method is able to incorporate all kind
of voltage dependent load models. This load flow method avoids the problems faced by various
methods in handling multiple PV buses and is also suitable for small-scale, medium-scale and largescale distribution systems. The proposed DLF method is used for placing multiple fixed standard
size capacitors. The optimal sitting and sizing of multiple DGs are also carried out utilizing a
system loss reduction criterion. The proposed load flow algorithm is tested on distribution systems
with fixed standard size capacitor and/or DG for various load models to show its effectiveness.
Some existing DG planning results are compared to show the capability and the accuracy of the
proposed algorithm.
A Review on Effective Lightning Protection for Wind Turbine Generators
Ashok Kumar L
A wind turbine generator is the most exposed of all types of generators connected to electric utility
systems. Wind turbines are most often erected in hostile lightning environments. Lightning damage
to wind turbines is costly in terms of repair and replacement of equipment. Lightning damage is the
single largest cause of unplanned downtime in wind turbines, and that downtime is responsible for
the loss of countless megawatts of power generation. There is currently no international standard
governing wind turbine lightning protection. This paper is a review on the available guidelines for
effective protection.
Vol. 9, No. 1, March 2013
Computed Lightning Electric Field Ratios of First and Subsequent Return Strokes
Chandrasekaran K and Gururaj S Punekar
Electromagnetic fields generated due to ‘typical’ first return stroke (FS) and subsequent lightning
return stroke (SS) have been computed and compared. The simulation results are discussed keeping
in view the field data reported in several recent literature, which compares the severity of first and
subsequent return strokes. The MTLE based engineering model is adopted to compare the severity
of lightning return strokes (FS/SS) as a function of radial distance and the worst case ground
In general, the magnitude of electric field peak due to of first return stroke is nearly twice
that of field peak due to subsequent return stroke as reported in the literature, based on the data
collected by lightning detection, information and field measurement systems. The present simulation
results not only substantiate this fact but also try and assess few parameters responsible for low
ratio of FS/SS (reported in some cases) through simulation process; as causes for these low ratios
are yet to find satisfactory explanation.
Swarm Intelligence based Approach for the Loss Minimum and Cost Minimum
Configuration of an Interconnected Power System
Vikash Kumar Gupta, Bhattacharyya B and Goswami S K
This paper presents particle swarm optimization (PSO) based approach for the allocation and
coordinated operation of multiple FACTS (Flexible AC Transmission System) devices for the
economic operation as well as to increase power transfer capacity of an interconnected power
system under different loading condition. The PSO based approach is applied on IEEE 30-bus
system. The system is reactively loaded starting from base to 200 % of base load. FACTS devices
are installed in the different locations of the power system and system performance is noticed
with and without FACTS devices. First, the locations, where the FACTS devices to be placed is
determined by calculating active and reactive power flows in the lines. A PSO based algorithm is
then applied to find the amount of magnitudes of the FACTS devices. This PSO based approach
for the placement of FACTS devices yields promising result both in terms of performance and
economy which is clearly observed from the results obtained.
ANN Based Adaptive Relaying Scheme for Protection of Active Distribution
Raghavendra G, Nagaraja R and Khincha H P
This paper presents a new adaptive relaying scheme for the protection of active distribution networks,
i.e. protection of distribution networks connected with distributed generation/dispersed generation
(DG). The traditionally radial distribution systems may no longer be radial in the presence of DGs,
which can hinder the existing co-ordination between the protective relays. This paper addresses
the relay co-ordination issues encountered due to the presence of DGs in the network and explores
the application of Artificial Neural Networks (ANNs) as a solution for the protection of active
distribution networks. The proposed method, based on ANN, shows that the issues regarding relay
co-ordination can be overcome and only the faulted section can be isolated precisely.
Vol. 9, No. 1, March 2013
Supervised Tripping and Blocking of Distance Relays
Raghavendra G, Faraz Z Khan, Nagaraja R and Khincha H P
This paper introduces a new scheme for supervised tripping and blocking of distance relays using
the data from phasor measurement units (PMUs). The proposed scheme utilizes fault detection,
double ended fault location algorithm and expert system rule sets to arrive at a decision whether
to trip or block the backup protection. Conventional distance relays encounter challenges in the
form of parallel line operation, mutual coupling effect, fault resistance etc. These issues are well
addressed by the proposed scheme in a reliable manner and the concept is supported by the case
10. Sub-synchronous Resonance through Torsional Mode Interactions: An Analysis
Shashidhara M Kotian, Sreenadh Batchu and Shubhanga K N
Interaction between electrical and mechanical systems, generally termed as sub-synchronous
resonance (SSR) in power system, is not a straightforward problem to analyze as it involves
detailed modeling of both systems. From the literature it is found that in most of the cases the SSR
analysis is demonstrated through the IEEE first-benchmark system which contains many intricate
modal interactions. To motivate the students to take up such standard systems for analysis, in
this paper an example is presented which brings out the issues associated with the analysis by
employing simplified models for generator and mechanical systems. Model and design equations
are systematically derived so that any variations can be tried with ease. Case studies are presented
to demonstrate the concept of modal interactions by studying the systems both in isolation and in
combination. Eigenvalue analysis is carried out in addition to time-domain simulation to show that
SSR is purely a discrete event.
11. Effective Location of SVC Controller for Small Signal Stability Enhancement in Multi
Machine Power Systems
Senthil Kumar N
The problem of small signal stability is usually due to insufficient damping of system oscillations.
The power electronic based FACTS devices are effective for system voltage control and power
flow control. This paper presents a systematic method of developing the small signal model for
stability enhancement in a power system using SVC. While the primary purpose of a Static Var
Compensator (SVC) is to regulate bus voltage, it can also improve stability and damping of a power
system if located appropriately. This paper proposes a Residue factor to find the location of SVC in
multi-machine system. The proposed residue factor was based on the relative participation of the
parameters of SVC controller to the critical oscillatory mode. The algorithmic steps for computing
the residue factor is proposed, which combined the linearized differential algebraic equation (DAE)
model of the power system and the SVC output equations. The effectiveness of the proposed
method was demonstrated on the standard WSCC 3 Machine 9-Bus system. All computations were
carried out using MATLABTM v7.6.
Vol. 9, No. 1, March 2013
12. Control of Harmonics Generated by Alternating Current Electric Arc Furance and
Laddle Furnace
Rajashekar P Mandi, Janak J Patel, Hitesh R Jariwala and Ankur Vashi
An arc of an electric arc furnace as a virtual short circuit is purely resistive load but the reactor
connected in series with primary of furnace transformer to smoothen the arc makes the total
combination as an inductive load, with its fluctuating active and reactive power requirements,
it leads to power quality issues such as poor power factor, harmonic generation, etc. This paper
presents measurement and analysis of harmonics generated by alternate current electric arc furnace
(AC EAF) and laddle furnace (LF) loads and also defines terms like harmonics, total harmonic
distortion etc. Harmonic Filter Banks (HFB) of static Var compensator (SVC) are tuned to particular
order of frequency to provide least resistance path to that order of harmonics for elimination. This
paper also describes design criteria for harmonic filter banks of 100 Hz, 150 Hz and 200 Hz and
presents the SVC as a solution for control of harmonics. The final results are compared with
allowable limits set by international standards.
13. Comparison of Alternate Current Electric Arc Furnace with Direct Current Electric
Arc Furnace with their Static Var Compensator configurations
Rajashekar P Mandi, Janak J Patel, Hitesh R Jariwala and Ankur Vashi
An electric arc is purely resistive load, but the series connected reactor to smoothen the arc makes
the combination inductive load creating power quality issues like harmonic generation, poor power
factor, voltage flickers etc. An electric arc furnace is heart of integrated steel plant used for smelting
of steel with help of electric arc. Temperatures insider the furnace can reach up to 1800° centigrade
and capacity wise electric arc furnaces are available from 1–300 tonnes. The charged material
is directly exposed to the electric arc and results into hot liquid steel. The charged material can
be steel scrap, direct reduced iron and hot metal. The electric arc furnace can be classified as
alternate current electric arc furnace (AC EAF) and direct current electric arc furnace (DC EAF)
depending upon source of power used at furnace for arcing. The objective of this review is to
compare the configuration and harmonics generated by operation of AC EAF and DC EAF. Static
Var compensator (SVC) is solution to mitigate the power quality issues generated by the electric arc
furnace. This review also compares configurations of the SVCs used for AC EAF and DC EAF.
14. Reactive Power Management Practices and their Comprehensive Evaluation for a
Short Circuit Test Plant
Venkateswarlu G, Mondal N R, Ansari M A and Raghavaiah B V
A vast majority of electrical loads in short circuit testing plants are inductive rapidly varying
in nature. Typical examples are motors, transformers, drives etc. Such loads consume high
reactive power in short durations. Load requirement of the short circuit plant is intermittent in
nature due to varieties of customer tests. Hence controlling of reactive power of these types
of loads is a challenge. It is therefore necessary to reduce and manage the flow of reactive
power to achieve higher efficiency of the short circuit plant and reduction in cost of electricity
consumed. An improvement of the reactive power management of an installation presents several
technical and economic advantages, notably in the reduction of electricity charges. This paper
discusses a cost effective method of reducing and managing reactive power. It has been shown
that the installed reactive power compensating devices captured both the technical and economic
aspects of short circuit plant operation in competitive electricity markets. Also it has been shown
that traditional techniques are economically viable if they are used in a judicious manner.
Vol. 9, No. 1, March 2013
15. Five-Limbed Transformer Cores
Sankar V
There are many five limbed core configurations. In all the existing configurations specific loss
(loss per kg at a given flux density) is higher than the three phase three legged core. The reasons
are yoke areas not matching with the amount of the flux flowing and the mitered joints also not
matching with the quantity of the flux flowing. Compared to the non-split cores, the split cores
are posing manufacturing problems and higher losses. Model core of a new configuration and
two model cores of existing configurations were built and tested. Relative merits of the new core
configuration and reduction in losses are tabulated. This new core configuration can be adopted
easily for both non-split and split cores. Relative advantages and disadvantages of different core
configurations are discussed.
Tests conducted on model cores described in this paper are limited to five-limbed core type
transformer cores. Iron losses were measured at different flux densities on model five-limbed cores
with different core configurations. The first model (Type 1) is the typical configuration being used
by transformer manufacturers around the world. An attempt is made to build another model fivelimbed core (Type 2) by modifying the position of mitered joints of main end limbs laminations.
This modification was done so that the flux from the main end limbs can flow from limbs to yokes
without overcrowding at mitered joints. Often, the diameter of the main limbs is greater than the
maximum widest width lamination normally available (1000 mm). For this reason, five-limbed
cores often have split limbs. A third model (Type 3) representing the split core was also built to
get a loss comparison with non-split cores.
16. Finite Element Analysis of Transformer Clamping Structure to Study Effect of Copper
Shield on Structural Losses and Winding Eddy Losses
Ram Krishna Mishra and Saravanan Selvaraj
The losses due to transformer leakage field comprise a small percentage of the power in a transformer.
Yet these losses produce localized heating which can compromise its operation. The stray field
strength increases rapidly with growing rating. The stray flux intruding into the structural parts
gives rise to eddy currents in them. The resulting eddy current losses may be considerable, thereby
increasing the load loss of transformer [1, 5]. The objective of this work is to calculate stray losses
in magnetic structures of 400 MVA 1-phase, 500–230 kV auto transformer and study the effect of
copper shield on structural losses and winding eddy losses, using commercial software package
Magnet (Infolytica Corp.) based on finite element method (FEM). Due to presence of non linear
magnetic materials, the sinusoidal source with 60 Hz frequency induces non-sinusoidally varying
magnetic fields. A transient solution (which calculates time varying magnetic field) is required for
calculating fields in non-linear materials. However, this requires more computational resources.
Therefore Time harmonic solution (which calculates field at 60 Hz frequency) with linear magnetic
materials is used for this analyses. Further, 3D time harmonic analysis has been done to analyze the
effect of varying Cu shield thickness on loss density and finally its effect on winding eddy losses
has been investigated.
Vol. 9, No. 1, March 2013
17. Prominence of Magnetic Properties in Grain Oriented and Non-Grain Oriented Steels
for Transformer Industry
Arjuna Rao S, Swaraj Kumar Das and Raghavaiah B V
Cold rolled grain oriented (CRGO) electrical steel is a critical raw material for manufacturing of
transformers, which is fully imported as it is not manufactured in India. Currently India consumes
about 2.5 lakh metric tonne per annum of CRGO electrical steel and with the growth in demand
of transformation capacity the consumption is estimated to be 11.5 lakh metric tonne and 13.5
lakh metric tonne respectively during the 12th and 13th five-year plan period. Magnetic cores for
the wide range of modern electrical and electronic devices require magnetic materials with many
combinations of properties and characteristics. The evaluation of magnetic core materials is very
crucial before using for transformers, motors and Inductors.
18. Quantitative Analysis Ageing Status of Insulation of High Voltage Motors by
Polarization – Depolarization Current Measurements
Tapan M Rami and Dipak Mehta
Polarization and depolarization current (PDC) technique is an effective tool to assess the condition
of insulation system in high voltage motors So far the PDC behaviors of insulation have been
widely investigated. This Paper presents the assessment of insulation systems for high voltage
induction motor through measurement of polarization depolarization current or charging and
discharging current. However, with the increasing number of Motors choosing insulation , it is
important to investigate the PDC characteristics of insulation to see whether the PDC technique
can also be used to assess the condition of new insulation system using PDC accurately It is
considered that the insulation systems are having different types and conditions of insulation
aging. It demonstrates that the insulation resistance (IR) and polarization index (PI) can’t be used
individually to judge insulation dryness and the combination of insulation resistance and PI. PDC
analysis is better technique of insulation quality assessment than the insulation resistance alone.
The PDC analysis is non destructive dielectric testing method for determining the conductivity and
moisture content of insulation materials in high voltage motors. On the basis of this analysis, it is
possible to take further actions like overhauling, drying process, and replacement of the winding of
the motor. This paper also presents a description of PDC analysis technique with the practically and
theoretical background and some results of PDC measurements on High voltage motor duration from
0–600 days.
Vol. 9, No. 1, March 2013
19. A Study on Integration of Acetone Charged Copper Pipes (ACCP) to MR16 Indoor
Lighting Solutions
Gopalakrishna K, Krishna Venkatesh, Rama Narasimha K, Ananda M A, Parasuram A K,
Gururaja G, Jayaprakash P N and Sendil Kumar T J
The aim of the present study is to improve the thermal performance of the MR16, 7 W and 9 W
LED decorative lighting solutions by integration of acetone charged copper pipe (ACCP) into
its aluminum heat sink. With integration of ACCP, the luminary designed for lower wattage can
withstand higher wattage and can accommodate more LED’s with increased illumination. The
heat transfer characteristics of high power LED is analyzed and a novel ACCP cooling device for
high power LED is designed. The thermal capabilities of lighting solutions with integration of
ACCP and without integration of ACCP for the same load (fixture + heat sink) were investigated
experimentally. The experimental results indicate that the given load can accommodate more LED’s
for higher wattage which can be attributed to improved heat transfer after integration of ACCPs
resulting in increased illumination.
20. Investigation of Mechanical Properties and wear behavior of Ni-alloyed Specially
Heat Treated Permanent Moulded Austempered Ductile Iron (PMADI) for Power
Plant Applications
Sethuram D and Narasimha Murthy K
Austempered ductile iron (ADI) is relatively newer material, which has attracted researchers and
manufacturers alike mainly because of its immense properties and also at the same time cheaper
to process and produce. Utilization of permanent moulds to ADI has many advantages such as
very good dimensional stability, good nodule size count, better surface finish and environmental
cleanness. Extensive literature survey reported that ADI out-performs proprietary abrasion resistant
steels at similar bulk hardness levels.
Experiments were systematically planned to study the mechanical and wear properties of Ni-alloyed
PMADI and are processed by a novel two step austempering process. All specimens were initially
austenitized at 950 °C for 2 h. These samples were initially quenched for 5 min in a salt bath
maintained at 250° C and then austempered for 2 h at several austempering temperatures. These
temperatures were 280° C, 310° C, 340° C, 370° C, 400° C, and 430° C. The results show that this
novel process has resulted in higher tensile strength, yield strength, hardness and wear resistance
than the conventional single step austempering process. The tensile strength value improved by
about 11% for 2% Ni PMADI samples over 1.5% i PMADI samples while maintaining reasonable
levels of ductility. The results are analyzed based on the micro structural features.
Vol. 9, No. 1, March 2013
21. Corrosion Behaviour of Aluminium Alloy-Flyash Composites used in ESP
Suresh N, Venkateswaran S, Seetharamu S, Sampath Kumaran, Ramachandran B E and
Praveen Kumar T N
The effect of corrosion on aluminium alloy (LM6) containing ceramic fly ash based microspheres is
investigated in this work. Stir casting route has been employed to disperse 10 % ceramic microspheres
as reinforcement in the alloy matrix. Further, the alloy system was subjected to grain refinement,
modification as well as combined action of grain refinement and modification. Three sets of LM6
alloy castings were produced in each case, to check for reproducibility. The corrosion resistance
was evaluated by immersing the samples in 3% NaCl solution. The pH and electrical conductivity
were measured to assess the damage due to corrosion. It was observed that the corrosion resistance
decreased in the composite samples subjected to grain refinement, modification, combined action
of grain refinement and modification compared to untreated alloy composite. Scanning Electron
Microscopy [SEM] has been used to substantiate the corrosion data. On the other hand, mechanical
properties namely hardness and ultimate tensile strength improved greatly in the modified samples
compared to grain refined and grain refined and modified samples.
Vol. 9, No. 2, June 2013
THE JOURNAL OF CPRI - Vol. 9, No. 2, June 2013
1. Investigation on Flashover Performance of 25 kV Traction System Section Insulator Assembly in DMRCL System
Dharmesh Y, Vasudev N, Karunakara K, Sheshagiri Rao U R, Shivakumara Aradhya R S, Anoop
Kumar Gupta and Mukesh Wadhwa
This paper describes the failure analysis of a section insulator assembly at one of the depot of Delhi
Metro Rail Corporation Limited (DMRCL). Frequent breaker tripping at Saritavihar depot of DMRCL
due to flashover of the section insulator assembly was observed; the cause of failure of the section
insulator was investigated and presented in this paper. As a first step laboratory tests on new and
used section insulator assemblies were conducted to make comparative analysis, and then simulation
studies were carried out to estimate the possible over voltages during different switching operations
and their relationship with the test voltages used in the experimental investigation. This paper presents
the laboratory experiments and simulation studies for the failure analysis of section insulator assembly
Types of Power Quality Disturbances on AC Electric Traction Drives: A Survey
Mohan Krishna S
Modern electric traction drive systems make use of power electronic devices which directly affect
its performance and efficiency. Numerous power quality phenomena are associated namely: Voltage
flicker, Harmonic voltage and current distortion, voltage dip, transient over voltages, voltage and current
unbalances. It is important to emphasize the fact that all the above mentioned phenomena appear due to
the non linearity of the loads, who by themselves act as harmonic current generators. This paper gives
a brief overview of the power quality disturbances which cause significant impact on the traction drive
system as well as the supply side.
Vol. 9, No. 2, June 2013
Significance of Support Structure for Short Circuit withstand Strength of
Bus-bar Assembly Panels - Experiences with Testing
Maheswara Rao N, Girija G, Vasudevamurthy B R and Swaraj Kumar Das
This paper describes short circuit withstand capability of Bus-bar assembly panels and the significance
of Bus-bar support structures commercially available in use. Recent developments in Bus-bar support
structures for assembly panels are also discussed. The performance comparisons of these support
structures under the Short-circuit currents were given. Few failure cases are studied from the laboratory
tested panels and appropriate recommendations were proposed. This can give an insight, while selecting
the suitable bus-bars support structure. Theoretical Force calculations were compared for different Busbar geometrical configurations.
Identification of Dynamic Characteristics of 12 kV Circuit Breaker under Earthquake Loading
Srujana N, Ramesh Babu R and Katta Venkataramana
History of past earthquakes had demonstrated that structural failures in substations were non- recoverable
unless huge amount of money and man power involves in it. A broad range of substation equipment
are especially vulnerable to seismic vibrations and circuit breaker is one among them. Failure in circuit
breaker results flow of excessive current in substation components than the respective ratings. Excessive
current in substation components cause fire accidents along with power outages. The efficient way to
resolve the problem is to analyze and identify the failure points over the earthquake vibrations before
installing in the field. This paper discusses in relation to earthquake acceleration amplification of 12 kV
circuit breaker used in substations. Shake table experiments are conducted on circuit breaker at higher
seismic zone levels. The ground motion amplification obtained from finite element analysis and shake
table tests is compared.
Design of A New Deregulated Market Structure for an Indian Grid with Focus on Different Controllers
Peer Fathima A, Shrinivass A V and Shravanthi R
The main objective of this paper is to create a new deregulated market structure namely Dyadic Market
Structure which provides an optimal environment to nurture private sectors and also to protect customer
interests. The four area interconnected system (Andhra Pradesh, Karnataka, Kerala and Tamil Nadu)
of the Southern Regional Grid is considered as a public sector of this structure and its frequency
response is improved by secondary regulation by using various controllers like PI, PID and Fuzzy logic
Controllers. The simulation is carried out using MATLAB SIMULINK.
Vol. 9, No. 2, June 2013
Improvements in the Development of Grid Code and Review of Power Quality Requirements for Fluctuating Wind Power Generation in India
Amuthan N and Subburaj P
This paper deals with the improvements in the Indian grid code and the important point in the power
quality requirements. It reviews the Indian grid code and the grid code requirements for wind energy
conversion systems and the modifications in the Indian wind energy grid code is presented for further
improvements. Power quality issues and requirements in the grid integrations are briefly explained.
The main objective of the power quality review is to study the basics of power quality, standards,
measurements and the devices used to improve the power quality. The current The International Electrical
Commission (IEC) standards were described and the measurements standards are presented. The power
quality problems associated with grid integration like voltage fluctuations or flicker; harmonics and
interharmonics; voltage drops; active power; reactive power; grid protection and reconnection time
are studied and the implementation of the measurement and assessment procedures, specified by the
various standards are discussed.
Low Voltage Ride Through Capability Analysis of DFIG using Feed Forward Current Regulator
Bankar D S and Talange D B
In recent years due to increase in the load demand a lot of emphasis is given on the use of nonconventional energy sources since fossil and atomic fuels will not last forever, and that their use
contributes to environmental pollution [1]. Out of all non-conventional energy sources wind has been
the fastest growing energy source over the last decade mainly due to very significant improvements
in wind energy technology. Doubly fed induction generators have become the most popular type of
wind turbine generators due to its excellent characteristics of control. But, these types of generators
are susceptible to grid-side low voltage faults and short circuits. Power electronics converter connected
on the rotor side affects badly under these conditions. When a short circuit or voltage sag occurs on
the grid side, the rotor current of the generator tends to rise, which could cause damage to the rotor
convert. To overcome this difficulty RSC is disconnected and crow bar is activated thus the DFIG now
acts as the conventional induction machine. Grid codes suggest that these plants are required to remain
connected to the grid in the event of voltage dip also they should contribute to the power system by
feeding the active and reactive power safely [5]. The LVRT requirement is very important as far as
grid stability is concern when a large wind farm is connected to the grid. But it is difficult to satisfy
for wind plants using DFIG system since the DFIG stator is directly connected to the grid and the rotor
is connected through RSC, hence complete DFIG system is much sensitive to grid disturbances [4].
This paper presents the feed forward current regulator for rotor side converter of DFIG and analyses its
low voltage ride through capability. The results show that the LVRT capability of doubly fed induction
generator has improved.
Vol. 9, No. 2, June 2013
The Electrical Vehicle to Grid, it’s likely Impact on Future of Power System – A Review Paper
Sudhir Kumar R, Deshpande R A and Kavitha D
Vehicles running on oil have to change over in next few decades to alternatives which could be hydrogen,
electricity. World over, almost all the major players in the automobile industry have introduced electric
vehicles (EV) or Plug-in Hybrid Electric vehicle (PHEV) in the market. This is rather in response to their
commitment to a green environment, reducing carbon footprints and reducing the emission rates. With the
unveiling of the National Electric Mobility Mission Plan 2020, by the government of India manufacturers
areurged to adopt electric vehicles in an attempt to reduce our dependence on imported oil. The ambitious
plan aims to produce 6–7 million electric vehicles by 2020 with an estimated fuel saving of 2.2–2.5 million
tonnes of oil. Electric vehicles when utilized for feeding back the energy to the grid play a very important
role in Demand response in Smart grid environment. This will play a major role in the Power sector
scenario. Though this technology is yet to pick up in India, it has become popular in the western countries.
Lot of Research work has been carried out and research work has been published, which is reviewed
in this paper.
PSO based Multi-Criteria Placement and Impact Evaluation of Distributed Generators in Indian Context
Naveen Jain, Singh S N and Srivastava S C
This paper presents a new approach for optimal placement of Distributed Generators (DGs) utilizing
a generic multi-objective performance function considering dynamic relevance (weight) factors and
various levels of the DG penetration. The suggested approach can place the fixed size as well as the
variable size of multiple DGs in single or multiple stage(s), considering any type of load model. The
technical performance of the system, with the dynamic relevance factors is found to be better than with
the fixed relevance factors approach. The effect of considering system constraints on the DG size and
its location has been studied. A look up table approach is also suggested to place the DG at locations
other than the most optimal one. The impact of the DG placement on the system voltage profile and line
loss has also been investigated on 33-bus and 41-bus (Indian system) distribution systems. The critical
cases with extreme DG output power and distribution load demand are simulated on these systems to
study the technical viability of the DG planning under such circumstances.
Vol. 9, No. 2, June 2013
Design and Implementation of Micro-Stepping Drive of Stepper Motor for Solar Array Drive Assembly using FPGA
Sachin Angadi, Satyanarayana Kumari B and Saikumar H V
This paper describes the design of a control system for a micro step driving method of stepper motor
using VHDL. The control system so designed is employed in the application of Solar Array Drive
Assembly (SADA) in terrestrial solar plant and in satellites. This solution uses a digital controller
with Sine-Cosine variation to control the currents of the two phases of the motor, making them change
according to the orthogonal sinusoidal scalar form curve, fulfilling the micro step driving of stepper
motor and improving its position control precision by hundreds of times. At the same time, this driving
method solves problems such as large noise, resonance and non-even step angle and so on. The work
presented in this paper implements the control system in Xilinx ISE.
Combined Effect of Deterministic and Stochastic Variables on Comparative Performance Analysis of 110 kW A-Si PV and C-Si PV based Rooftop Grid Tied Solar Photovoltaic Systems in Jodhpur
Vikas Pratap Singh, Vivek Vijay, Ravindra B, Chaturvedi D K and Rajashekhar P Mandi
The main objective of this paper is to review the state of the art of IIT Jodhpur Rooftop installed
110 kW PV systems. This is done analyzing the operational data of 110 kW PV systems (43.30 kW
located in Block 1 and 58.08 kW in Block 2). Performance analysis depends on three basic term
of solar PV. How much energy do they produce? What level of performance is associated to their
production? Which are the key parameters that most influence their quality? During the year 2011, the
PV systems in Jodhpur, India have produced a mean annual energy of 1290.64 kWh/kWp in block-1
and 1290.64 kWh/kWp in Block-2. As a whole, the location of Solar PV system is the main reason
of energy variability and system output. The overall mean Performance Ratio is 75% in both Blocks.
Solar power variability depends on the two variables, deterministic and stochastic variable. In last few
years researcher work on finding deterministic variable such as system losses (module efficiency, DC
cable losses, inverter losses and AC cable losses) but these deterministic variables are not enough to
give accurate forecasting so with the help of combined effect of these both variable give accurate plant
performance and reliable solar power forecasting for solar power scheduling and dispatchability.
Vol. 9, No. 2, June 2013
12. Dynamic Simulation Study of IGCC Power Plant: Impact of Coal Flow Change
Rasesh Kotdawala, Thirugnanam C and Nagaraj Kumar T V S
Coal usage is becoming more widespread in India because coal reserves are much greater than oil
and gas reserves combined together and the cost of coal is also very attractive. For reducing the
carbon emissions when coal is utilised for power generation, Integrated Gasification Combined Cycle
(IGCC) technology can be used, which uses a gasifier to turn solid or somewhat pulverised coal into
gaseous form which is called as synthesis gas (syngas). IGCC has the potential to generate power with
better efficiency or efficiency on par with the existing technologies. It is very important to understand
operational and design aspects of the IGCC technology via dynamic simulation studies. The paper
discusses the transient behavior of the commercial scale IGCC plant through dynamic simulation
studies. The major components of IGGC plants-gasifier, Heat Recovery Boiler (HRB), syngas clean up
system, gas turbine, HRSG and regenerative steam cycle were modeled in Modular Modelling System
(MMS). The objective is to study the effect of coal flow to the gasifier on the transient behaviour of
the plant parameters.
Evaluation of Corrosion Properties of Cenosphere Aluminium Composites
Prashanth T, Narasimha Murthy K and Umesh C K
Industrial processes generate certain solid by-products, the disposal of which is of serious environmental
concern. The solid by-products are mainly fly ash from the power generation industry, metallurgical
ore residues and slag, slurry from the mining industry, etc. Among these, fly-ash utilization continues
to be an important area of national concern due to India’s dependence on thermal power generation for
its energy supply. Particle reinforced Al matrix composites are emerging out as potential materials to
replace conventional alloys/metals. These metal matrix composites (MMCs) find extensive applications
in many engineering activities because of their lightweight, high stiffness and high specific strength.
This paper discusses the manufacture of cenosphere-aluminium composites. Based on varied ratios
of the reinforcement phase, fly-ash cenospheres – 6061 aluminium composite with better features in
terms of strength, corrosion resistance and hardness and has been developed. The current work also
brings out the structure – property correlation of cenosphere-aluminium metal matrix composite. It is
found from the microstructure studies that there is a homogeneous distribution of the cenospheres in
the matrix of Al 6061. The corrosion studies show that there is an increase in the corrosion pitting of
the cenosphere-aluminium composite.
Vol. 9, No. 2, June 2013
Influence of Nickel on Abrasion and Erosion Wear Behavior of Thin and Thick Section Permanent Molded Austempered Ductile Iron for Wind Turbine Hubs
Narasimha Murthy K, Sampathkumaran P, Seetharamu S and Kumar R K
The influence of 2.0% nickel on thin and section permanent molded austempered ductile iron samples
were investigated for abrasion and erosion behavior. The section sizes of samples were varied at two
levels viz. 25 mm and 50 mm. Wind turbine hubs which were subjected to wear and erosion were made
from thin and thick section PMADI castings. The austempering temperature and time were optimized
for improved wear behavior and strength at 3000 C for 60 mins. Nickel additions showed about 7%
improvement in the wear resistance of thin section PMADI samples over unalloyed PMADI samples.
For the purpose of comparison, sand-cast austempered ductile iron was also evaluated for abrasion,
erosion resistance. Thin section (25 mm) PMADI samples subjected to austempering at 3000 C for 60
mins showed improved abrasion and erosion behavior in addition to higher strength values over thick
section (50 mm) PMADI and sand cast ADI samples. Further these data were analyzed with structure
property correlation and were well supported by light photomicrographs.
The Journal of CPRI, Vol. 9, No. 3, September 2013
THE JOURNAL OF CPRI - Vol. 9, No. 3, September 2013
Fuzzy Logic based Short Term Load Forecasting
Amit Jain and Santosh Kumar Kukkadapu
With increasing complexity of modern power systems, good quality load forecasting has become the
necessary requirement for secure and reliable operation of power grid. Short term load forecasting
plays vital role in daily operation of power grid to provide right inputs for the commitment of power
generation units and dispatch. Fuzzy logic based short term load forecasting is described in this paper.
To obtain the next-day load forecast, fuzzy logic is used to modify the load curves on selected similar
days. A new Euclidean norm with weight factors is used for the selection of similar days. The proposed
fuzzy logic based short term load forecasting method presented in the paper is illustrated through the
simulation results on a typical data set.
Placement of Distributed Generation in 33/11 kV Radial Distribution System to Minimize Power Losses, Improvement in Voltage Profile and Reliability using Genetic Algorithm
K Amaresh and V Sankar
Integration of renewable energy based distributed generation units provide potential benefits to
conventional distribution systems. The power injections from renewable DG units located close to
the load centers provide an opportunity for system voltage support, reduction in energy losses and
reliability improvement. Therefore, the allocation of DG units should be carefully determined with
the consideration of different planning incentives. In this paper, a simple method for real power
loss reduction, voltage profile improvement which is based on voltage sensitivity index analysis is
considered. Power flow analysis is done using the forward-backward sweep method, the placement and
sizing of DG in distribution system are determined using optimization.The objective is to improve the
reliability indices. The placement and size of DGs are optimized using a Genetic Algorithm. To evaluate
the proposed algorithm, the 10 bus distribution feeder is used. The results illustrate the efficiency of
the proposed method.
The Journal of CPRI, Vol. 9, No. 3, September 2013
Predictive Reliability Assessment in the Power Distribution System
K V Harikrishna, V Ashok, P Chandrasekhar, T Raghunatha and R A Deshpande
The electrical utilities are facing market conditions and therefore have to plan and operate their
distribution systems in a cost effective way. This implies that the customer’s requirement on reliability
i.e. availability has to be balanced towards the cost for obtaining the same. An effective way to solving
this issue is by the use of quantitative assessment of reliability, i.e. reliability indices, which is based
on probability theory. However these methods require input data that defines the condition for the
system and its components. is to predict the future behaviour based on collected data and measured
The reliability assessment is normally used to evaluate performance of the distribution system network.
The reliability of power Distribution system can be calculated by different reliability indices.This paper
describes the reliability indices for two feeders of one is an industrial feeder and another one is an
urban feeder. A software module (Reliability Assessment Module-RAM) has been used and the results
of two practical distribution feeders are compared to benchmark the performance and operation of the
power distribution system.
Analysis on Emerging Trends and Challenges in Smart Grid Automation
Technology from Generation to Distribution
Balakrishna P, Rajagopal K and Swarup K S
Power System or Grid is defined as the collection of group of devices, components that make a physical
system to generate, transmit and distribute electricity to the end users. Complexity of power system
has grown tremendously in the last few decades, facing new challenges during its operation. In order
to meet some of these challenges there is a definite need of automation which helps in automatically
operating & controlling the power system under various circumstances. The new era of smart grid
in the 21st century has made automation really a need to operate grid under the dynamics of rapid
load changes, makingthe system more time sensitive towards faults and failure modes. Automation
being one of the critical components in realizing smart grid, this paper tries to present an overview
of grid automationtechnology trendfrom generation to distribution over the past few years andfuture
opportunities& challenges.
The Journal of CPRI, Vol. 9, No. 3, September 2013
Switching Transient Mitigation By Controlled Switching:
A Literature Survey
Anjani Pandharkar, T N Date, B E Kushare
Energy is one of the major inputs for the economic development of any country. This is the reason
electrical power system network is expanding day by day to serve the increasing energy demand of the
nation. There are many types of equipments in power system.A circuit breaker is protective switching
equipment and hence, it plays a very important role in the power system. To maintain the adequate
reactive power for voltage control in EHV & UHV system, frequent switching of capacitors and reactors
is required through circuit breaker.These are the few applications where switching transients can occur
frequently.Apart from this unloaded transformer and transmission line energization also leads to inrush
current and over voltages in the system. This condition results into electrical and mechanical stresses
and sometimes may lead to equipment failure. Controlled switching has become an economical and
technically viable solution to reduce switching transients. This paper presents a literature survey based
on switching transients and controlled switching aspects.IEEE transactions,conferences, CIGRE reports
andvarious catalogues of the controllers are referred for the literature survey. This survey ishelpful for
the researchers working in the area of controlled switching, circuit breaker manufacturers,controller
manufactures and power utilities.
Diagnostic Field Testing and Condition Assessment of
Power Transformers in Service
K Mallikarjunappa, Chandrashekar D Keri, V Vaidyanathan,
T R Afzal Ahmed, Dillip Kumar Puhan
In this era of reformation, liberalization and unbundling of electricity markets, asset management
in power sector has assumed greater prominence. Power transformers are key components in any
transmission & distribution network and loss of a transformer can have an enormous impact on
reliability and availability of power supply and on cost. As society is more and more dependent on
electricity for development, the utilities are under pressure to meet the ever-growing demands for
reliable power supply. Economic factors are the main consideration and in order to minimize capital
expenditure on new equipment, it is a common policy among utilities to maximize the use of existing
networks by operating at their design capability. This can be achieved by according importance to the
maintenance practice. A survey of the literature indicates that there are more failures of transformer
due to poor maintenance, improper operation, severe weather conditions and manufacturing and design
defects than due to insulation ageing. The utilities shall have a systematic O & M practice that include
diagnostic tests for condition assessment and health checkup of the equipment. The objective of the
condition monitoring tests is to detect the first symptoms of incipient faults, ageing development or
other problems and monitor their evolution to enable the operator to take appropriate action to avoid
major failure. The paper reviews the results of various diagnostic tests including dielectric response
methods for condition assessment of power transformers.
The Journal of CPRI, Vol. 9, No. 3, September 2013
Review of Power Transformer Mechanical Condition Assessment Techniques
Shubhangi Patil, B E Kushare
Today’s trend of global electricity market has created a competitive environment in power industry.
To reduce operational cost, optimize usage of critical equipments, to improve reliability and customer
service, fast and enhanced diagnostic techniques are being developed and utilized in power industry. In
recent years, transformer fault diagnosis has become an interesting research area.This paper presents the
literature review done in the area of power transformer designs, failure causes and effects and on existing
and new diagnostic techniques to generate the baseline for the development of mechanical condition
assessment system. The survey has included the 90technical reports and papers from CIGRE, IEEE
transactions and conferences along with standards and books based on power transformer conditioning
and monitoring. In this paper an attempt has been made to analyze, generate real data based approach
for development of enhanced and automated diagnostic system for mechanical faults detection.
Modeling, Control and Maximum Power Point Tracking (MPPT) for optimal Battery charging from Solar Photovoltaic (SPV) system
H S Sudhakar, Gujjala B Balaraju, K Pradeep, M Siddhartha Bhatt
MPPT algorithms are necessary in PV applications because the MPP of a solar panel varies with the
irradiation and temperature, so the use of MPPT algorithms is required in order to obtain the maximum
power from a solar array.Over the past decades many methods to find the MPP have been developed
and published. These techniques differ in many aspects such as required sensors, complexity, cost,
range of effectiveness, convergence speed, correct tracking when irradiation and/or temperature change,
hardware needed for the implementation or popularity, among others. Among these techniques, the
P&O and the InCond algorithms are the most common. These techniques have the advantage of an
easy implementation but they also have drawbacks, as will be shown later. Other techniques based
on different principles are fuzzy logic control, neural network, fractional open circuit voltage or short
circuit current, current sweep, etc. Most of these methods yield a local maximum and some, like the
fractional open circuit voltage or short circuit current, give an approximated MPP, not the exact one.
In normal conditions the V-P curve has only one maximum, so it is not a problem. However, if the PV
array is partially shaded, there are multiple maxima in these curves.
The Journal of CPRI, Vol. 9, No. 3, September 2013
Application of Synchronised Phasor Measurement Technology in
Renewable Energy Systems
K Sornalatha, N Rajkumar, K Pradeep, C Viswanatha, Giridhar P Kini
This paper throws light on application of synchronised phasor measurement in renewable energy
systems. Power generation from renewable energy system connected to the grid is highly dynamic,
nonlinear which needs to be monitored continuously for efficient and reliable system. There are
various methods of monitoring of power from renewable energy system to grid. Nowadays, Time
synchronisedphasormeasuring method proves to be a revolutionary method for power system monitoring.
Synchronised PMU has wide application such as wide area monitoring, Real time monitoring, post even
analysis, visualization, state estimation etc. They are employed in micro grid and distributed generation
plants mainly for solving islanding issues. This paper summarises the synchrophasor application and
its future scope in renewable energy system.
Z-Source Inverter for Maximum Power Tracking in
Solar Photovoltaic System
K J Shruthi, Rajashekar P Mandi, C Viswanatha, Giridhar P Kini
This paper discusses the various inverter topologies used in solar photovoltaic system for electrical
energy. This paper gives comparison between the conventional type of inverters i.e. voltage source
inverter (VSI) and current source inverter (CSI) .New z-source inverter topology is proposed which
will overcome the drawbacks in VSI and CSI. Pulse width modulated (PWM) signals are generated
for the power semiconductor switches of the z-source inverter for controlling the power to the grid.
The characteristics of this inverter are used to obtain maximum power tracking control and delivering
to the grid.
Load Emulators for Testing of Power Supplies - A Review
Vani Vijay, Giridhar P Kini, C Viswanatha, S JothiBasu
All newly designed power electronic equipments are to be tested as per the standards, so as to verify
the response of the equipment under various load conditions. For this, different linear, non-linear and
dynamic loads are to be applied to the equipment in accordance with the applications. Load emulation is
the process by which the actual load is replaced by a flexible system which can mimic the characteristics
of the actual load. A regenerative operation can be implemented in power electronic emulators. Thus
by using load emulators for testing, the energy lost in testing of equipments can be reduced to a great
extent. Here a review of various types of load emulators is presented which are intended for various
types of applications along with some experimental results obtained in various research studies.
The Journal of CPRI, Vol. 9, No. 3, September 2013
Analysis of Solar Power Variability Due to Seasonal Variation and its Forecasting for Jodhpur Region Using Artificial Neural Network
Vikas Pratap Singh, Vivek Vijay, S H Gaurishankar, D K Chaturvedi, N Rajkumar
In 21st century solar power variability is an important issue due to grid integration. In these days
grid integration is very popular because of heavy load. So solar power, wind power and conventional
power are basic sources of grid integration. Solar power is playing a key role in grid integration. The
main objective of this paper is to analyse solar power variability due to seasonal variation in Jodhpur.
Jodhpur is known as sun-city for an average 320 sunny days in a year. Average solar insolation available
in Jodhpur city is 5.7-6.0 kWh/m2 per day. This is second highest insolation in the world. In this
paper, the Solar power variability analysis is carried out based on the data collected from a typical 43
kW amorphous silicon solar photovoltaic system installed in Jodhpur. Mansoon, winter and summer
seasons are used for analysis of variation in Photovoltaic Generation due to change of solar insolation.
Output of solar photovoltaic system depends on solar insolation and in this paper we have analysed
the variation in solar power according to rainy, winter and summer seasons and used artificial neural
network to predict the power output from PV system. The paper showed that proposed ANN model
is more accurate and study of variability in solar power can help in plant operation, power scheduling
and dispatchability.
Grid Stability and Control in DFIG Wind Turbines using
Dynamic Voltage Restorer
S Arjuna Rao, Swaraj Kumar Das and B V Raghavaiah
The development of wind power in India began in the 1990s, and has significantly increased in the
last few years.India has the fifth largest installed wind power capacity in the world.As of 31 Jan 2013
the installed capacity of wind power in India was 18551.7 MW, mainly spread across Tamil Nadu
(7134 MW), Gujarat (2,884 MW), &Maharashtra (2310.70 MW)whichare leading the top. All across
the world, the demand for electricity from renewable energies is constantly growing. To meet this
demand, wind farms must be as operable as conventional power plants and better integrated into the
grid control mechanism. Our wind power plants should actively support the grid, fulfilling all necessary
requirements and ensuring reliable energy supplies even during breakdowns. Wind power plants feed
the grid with controlled reactive power. This allows for a constant voltage control, sustaining the line
voltage. Even at temporary voltage dips the wind power plant remains connected to the grid and helps
to keep it stable. If any frequency fluctuations occur the effective power of our wind turbines should
automatically adjust according to the needs.
The Journal of CPRI, Vol. 9, No. 3, September 2013
Shake Table Experiments of Surge Arrester for
Evaluation of Ground Motion Amplification
N Srujana, R Panneer Selvam, R Ramesh Babu, Katta Venkataramana
The support structure of a surge arrester within the substation is considered for the experimental and
finite element study. Support structures are generally used in a substation mainly for the electrical
ground clearance purposes but also it protects the mounting equipment with respect to earthquake loads.
The paper is aimed to find out the acceleration amplification levels at base of the support structure
at severe earthquake loadings even when it is mounted on steel support structures. Seismic tests are
carried out experimentally on shake table. The behavior of the support structure is found satisfactory.
No material losses are resulted. Finite element studies are also included in the paper. The finite element
model predictions are agreeable to the experimental results.
Safe Method to Erect Towers with Electro-Rheological Fluids
Kalyana Sundaram, Ameya V Datrange,
Ranjit Patil, Prashant Ravella, Sandeep Mungala
Power sector is one of the fastest growing sectors expanding to remote and inaccessible sections of
the Indian Subcontinent. High customer expectations of uninterrupted power supply exist even during
occurrence of natural calamities via the distribution and transmission networks. It is a challenge to
erect any tower in a short period. Erection of towers involves safety issues of the workmen falling
down. Hence there is a need to look at non acrophobic devices such as telescopic towers which can
be operated from close to the ground level. Our paper here describes one method to address such
a challenge whereby a tower could be constructed quickly without the need of support scaffolding
arrangements and without the need for workmen to suffer batophobia.
The Journal of CPRI, Vol. 9, No. 4, December 2013
THE JOURNAL OF CPRI - Vol. 9, No. 4, December 2013
Transients Instability Detection and Prevention Control Schemes
Parvathi S and Shanti Swarup K
Effective real time monitoring and analysis of power system has become very important from the
point of view of power system stability and security. Recent research in literature has identified that
it is possible to determine the critical group of generators and hence predict the generators going out
of synchronism. However, a clear mitigation scheme from a wide area perspective has not yet been
identified. The main contribution of this paper deals with the post prediction of instability phase. After
the identification of the critical generator or group of generators, effective actions such as load shedding
should be initiated. The work targets in finding the optimal location where load is to be shed using the
rotor angle algorithm and the Jacobian based distribution factor sensitivity
Fuzzy Logic Based UPFC Controller for Damping Power System Oscillations
Senthil Kumar N
In this paper, a fuzzy logic controller is proposed for a Unified Power Flow Controller (UPFC) installed
in a single-machine infinite-bus power system. The Fuzzy Logic controller is mainly equipped to damp
power system oscillations. Simple Fuzzy Logic controller using mamdani-type inference system is used.
The Fuzzy Logic based UPFC controller is designed by selecting appropriate controller parameters
based on the knowledge of the power system performance. The effectiveness of the new controller is
demonstrated through time-domain simulation studies. By comparison, it can be seen that the proposed
UPFC controller can provide good performance for different operating conditions of power system.
The results of these studies show that the designed controller is robust enough to damp power system
oscillations with change in system operating conditions.
Energy Storage Sizing to Improve the Distribution Line Performance
Mahesh H Pandya and Mohan V Aware
This paper presents a sizing methodology and optimal operating strategy for a battery energy storage
system (BESS) to improve the operating efficiency of distributed networks. The alternate solution to
network reinforcement is given by providing the optimal energy storage device. The targeted issues
of loss reduction and possible local voltage control are investigated. The relation of feeder losses with
requirements of the energy storage requirements are presented through mathematical modeling with
actual distribution network parameters. This investigation is carried out with different types of the
feeders viz. urban, rural and industrial. The case studies are presented with actual site data obtained
from the Maharashtra State Distribution Company of India.
The Journal of CPRI, Vol. 9, No. 4, December 2013
Short Term Load Forecasting using Soft Computing Techniques
Chaturvedi D K, Sinha A P and Vikas Pratap Singh
Soft computing techniques are extensively used for electrical load forecasting in the past such as ANN,
Fuzzy Systems, GA etc.. ANN has some limitations, such unknown structure of ANN, Decision of
neuron type, problem of training data and time, stuck in local minima etc. To overcome the drawbacks
of ANN, a Generalized Neural Network (GNN) has been proposed. In this paper, different variants of
GNN have been proposed to improve its performance such as GNN integrated with wavelet transform
and trained with adaptive genetic algorithm and fuzzy system to forecast the short term week day
electrical load. Performance of the proposed algorithm is compared with other GNN and its other
variants on the basis of prediction error.
Theoretical Analysis of Islanding Phenomenon in Distributed Generation
Karthick S and Shanti Swarup K
Distributed generation faces several issues when integrated to power grid in large scale. Unintentional
islanding is one such issue which needs to be addressed. Several methods already exist in literature
to detect islanding instant like positive feedback method, passive method and communication based
methods. This paper provides an overview of islanding phenomenon, theoretical explanation on
islanding and the dynamics of the typical distributed generation system in islanded mode.
Life Line Characteristics of Solid Insulation under Electrical Stress
Aditya Bafna, Nirmal Shankar, Ashish Jain, Pravin Kothari and Madhu Palati
Insulating materials subjected to electrical and thermal-electrical stresses exhibit life line characteristics
which show a tendency to reach an electrical threshold. Their fit is investigated with reference to several
sets of data derived from accelerated life tests performed on different insulating materials.
Life line models provide the estimates of failure time percentiles at selected probabilities and stresses
so that life curves at fixed failure probabilities can be drawn. These characteristics should help in the
choice of compatible thermal and electrical stresses for the design of insulation systems, apparatus and
The tests to be conducted to plot the characteristic curves involve Class B insulation (up to 8 specimens)
under three active stress levels. Subsequently, using the data acquired, the Weibull probability
distribution curves are plotted using STATISTICA software.
The Journal of CPRI, Vol. 9, No. 4, December 2013
Optimization of Micro grid with Demand Side Management
Jayadev V and Shanti Swarup K
In a smart grid environment, economic operation means not only to economically sched­ule the generation,
but also to schedule the load. In a Microgrid (MG), which comprises of intermittent DGs (eg. solar
and wind energy sources), the need of Demand Side Management (DSM)/ Demand Response (DR)
becomes significant. The key point in DSM is to shift the load to some other point of time, on the other
hand shifting the load causes inconvenience to the customer, and hence it has to be minimized. This will
become a multi-objective optimization problem to minimize the cost of generation and inconvenience
caused due to the shifting of loads. In this work the authors consider an industrial/ commercial MG
with one solar source, two diesel generators and one battery, with the assumption that the utility grid
uses dynamic pricing. The objective function contains discontinuous function which will be difficult
to solve using conventional optimization techniques and hence Genetic Algorithm based solution is
proposed. The simulation results show that there is a savings with DSM compared to without DSM.
Optimal Hybridization of Renewable Energy Systems
to Improve Energy Efficiency
Rajashekar P Mandi and Udaykumar R Yaragatti
Energy is the prime mover of the economic growth and developmental process. To enhance the energy
security of India, use of renewable energy is the utmost important. Electrical energy is the richest
form of energy which is having an important role in Industrial growth. Depleting fossil fuel resources
which form about more than 60 % of Indian energy generation cannot prime the growth process that is
sustainable. They need to be gradually replaced by renewable sources of energy, which are perennial in
nature. The increasing gap between power supply and demand is alarming the power industry to work
hard in reducing the gap. In order to achieve the sustainable energy growth with the increased population
and energy demand and to provide more energy to the rural populations, the non-conventional and
renewable energy sources need to be installed and used [1]. The energy resource like solar radiation
& wind data are measured, the energy availability, reliability of energy systems and economics of the
systems are carried out by using a HOMER and MATLAB Simulink software. This paper discusses
about the improving of energy efficiency by hybridization of different forms of renewable energy
sources with respect to energy availability, reliability, cost, ease of operation and maintenance, etc,
with detailed discussion.\
Integration of Renewable Energy System Solar PV with Diesel
Rajashekar P Mandi and Udaykumar R Yaragatti
This paper describe the sizing of solar PV, DG set and battery bank Hybrid Power System (HPS) for
different configuration for share of solar &diesel power. Different configurations for integration of solar
PV with diesel energy systems are explained in detail. The energy availability and economics of the
integrated energy system are highlighted
The Journal of CPRI, Vol. 9, No. 4, December 2013
Modeling & Analysis of Power Management by Grid Connected PV System
Grishma Patel
Now-a-days the DG system based on PV technology is becoming more popular with rang of power
generation is between 1 KW to 50 KW because of its advantages like safe, clean, quiet to operate,
reliable, maintenance free, flexible etc. Main objective of this paper is the Modeling of PV System
components & Analysis of power management is carried out using the MATLAB/SIMULINK platform
for different load & different insolation levels. In this paper it is presented that whenever load demand
is less than PV capacity then remaining power is supplied to grid and whenever the load demand is
more than PV capacity then load will consume the required power from the grid.
HERIC Configuration Based Back To Back Converter With Reduced Losses For Regenerative Load Applications
Vani Vijay, Giridhar Kini P, Viswanatha C and Jothi Basu S
Back to back converters are used in many applications including machine drives and HVDC links. It is
a combination of AC to DC and DC to AC converters with topologies suitable for the application. Here
a single phase converter topology is developed by combining a Z source network and HERIC inverter
which operates with lesser losses and more controllability. Compared to conventional inverter model,
the conduction losses are much less in HERIC configuration. The Z source network help in boosting
the DC voltage level so as to obtain the required level of AC output. This back to back converter is
mainly meant for regenerative load application which can be utilized in equipment testing. The power
drawn by the converter can be regenerated to supply back to the utility grid there by it is possible to
conduct equipment testing without wasting energy. The details of the proposed configuration and the
output waveforms are explained. Also a comparative study of the losses in conventional converter and
proposed converter is presented.
Design and Performance Evaluation of Standalone Solar-PV System Using Interval FLC Based MPPT Controller
Neha Adhikari, Bhim Singh and Vyas A L
This paper deals with the design, modeling and performance evaluation of standalone solar-PV (PhotoVoltaic) system using interval type FLC (Fuzzy Logic Controller) based MPPT (Maximum Power
Point Tracking) controller. The proposed system is designed for a 5 kW solar-PV generating system.
The system consists of a solar-PV array connected with the single phase VSI (Voltage Source Inverter)
through a MPPT controller and an LCL filter is used to feed the power to the consumer loads. The
design procedure and modeling of the system components and controller is presented in detail. The
performance of the system is evaluated in steady and dynamic system conditions to validate its design
and model. The voltage controller is designed to maintain the dc link voltage and performing under
varying input voltages. The output voltage and current regulator is designed to maintain the power
quality under varying consumer loads and results are presented for THD (Total Harmonic Distortion)
which are found under the limits of 5%.
The Journal of CPRI, Vol. 9, No. 4, December 2013
Single Phase Transformerless Grid-Tied Inverter with Maximum Power Point Tracking for Solar Photovoltaic Roof-Top Systems
Shruthi K J, Rajashekar P Mandi, Pradeep K, Viswanatha C and Giridhar Kini P
The key requirements for the control of the solar photovoltaic (SPV) energy conversion systems
are to achieve very fast yet quite accurate tracking of the maximum power point under rapidly
changing environmental conditions and to obtain efficient unperturbed tracking operation under steady
environmental conditions. In this work, a high-performance Maximum Power Point Tracking (MPPT)
technique, based on one cycle control (OCC), is proposed to meet these challenging requirements. This
paper proposes single phase z-source inverter with maximum power point tracking using OCC for solar
photovoltaic power generation. OCC is based on output current adjustment according to the voltage of
photovoltaic array so as to extract the maximum power from it. A 1 kW grid-tied roof-top system is
designed using the OCC method for MPP. Analysis & simulation using MATLAB tool, is carried out
to validate the proposed technique.
Operation of Charge Controllers in Distributed Multi Source
(Solar and Wind) Hybrid Power Generating Systems
Sudhakar H S, Gujjala B Balaraju, Pradeep K and Siddhartha Bhatt M
In large PV hybrid power systems, battery management is critical due to the continuous operation of
the power system, the limited power available for temperature control in the battery room, and the high
cost of maintenance.Charge controllers are required in solar or wind power generating systems where
electrical energy storage is required in these systems. Optimal charging is required in order to improve
the performance and life of the batteries. The charge controllers are used for optimal charging of the
entire system. The different types of charge controllers, terminologies, set points and importance of
hybrid system are explained in this paper. The shunt and series type charge controller’s current and
voltage regulations are shown and battery current and voltage characteristics according to the source
availability and load applied are also shown for the understanding.The studies of a system of the three
sources (Solar, wind and diesel generator) includes than it in practice to optimize performance by 35%
by optimal charging of battery using charge controller.
Heat Transfer Analysis of a 7.5W LED Load with Passive and Active cooling for Constant Luminance Applications
Sangmesh, Gopalakrishna K and Venkatesh K
The aim of the present work is to study the thermal performance of a 7.5 W LED load with passive
and active cooling and validation of the results using FEA analysis. In order to get a high cooling
effect for 7.5W LED load, thermo electric cooling uses the peltier effect to create heat flux between the
junctions of two different types of materials. A peltier cooler, which transfer heat from one side of the
device to the other with the consumption of electrical energy, depends on the direction of the current.
A peltier device (Active heat transfer device) is provided with the LED module for removal of heat
generated in the module. The assembly (LED +heat sink +fan +peltier cooler) was tested for varying
input power. With the use of the assembly, the junction temperatures were considerably reduced. The
results indicate that, the assembly(case 4) performed better than any other cooling combinations. The
validation of experimental data was done through FEA analysis.The differences between FEA results
and the experimental values were 24%.
The Journal of CPRI, Vol. 9, No. 4, December 2013
Evaluation of Iron Aluminide-Fly Ash Nanocomposite Prepared by Attritor Milling and Equal Channel Angular Extrusion Consolidation
Malur Srinivasan, and Dipak Chavda
An experimental investigation was conducted to evaluate the crystallite size and microhardness of
mixtures iron aluminide (Fe3Al) powder and Class C fly ash in different volume percentages, subjected
to attritor milling and consolidation using Equal Channel Angular Extrusion (ECAE) process. Design
if experiments was employed to select the lowest size of fly ash to be mixed with pre-milled iron
aluminide powder. The results indicate that crystallite sizes n the low nano-range are obtained in all
iron aluminide-fly ash compacts, qualifying the compact as a nanocomposite. The microhardness of
the nanocomposite is lower than that of the nano-iron aluminide indicating the possibility of porosity
being developed in fly ash during processing.
Cement-Carbon Nanotube Composites and Their Multifunctional Behavior:
A Brief Overview
Malur Srinivasan
The author has tried to provide a brief overview of the constituents of cement-carbon nanotube
composites, their interactions and some examples of research on functional behavior of the composites.
Many interactions are at the nanoscale and the functional behavior is strongly affected by such factors
as the type and features of carbon nanotube, the proportion carbon nanotube in cement, the method
adopted for dispersion of carbon nanotube in cement-water mixture, admixtures and others. Though
MWCNT’ (Multiwalled carbon nanotube) is by far the more widely used, little information is available
other than the diameter and length of the MWCNT, pointing out towards the need for optimization of
the MWCNT features. There is thus a huge potential for optimization of structure-property relationships
in the constituents of the cement-carbon nanotube composites and interested researchers are encouraged
to study the full publications cited in this paper and the references cited in each publication.
The structure and properties of carbon nanotubes are first reviewed, to indicate why this material is so
unique. Next, nanoscale structure development in cement is reviewed, with the hope that further research
on nanoscale interactions between carbon nanotube and cement will lead to more improvements in the
functional behavior of the composite. Finally, papers dealing with chosen functional properties relevant
to cement-carbon nanotube composites composite, are reviewed.
The Journal of CPRI, Vol. 9, No. 4, December 2013
The Wear & Friction Characteristics of Glass-Epoxy Composites for Coal Handling Parts in Thermal Power Plants
Bharathi V, Ramachandra M, Srinivasa S, Sampathkumaran P,
Vynatheya S and Seetharamu S
The comparative performance of plain Glass-Epoxy (G-E) system with graphite(2.5wt.%) as filler has
been reported for slide wear and friction behavior using pin-on-disc setup under varying loads and
sliding velocities. This material is intended for use in coal handling systems. Besides slide wear and
coefficient of friction (μ) measurements, examination of worn surface features by scanning electron
microscope has been carried out to support the slide wear data. The slide wear data reveal that with
increase in sliding speed, wear loss of both G-E composite and G-E plain system increase. Further it
is seen that the G-E graphite filled system shows the least wear loss compared to plain G-E system.
This trend is observed for all the three loads employed in this work. It is observed that the graphite
bearing and plain G-E samples display a rise in the value of μ, when both load and sliding velocity are
increased. The coefficient of friction of graphite G-E shows the least compared to plain G-E system
irrespective of the load and the sliding velocity employed.
The Journal of CPRI, Vol. 10, No. 1, March 2014
THE JOURNAL OF CPRI - Vol. 10, No. 1, March 2014
Switching and Power Frequency Transients in EHV Systems
A Review and Case study
Meera K S and Santosh Kumar Patro
Overvoltages caused by transients are important in a power system as they cause stresses on electrical
equipment. Majority of power system failures are directly or indirectly related to transient problems
rather than steady state operation. The insulation level of each element in a power system is governed
by the transient voltages originating as a result of lightning, short circuits and switching actions. In
contrast to lightning, switching overvoltages originates on the system and is inherently measured in
terms of the system voltage.
With the adoption of 400 kV voltages and above, it was clear that switching surges created in the system
would determine the cost and strength of the major insulations to ground. This paper gives an insight
to the electromagnetic transient phenomenon - switching and power frequency overvoltages and case
study results of simulation for these overvoltages for a typical Indian 765 kV system.
A Novel Dynamic Power Controller Based VSC-HVDC Line for Power Evacuation from Independent Power Producer
Geetha R S, Ravishankar Deekshit and Ghamandi Lal
This paper presents the analysis of a Voltage Source Converter based HVDC (VSC-HVDC) system
applied for evacuation of power from a medium size Independent Power Producer (IPP) with a
contractual requirement that a minimum quantum of the installed capacity is to be transmitted to
the permission granting agency’s grid substation. The balance power could be sold by the IPP to any
other customer through open access power transmission. In the system considered, at sending end, AC
power is supplied from the IPP to a DC line and also to an AC line. The DC line transmits pre-defined
amount of power (equal to 60% of net power available after auxiliary consumption) to the agency’s
grid substation and the AC line facilitates transmission under open access. The AC line is connected
to the central grid’s substation. At the receiving end, the agency’s grid substation is interconnected to
the central grid substation through another AC line. For such a transmission system requirement, a
high degree of control is necessary and VSC-HVDC technology emerges as a suitable option. In this
paper, a detailed simulation of power flow controllability using a novel active power controller under
different generation levels of IPP is carried out and the results are presented.
The Journal of CPRI, Vol. 10, No. 1, March 2014
Node Ordering Scheme of Large Scale Power Systems
Using Sparse Matrix Techniques
Prabhu S, Chandrasekar S and Kaliappan P
Power flow is the basic tool for power system analysis which reveals the system operation in a steadystate mode for evaluation of the power system planning and operations. The accuracy, simulation
time, computer storage size and convergence of any model used depend largely on the size of the
bus admittance matrix of the system under study. This paper, therefore, presents the study of the bus
admittance matrix of the different systems with sparse techniques. And also analyze the number of
zeros and non-zeros element in the different systems with minimum ordering schemes. The proposed
method is validated using a 5-bus, 30-bus, 118-bus and 300-bus systems. The results are presented in
graphical form and discussed. The sparse Matrix techniques show that as the system is increasing in
size, the percentage of stored bus admittance elements decreases and changing the order of the nodes
gives more impact on the size of the system. Thus, an appreciable reduction in the computer memory
required to store the bus admittance matrix and in turn reduces the overall simulation time.
Dynamic Stability Enhancement of Power System Using Fuzzy Power System Stabilizer Under Different Loading Conditions
Chandrashekhar P K, Srivani S G, Shyam Sundar Sand Rashmi
The power system is dynamic in nature and is constantly being subjected to disturbances. It enters into
dynamic instability when there is an imbalance between generation and varying load demand which
calls for use of Power System Stabilizer (PSS). PSS is a device which provides additional signal to
the voltage regulator derived from speed deviation, excitation deviation and accelerating power for
damping critical oscillations. The PSS used should be capable to produce appropriate stabilizing signals
against a wide range of operating conditions and disturbances. For this purpose, a PSS based on fuzzy
logic control under multi-operating conditions is proposed in this paper. The performance of Fuzzy
Logic based PSS(FLPSS) applied to Single Machine Infinite Bus (SMIB) system is studied for three
different operating conditions; nominal load, heavy load and fault condition in transmission line. For
Fuzzy PSS, speed deviation and acceleration are taken as input. The system is simulated in SIMULINK
platform and its dynamic response is analyzed for system without PSS and with PSS. The results are
compared for system with Conventional PSS and Fuzzy Logic PSS.
Challenges in Preparation of Detailed Project Report for High Voltage Distribution System (HVDS) Scheme – A Case Study
Devender Rao K, Venugopal M and Deshpande R A
High Voltage Distribution System (HVDS) is being implemented in many utilities across our Nation. In
rural areas, loads particularly agricultural consumers are widely dispersed and low tension lines of 433
V run for long distances to feed a small load. Two or three low tension spans are to be laid to fetch a
load of one pump set and such 30 to 40 pump sets are connected on each distribution transformer of 63
kVA or 100 kVA. These transformers are generally overloaded due to long LT lines and more number
of consumers connected. This paper describes about the various aspects in preparing HVDS scheme on
an overloaded 100 kVA transformer and its Cost Benefit Analysis (CBA).
The Journal of CPRI, Vol. 10, No. 1, March 2014
Real Time Simulation of Multi-Area Power System with Polar Fuzzy Controller
Chaturvedi D K, Manmohan, Rahul Umrao and Vikas Pratap Singh
The Fuzzy Logic Controller has proven its worthiness for nonlinear complex systems. Multi-area power
system is quite complex and nonlinear in nature. In this paper, Fuzzy logic controller (FLC) is developed
for three area nonlinear power system. But there are inherent drawbacks of FLC such as its performance
depends on number of rules, long computation time, large memory requirement etc. To overcome these
problems, a polar fuzzy controller (PFC) is proposed to control the load frequency deviations in multi
area power system. The PFC works on the basis that an angle acts as an input and controller response
as an output. In conventional PI controller and FLC, two gains are to be tuned;whereas the PFC needs
only one gain to be tuned, because the angle of PFC is calculated from the ratio of frequency deviation
and the integral of frequency deviation. Hence, only one gain is sufficient to tune it. In PFC, only two
rules are sufficient in the rule base. The work is extended to test the performance of proposed PFC in
real time environment with the help of OPAL-RT simulator (OP 5142 v 10.2.4).
Wide Area Monitoring, Protection and Control:
Requirements and Applications in Power System Protection
Dijin Divakaran and Amit Jain
Due to the large scale network complexities, system wide disturbances in power systems are a
challenging issue for the power industry. When a major power system disturbance occurs, protection
and control actions are required to stop the degradation of the system and restore to a normal state
thereby minimizing the impact of the disturbance. Improvements in planning and operation of the grid
could be achieved by Wide Area Monitoring, Protection and Control (WAMPAC) Applications. The
purpose of wide area monitoring system is to monitor, assess, enable and automatically take necessary
action to mitigate the harmful effects due to disturbances or faults in the system. This paper discusses
in details WAMPAC. The present work also gives an overview of the Phasor Measurement technology
and it benefits, requirements and applications for WAMPAC strategies.
DLMS Data Connectivity Architecture for Energy Meters
Mohammed Farooque Khan, Amit Jain and Paventhan A
DLMS is a platform that provides communication between meter and data collection devices. The
companion specification provides secure and efficient transfer of electricity data. Many of data exchange
approaches have been proposed to develop an open standard. In this paper, a client /server model of the
DLMS / COSEM architecture with HDLC as the data-link layer and parameter identification of energy
meters has been discussed with some of the issues also discussed in Indian context.
The Journal of CPRI, Vol. 10, No. 1, March 2014
Reducing Auxiliary Power of Induced Draft Fans in Coal Fired
Thermal Power Plants by Energy Audit
Rajashekar P Mandi and Udaykumar R Yaragatti
This paper describes the various opportunities for reducing the auxiliary power of induced draft fans
in coal fired thermal power plants. The auxiliary power used by induced draft fans forms about 0.9
to 1.18 % of the total gross energy generation for 210 MW to 800 MW power plants. ID fans are the
second largest (in rating) motor in a thermal power plant after Boiler Feed Pump (BFP). The detailed
energy audit of auxiliary equipment in various thermal power stations, operational optimization and
appropriate control system had shown ample scope for improving the energy efficiency of induced draft
fans. The implementation of energy conservation measures reduce the average auxiliary power used
by ID fans for 210 MW plant from average value of 1.18 % to 0.90 % of gross energy generation and
the energy conservation schemes are economically attractive with a payback period of 1 to 5 years.
Deliverables of Re-configuration in Autonomous Micro-grids
Venkata Kirthiga M and Arul Daniel S
Distribution Systems with optimally sized Distributed Generators(DGs) placed at optimal locations
would become Micro-grids. These micro-grids operate either in non-autonomous mode (in conjunction
with the utility grid) or in autonomous mode (in the absence of the utility grid) depending on the
penetration level and sustainability of the DGs connected. This paper has suggested an optimal structure
for autonomously operated micro-grids by re-configuring the radial system into a weakly meshed system.
The deliverables of the proposed reconfiguration strategy in autonomous micro-grids are discussed
in detail in this paper. The proposed reconfiguration strategy is found to ensure continuous power
supply to the select customers of the micro-grid by enhancing a stable operation of the generators to
avoid formation of accidental islands on line outages and minimizing the distribution losses. MATLAB
code has been developed for the proposed methodology of reconfiguration and the standard 33 bus
distribution system has been used to validate the proposed algorithm.
Impact of Demand Response on Unit Commitment in Microgrid Environment
Manisha Govardhan and Ranjit Roy
Demand response program (DRP) aims to reshape an inconsistent load demand and motivates the
customers to reduce their energy consumption to get financial benefit. In this paper demand response
based unit commitment (DRUC) model is used to study the impact of DRP on generation scheduling
and total cost of the system. DRUC model describes the customer behavior for different incentive
values and variation in the price elasticity matrix. The simulation study is carried out with a low voltage
microgrid system with and without integration of solar and wind renewable sources (RS). It is found
from the results that with the increase in incentive value and price elasticity matrix elements, customers
tend to participate more in DRP which increases customer benefits and reduces total utility cost. It is
also observed that integration of RS significantly reduces the total cost of the system.
The Journal of CPRI, Vol. 10, No. 1, March 2014
A Simplified Methodology for Determining Optimal Location and Capacity of Solar PV Distributed Generation to Reduce Losses
Amit Jain and Venkata Srinath N
This paper presents distribution load flow analysis for balanced radial system in conjunction with
Solar Photo-Voltaic (PV) distributed generation. The proposed approach utilizes Kirchhoff’s Current
Law (KCL) and Kirchhoff’s Voltage Law (KVL) carried-out on forward and backward sweep iterative
algorithm for the calculation of node voltages and currents flowing in radial branches. The power
generated from solar PV system is determined by developing a mathematical model of solar PV modules
that adopts to the Indian meteorological conditions. The distribution load flow analysis carried out by
taking into the effect of this Solar PV generation. Optimal location for the distributed generation is
determined by considering total system losses that can occur in 24 hours and the capacity to be installed
is based on desired voltage improvement. The proposed approach has been implemented on standard
69bus radial distribution network. The simulation results obtained with and without inclusion of Solar
PV generation are compared and discussed.
High Efficient Soft Switching Cuk Converter with Ripple Correlation Control MPPT for PV Applications
Mutta Krishna Murthy, Sandeep N and Kulkarni P S
This paper presents the application of “ripple correlation control (RCC)” maximum power point
tracking (MPPT) algorithm for photovoltaic (PV) system employing dc-dc Cuk converter to maximize
the output power of PV module. Soft switching commutation of the main and auxiliary switches at zerovoltage using active clamp technique allows the operation of the Cuk converter at very high switching
frequencies with reduced size of reactive elements and electromagnetic interference. The combination
of auxiliary switch, clamp capacitor and resonant inductor is used to exploit the advantage of high
efficiency with zero switching losses. RCC technique uses the high frequency signal ripple, which
makes it to converge asymptotically to the maximum power point independent of module configuration
and parameters. The operating modes of converter for different switching time intervals are analyzed
and design considerations are presented. The simulated performance of the converter with RCC MPPT
over conventional MPPT algorithms is presented. The MPPT methods are compared on the basis of
the time taken to track the maximum power point (MPP), steady state oscillations about MPP and
dependence on array parameters. To evaluate the viability of ZVS Cuk converter with RCC MPPT, the
entire system is simulated using MATLAB/SIMULINK platform for an 87 Wp solar PV system.
The Journal of CPRI, Vol. 10, No. 1, March 2014
14. Power Quality Monitoring and Control Using Virtual Instrumentation System
Arunshankar V K and Senthil Kumar N
This paper presents and develops a LabVIEW based mathematical model for power quality analysis
and enhancement. The different types of power quality problems such as voltage sag, voltage swell,
power frequency distortions, and harmonic distortions can be identified and controlled suitably.
Besides standard undisturbed three-phase voltage signal waveforms, six different categories of the
PQ disturbances characteristic for real-time power distribution networks can be simulated on the basis
of developed virtual instruments: voltage swells, sags, interruptions, high-order voltage harmonics,
swells with harmonics and sags with harmonics. Each of simulated PQ disturbances can be predefined
and easily changed according to user requirements, using various combinations of the control
settings implemented on the virtual instrument front panel. All computations are carried out using
LabVIEW 9.0.
Design and Analysis of Perturb and Observe MPPT Techniques
for Inverter in Photovoltaic System
Shruthi K J , Giridhar Kini P , Viswanatha C and Rajashekar P Mandi
Renewable energies are the most sought after alternatives for electric energy generation. The
improvement in semiconductor and power electronics technology has led to precise operation of system
at maximum power point, thus increasing the efficiency of the PV system. Many maximum power
point tracking (MPPT) algorithms have been developed in recent times which provide maximum power
tracking under varying conditions. Among the existing algorithms, perturb and observe (P & O) is the
most explored technique. In this paper a comparison between the conventional P & O and improved
P & O method is brought about. A MATLAB simulink based simulation study of PV module/ array is
carried out and both the MPPT algorithms are explored for z-source inverter in photovoltaic system.
Performance Loss in Solar Photovoltaic Array due to Non-ideal
Natural Conditions
Sudhakar H S, Gujjala B Balaraju, Pradeep K and Siddhartha Bhatt M
Performance of a SPV system is dependent on temperature, array configuration, solar insolation, and
shading across it. Shading can occur when the PV arrays/modules get covered by shadows of passing
clouds, buildings, etc., or even by shadows cast by other modules/arrays. As a result the ideal operation
of the PV systems is severely affected the P-V and I-V characteristics. The modeling of nonlinear currentvoltage characteristics of solar cells for performance prediction becomes difficult under the influence
of shading. Non-uniform solar radiation due to shadows casted by the other panels/modules, buildings,
clouds, etc. can cause maximum power to change drastically. Partial shading of PV installations has an
impact on its power production. For the simulated results it has been observed that 74.66% loss in I-V
characteristics and 85.41% loss in P-V characteristics respectively. The power losses in the individual
shaded cells would result in local heating and create thermal stress on the entire module/array resulting
in hot-spot formation.
The Journal of CPRI, Vol. 10, No. 1, March 2014
Studies and Analysis of Effects of Shading on the Performance of a
Solar-Photovoltaic System
Neha Adhikari and Vikas Pratap Singh
This paper presents the studies on the solar photovoltaic system in the partial shading conditions. The
standalone solar photovoltaic system for residential application of 2 kW power rating is considered in
the system analysis. The proposed system is using a set of batteries for energy storage with a flyback
dc-dc converter and a single phase voltage source inverter is designed with the controller to regulate
the power quality at the consumer end. The studies are carried out as case studies on the different
conditions of the shading and results are presented to analyze the PV output power and evaluate the
overall system performance. Based on the results obtained few measures are suggested to keep the
check on the performance in such conditions.
Input and Output Distortions in the Operation of Stand alone Solar PV Inverters and Method for Compensation
Vani Vijay, Giridhar Kini P, Viswanatha C and Jothi Basu S
Inverter and power conditioning circuit is the most important part of solar PV system which is responsible
for providing the AC output as per the requirement of the application. The presence of AC harmonics
and DC ripples in the inverter is still an unavoidable drawback, even though it has reduced to a great
extent in past two decades. This paper presents a detailed study of distortions in the AC and DC sides
of commercial standalone single phase Solar PV inverter and the effect of the same in the application.
The harmonic content is evaluated by loading the inverter using electronic loading. The reduction
in distortions in the AC and DC sides by utilization of a high impedance network on the DC side of
the inverter is also evaluated by simulation. A comparative study of harmonics and DC ripples in the
inverter under test and the simulated impedance source inverter is also presented.
Modelling and Analysis of 3-Phase Inverter for Grid Connected
Solar PV system with Harmonic Compensation
Lakshmanan S A, Amit Jain, Rajpourhit B S
Renewable Energy Sources (RES) are getting a great attention due to ever increasing power demand,
environmental issues, and thrust toward sustainable development. The power produced from the RES
like solar, wind etc. is used by the stand alone system or the feed into the electric grid. In this paper a
3-phase Voltage Source Inverter (VSI) is modeled and analyzed for grid connected Solar Photovoltaic
(SPV) system. Mathematical model of three phase VSI and LC filter circuits are derived using state
space analysis and Sinusoidal Pulse Width Modulation (SPWM) technique is proposed for 3-phase VSI.
Harmonic elimination is done in VSI using by Pulse Width Modulation (PWM) technique by solving
the non-linear equations that are used to determine switching angles of an inverter. The switching
angle plays an important role to produce desired output by eliminating selected harmonics. The VSI is
simulated using MATLAB/Simulink platform and harmonic elimination is done by considering bipolar
switching case of the inverter. Various simulation results are presented to demonstrate the operation of
the inverter. The harmonic spectrum analysis is carried out and discussed for the proposed harmonic
elimination method.
The Journal of CPRI, Vol. 10, No. 1, March 2014
Solar Photovoltaic Power Generation Forecasting Models and Techniques
Vikas Pratap Singh, Vivek Vijay, Chaturvedi D K and Neha Adhikari
The various forms of solar energy - solar heat, solar photovoltaic, solar thermal electricity, and solar
fuels offer a clean, climate-friendly, very abundant and in-exhaustive energy resource to mankind. Solar
power is the conversion of sun light into electricity, directly using photovoltaic (PV). The forecasting of
energy Demands have become concerns for facility managers, and predicting energy generation plays
a critical role in power-system management, scheduling, and dispatch operations. A reliable energy
supply forecast helps to prevent unexpected loads and provides vital information for decisions made
on energy generation and purchase. However, study of energy generation prediction by the photovoltaic
(PV) system has been limited over the years, especially concerning short-term predictions. This study
will helps in providing the details on different type of models and techniques of solar power forecasting.
Wind Energy Conversion System for Rural Application
Arjun M, Uma Rao K and Deshpande R A
This paper presents the use of induction generator with suitable control strategy for use as standalone wind energy conversion system. This may find application in remote rural areas where extension
of 11 kV feeder may not be feasible due to physical terrain and where drawing of line may not be
economically viable if loads are dispersed over wide area. This Induction machine is driven from a
prim em over which is usually a wind turbine. The stator terminals of the induction machine is
connected to a voltage source converter. The voltage source converter (VSC) is a three level diode
clamped VSC. The terminals of the converter are connected to a capacitor and a battery. The battery is
initially charged to 12 V and provides initial magnetisation for the Induction Generator. The terminals
of the stator are also connected to an induction motor represented by RL load. Control strategy has
been developed to keep the DC voltage constant irrespective of variation of load and rotor speeds.
The total harmonic distortion in the line voltage of the induction machine is ensured to be within
limits by employing three level converter. The proposed system is mathematically modelled using
SIMULINK/MATLAB. The simulated results validate the theory studied.
Assessment of the Potential of Three Attritor-milled and Consolidated Nanostructured Materials for Sliding Wear-resistant Applications
Malur N Srinivasan
This paper deals with the assessment of the potential of nanocrystalline tungsten carbide-cobalt (WCCo), titanium disilicide (TiSi2) and titanium silicide (Ti5Si3) for sliding wear-resistant applications.
All the materials were milled in a laboratory attritor and the milled powders were consolidated
using equal channel angular extrusion (ECAE) process in three cases and chemical consolidation
using polycarbosilane (allylhydridopolycarbosilane-AHPCS) in one case. The microhardness of each
consolidated sample was measured using a Vickers hardness tester. The crystallite sizes of WCCo, Ti5Si3 and TiSi2 consolidates after ECAE and Ti5Si3 after attritor milling and prior to chemical
consolidation were determined using X-ray diffraction and, the relationship between the crystallite size
and microhardness in these cases was examined. The data on microhardness of all the samples was
analyzed with reference to current literature to assess the potential of each consolidate for sliding wearresistant applications. The results indicate that attritor-milled Ti5 Si3 consolidated using polycarbosilane
as the binder appears to have the best potential for sliding wear-resistant applications. The experimental
data reported in this paper was obtained by former graduate students under the direction of the author
at Lamar University.
The Journal of CPRI, Vol. 10, No. 1, March 2014
Design Optimization of Single Axis Thrust Magnetic Bearing Actuator
Dash S K and Shanti Swarup K
Design optimization of Active Magnetic Bearing (AMB) is important from the point of view of reliable
and high speed operation. They are widely used in fly wheels, wind generators, high temperature
applications, etc. Design and development of large air gap AMB is a challenge, This paper presents the
modeling and design optimization of a large air gap AMB using open loop position stiffness. In this
work, a goal seeking optimization methodology is employed for double acting AMB system where a
combination of higher (CRGO electrical steel) and lower saturating magnetic material (Mu metal) is
used. Adaptive Response Surface Method (ARSM) was used as a tool for optimization. A less variant
position stiffness across 1500 microns air gap was arrived at after getting optimized design variables
constituting geometry and excitation current parameters using above comprehensive optimization
method. This investigation opens up a new way to attain position stiffness in AMB system which is
less sensitive to positional variation of rotor in air gap.
The Journal of CPRI, Vol. 10, No. 2, June 2014
THE JOURNAL OF CPRI - Vol. 10, No. 2, June 2014
Comparison of PSO and RCGA for Optimal Location of STATCOM for Improvement of Transient Stability of Power Systems
Arunjothi R and Veena H S
In electrical power systems, reactive power compensation plays an important role in transient stability.
Shunt flexible AC transmission system (FACTS) devices are being used in controlling the reactive
power flow to the power network and, hence, the system voltage fluctuations and stability. Static
synchronous compensator (STATCOM) is one of the shunt connected FACTS devices. The primary
purpose of STATCOM is to support bus voltage by injecting (or absorbing) reactive power, but it is also
capable of improving the power system stability. In this paper, an interconnected two-area test system
with actual transmission line model is used to show the effectiveness of Particle Swarm Optimisation
(PSO) and Real Coded Genetic Algorithms (RCGA) algorithms for determining the optimal location
for power system stability improvement.
Impact of FACTS Controllers on the Dynamic Stability of Power Systems
Senthil Kumar N
The availability of flexible A.C. transmission system (FACTs) devices such as Static Var compensators
(SVCs) and Static Compensators (STATCOMs), has led their use to control reactive power flows in
transmission lines and system bus voltage. In addition to voltage control these devices can also be used
effectively for improving the small signal stability of the power system and improve system damping.
The objective of this paper is to explore the impact of the shunt connected FACTS devices namely
Static Var Compensator (SVC) and Static Compensator (STATCOM), on the small signal stability of
a single machine infinite bus system. A single machine infinite bus system is chosen to analyze the
damping capabilities in a detailed manner.
Evaluation of Inter Regional Power Flows in Planning Studies
Shyam Sundar S and Chandrashekhar P K
Power System Transmission Planning involves huge investment in the Power Sector. The network
condition, the available load and generation are the factors to be considered for proposing the power
transfer between regions. However if the envisaged power flow could not be achieved due to
constraints after commissioning of the Transmission Lines or Sub-Transmission Lines it could lead
to huge financial loss to the Utilities. Hence a case study of 14 bus known network with different
contingencies is brought out in this paper to visualize the limitations in inter regional power transfer in
spite of available generation to be exchanged within the regions.
The Journal of CPRI, Vol. 10, No. 2, June 2014
Mitigation of Subsynchronous Resonance in Power System
through STATCOM and Auxiliary Controller
Vipin Jain and Narendra Kumar
In FACTS devices, auxiliary signals are widely used to enhance damping and mitigate Subsynchronous
Resonance in Power System. Subsynchronous Resonance occurs due to series capacitor in Power
System. In this paper a novel auxiliary controller of STATCOM is designed with auxiliary signal ωg i.e.
accelerating frequency of generator rotor mode. Auxiliary controller is superimposed on conventional
PI controller. The study system is IEEE First Benchmark Model. Alone PI is not able to damp all the
modes of First Benchmark Model.
High Impendance Fault Detection in Distribution System under
Distributed Generation
Manohar Singh
Conventional power distribution systems are radial in nature, characterized by a single source feeding
a network of downstream feeders. Location of faults in such power networks is very challenging when
fault resistance is quite high. In distribution systems, fault location algorithms primarily utilize the
fault current amplitude for deciding the nature and location of the faults. However, the distribution
systems become radial nature when distributed generation sources are connected with them. Under
such circumstance mere magnitude of fault current is not sufficient to locate and classify the fault
on the power feeders. Additional fault informations are required for identification of faults in the
interconnected power distribution systems.
This presented paper suggests a novel algorithm, which can detect the high impendence fault based
on transient behavior of fault currents. The proposed algorithm utilizes the transient energy content of
the high impendence fault signals for detecting the faults in the distribution networks. The PSCAD/
EMTDC software is used for simulation for the faults in the power network under study.
An Efficient Fault Detection Algorithm for Micro-Grid
Majarikar Vikrant Jiwanrao and Shanti Swarup K
This paper proposes an implementation procedure and performance testing of an algorithm comprise
of Cumulative sum algorithm and power flow methods for fault detection in micro-grid systems. The
Cumulative sum algorithm is found to be better than the traditional methods in the presence of noise,
system frequency deviation, and other uncertainties for radial system. By monitoring the power Flows
between buses along with cumulative sum algorithm, detection of faults in micro-grid system is carried
out. The proposed digital Fault detection is implemented experimentally for performance testing on
a test micro-grid system. Several transient disturbances viz. grid connection, single-phase to ground
fault, 2phase fault, 3phase to ground faults, etc. occurring in different parts of the test micro-grid
system are investigated experimentally.
The Journal of CPRI, Vol. 10, No. 2, June 2014
Characterization of Marx Generator
Madhu Palati
This paper discusses the characterization of 200 kV, 20 J mini Marx generator. Marx generators are
extensively used in very high voltage fast pulse generation. Capacitors are the major components
of Marx generator, apart from the capacitance of the capacitor the other parameters such as internal
inductance (Equivalent series Inductance) and Equivalent series resistance (ESR) has significant effect
on the output current waveform. The internal inductance of the capacitor, ESR and the discharge path to
the load circuit has to be kept as minimum as possible so as to achieve lower characteristic impedance,
higher peak current, faster rise time and reduced Full Width Half Maximum(FWHM). Therefore there
is a need to determine the internal inductance and ESR of Marx generator. Short circuit discharge test
is conducted on the Marx generator to determine the value of total inductance of Marx generator during
erection. From the determined value of total inductance of Marx generator LT and erected capacitance
of the Marx CT, ESR is estimated from the PSPICE circuit. Also maximum output of Marx is estimated
using the PSPICE circuit.
Significance of Air Cooled System Over a Gas Cooled System in
Large Rotating Electrical Machines
Abhay Kumar Khairwar, Venkateswarlu G, Mondal N R and Raghavaiah B V
Short circuit generators are used to deliver the short circuit power in testing laboratories. During
operation at the time of field excitation a large amount of heat is generated. The dissipation of this heat
has to be evacuated to improve the generator efficiency and its reliability. The generator cooling goals
are to minimize drag or Windage loss, keep generator internals clean, minimize electrical, mechanical
and corrosion problems, and maximize generator output.
The purpose of the cooling is to dissipate generator thermal losses by forced circulation of coolant, may
be gas, water or air in a closed circuit through the different parts of the generator. This paper explains
the methodologies adopted to cool down the electrical machines like generators and to provide the safe
working atmosphere to the personnel’s working around it and also emphasizes on challenges to handle
the gas cooling system compared to the normal air cooling system. In this paper the actual cooling
system is also addressed, used in 1500 MVA Short Circuit Generator.
The Journal of CPRI, Vol. 10, No. 2, June 2014
Development of Intelligent System for Induction Motor Fault
Diagnosis in Ceiling Fan
Chaturvedi D K, Devendra Singh and Vikas Pratap Singh
A variety of fan faults occur in our day to day life such as electrical faults(winding faults), mechanical
faults (broken rotor bars, eccentricity, bearing faults) etc. To detect the fault, many motor variables
may be taken such as current, voltage, speed, sound, temperature and vibrations, so that the preventive
action may be taken before the occurrence of faults in the fan. Current signature is useful for finding
electrical faults such as stator faults etc. and acoustic signature is useful for finding mechanical faults
such as rotor faults etc. In this paper, the on line current, voltage, rpm and temperature reading of faulty
fan and healthy fan are recorded. These recorded signals are used to train a neural network so that it
is able to detect the fault.
Space-vector Based Equal Switching Strategy for Three-level Open-end Winding Induction Motor Drive
Srinivasan Pradabane, Narasimharaju B L, Srikanth N V and Deshpande R A
This paper proposes a new space-vector based pulse width modulation strategy for a three-level openend winding induction motor drive. The proposed method incorporates both the clamping and switching
duties of the inverters within every 60o span of the rotation of the reference space vector.The proposed
scheme neither requires sector identification nor lookup tables for the generation of the gating pulses.
The switching pattern adopted in the present work ensures equal clamping duty and switching duty
for both the inverters which are electrically isolated from each other to suppress the zero sequence
currents. The switching strategy ensures the usage of all the clamping states thus making the drive
system possible for maximum utilization of the switching resources. The proposed strategy is simulated
using MATLAB/Simulink and experimentally validated using dSPACE.
Effect of Radial and Axial Movement of Winding on Coherence Function in a 220/132 kV, 100 MVA, Auto Transformer
Shashidhar Reddy K, Vishal Kulkarni, Suryakalavathi M and Singh B P
The short circuit force generated in Powers Transformers due to system fault is known to cause movement
of the windings. Several diagnostic methods have been employed to identify the movement of internal
components of transformer e.g. Core, winding, coil bulging, coil twisting, Inter turn fault etc. The
methods include – Sweep Frequency Response Analysis, Current reflection time, wavelet transform
and Coherence Function (CF). The present work reports a detailed analysis of Coherence Function due
to radial and axial movement of coil by theoretically simulating the HV winding of 220/132 kV, 100
MVA autotransformer. The results show a variation in magnitude of CF for dominant frequencies and
that even a small change in radial or axial distances cause significant change in magnitude of CF. It is
observed that sensitivity of detection of winding movement by CF for minor faults is moderately better
than Frequency Response, since CF is related to the amount of linearity between input and output. It
is observed that CF and FRA are complimentary to each other.
The Journal of CPRI, Vol. 10, No. 2, June 2014
Performance Evaluation of Optical Fiber Ground Wire Cable
During Short Circuit Condition
Chandra Sekhar M, Santhosh J, Nanda Kumar V S, Sudhakar Reddy and
Rajaramamohan Rao Chennu
Optical ground wires (OPGW) are increasingly being used on overhead transmission lines throughout
the world. OPGW conductors protect the power line against lightning or short-circuit and provide
communication through optical fibers embedded inside the conductor. In case of conventional ground
wire, the permissible instantaneous temperature is limited by the highest allowable loss of tensile strength
of metallic materials caused by annealing and bird-caging. Since OPGW conductors are expected to give
protection to the embedded optical fiber, they shall meet a further requirement; i.e. the temperature of
the conductor shall not rise in such extent that it may cause degradation in the parameters of the optical
fiber. The highest temperature that the conductor may reach during and after short-circuit depends on
the conductor design. This paper describes the testing requirements and the performance evaluation of
typical OPGW conductor during short circuit condition as per IEEE Standard 1138.
Thermal Performance of Low Voltage Power Distribution Board Panel (PDBP) at Elevated Temperature
Viswanatha C, Vittal G P and Mohanbabu V
Thermal performance has been the subject of studies for LV equipment since decades and continues
to be the established practice to assess its continued usage of the equipment in service or installation
in the case of newly designed equipment. The PDBP being core of the distribution network to deliver
reliable quality power is investigated for its performance in ambient temperature and at elevated
temperature. Although, the equipment behavior is known at ambient temperature, its performance at
elevated temperature of 55˚C is seldom studied. Recently, the temperature in the globe is on the raise
leading to global warming and in addition there is requirement in industrial applications and high
temperate zones. The feasibility of electrical equipment in this elevated temperature condition is not
known. In this context, the equipment has been subjected to laboratory studies. The data obtained
showed the interesting results such as need of thermally endured materials in the configured system of
the equipment. The operation of the equipment in elevated temperature will accelerate deterioration and
reduction in the service life of the equipment. However, proper thermally endured components, thermal
design of the equipment will ensure for the application of the equipment in the elevated temperature.
The method of Temperature monitoring of the equipment by subjecting to service condition of operating
temperature and current can be applied as a means to study the thermal performance of equipment.
These aspects of the experimental method, the results obtained at ambient and elevated temperature are
discussed and investigated in this research work.
The Journal of CPRI, Vol. 10, No. 2, June 2014
Review of Silicone Rubber Nanocomposites for Outdoor Insulation
Ganga S, Moumita Naskar and Prasenjit Biswas
Polymer nanocomposites have attracted wide interests in high voltage insulation due to their excellent
electrical, thermal and mechanical properties. Among the new insulating materials extensively used as
high-voltage outdoor insulation, silicone rubber (SIR) has received the most attention. Indeed, SIRs are
gaining popularity as an effective counter-measure to handle the high voltage insulation problems. In
recent times nano sized fillers (Nano fillers) have sought great deal of research scholars’ attention and
has brought revolution in the polymer industry due to its better interaction with polymer. A relatively
less quantity of nanofillers in comparison to micro filler is reported to achieve the required properties in
SIR. In this review, the effectiveness of the most common nanofillers of SIR for dielectric applications
along with various dispersion methods is presented. But numerous experimental investigations on
nanocomposites have indicated a significant decrease in electrical, thermal, mechanical and surface
properties, due to the agglomeration of nanofillers. Agglomeration can be reduced by using modified
nanofillers & optimum quantity of nanofillers, high shear mixing, or by efficient filler dispersion methods
but it is almost impossible to entirely eliminate this effect with the presently available technologies.
Vibration Damping in Overhead Transmission Line Conductors
Praful R Dongre, Ramesh Babu R, Ananthbabu M D and Revanna D
Fatigue is a common cause for failure of conductors near associated hardwares and attachment.
Vibrations due to wind is a common cause for fatigue and frettingof conductors. Conductors under
the effect of high frequency and low amplitude are more prone to vibrations particularly in India and
other parts of the world. ACSR conductors have been a popular choice for overhead conductors due
to advantages in both electrical and mechanical characteristics and these conductors are more prone to
Aeolian vibrations. Vibration dampers are widely used to control Aeolian vibration of the conductors
and earthwires including optical ground wires. In this paper the author presents the performance of
vibration dampers on ACSR conductors. The author emphasizes the importance offor evaluating the
suitability of a damper for a particular overhead line by choosing appropriate design tension, type,
quantity and placement of vibration dampers to avoid failure of lines.
Improvement of Energy Efficiency of Boiler Feed Pumps in Thermal Power
Plants through Intelligent Prediction and Operational Optimization
Rajashekar P Mandi and Udaykumar R Yaragatti
This paper describes the various methods for enhancing the energy efficiency of Boiler Feed Pumps
(BFP) in thermal power plants. The specific auxiliary power used by BFPs vary between 2.2 to 3.6
% of the total gross energy generation for units ranging from 30 MW to 800 MW units. The average
specific power used by BFPs for 210 MW plants is 2.4 to 3.2 % of gross energy generation. The
energy efficiency improvement of BFPs by reducing the re-circulation flow, pressure drop across feed
water circuit elements, enhancing overall efficiency of BFPs, etc., are discussed with case studies. The
implementation of energy conservation measures reduce the average auxiliary power used by BFPs for
210 MW plant from average value of 3.6 to 2.3 % of gross energy generation and release an additional
power of about 10.9 MU/year for one 210 MW unit.
The Journal of CPRI, Vol. 10, No. 2, June 2014
System Efficiency (non-module) Considerations
in the Sizing Solar Photovoltaic Plants
Siddhartha Bhatt M
This paper presents a review of the energy efficiency in solar photovoltaic (SPV) systems with special
reference to quantification and improvement of non-module system efficiency. The system efficiency
(also called as performance ratio) is composed of photopic efficiency (losses in light energy before
actually interacting with the SPV cell surface) and electrical efficiency (losses in electrical energy
output generated by the module and before it is used by the load). Non module system efficiencies of
operating SPV plants range between 54.93 % to 70.16 % with an average value of 62.32 % and standard
deviation of 4.57 %. System efficiency considerations are important in design of power plants for given
end user loads. If the calculations are on the basis of kWpeak, a typical 100 kWpeak system gives a peak
output of 50-65 kW at the load point due to system efficiency and also lowering of module efficiency
due to non-standard operating conditions. System efficiency excludes auxiliary power (2-4 % of the
generated power), losses in battery (~20 %) due to storage component loss of energy generated due
to non-availability of the grid (for grid tied systems) and stochastic incident radiation loss (~16 %).
System efficiency presents possibilities of improvement to 75-80 % level through improved system
design and improved operation and maintenance practices.
Modeling of Grid-connected Solar Photovoltaic Energy Generation System
Neha Adhikari and Pardeep K
This paper coversthe design and modelling of a grid-connected solar photovoltaic energy generation
system. Solar-PV system with MPPT (maximum power point tracking) controller to track maximum
power point is designed with a dc-dc converter. The output of PV array is fed to the VSI converter
through a dc-dc converter. For regulating the output voltage and current under varying conditions,a
VSI is designed with closed loop controllers. Simulation model for this designed system is developed
in Simulink/Matlab platform and simulated results are presented to demonstrate its performance under
steady and dynamic conditions.
Simulation and Performance Study of Grid-connected Wind and
Photovoltaic Hybrid Energy System
Nagendra K, Vinatha U and Krishnamurthy N
Hybrid energy system (HES) includes several (two or more) energy sources with appropriate energy
conversion technologies connected together to feed power to local load/grid. HES allows a wide variety
of primary energy sources, frequently generated from renewable sources as the stand alone system for
rural electrification and also for grid extension. The objective of this work is to model photovoltaic
(PV) & wind grid connected HES using Matlab/Simulink. The model is useful for simulation of PV
& wind grid connected HES. Blocks like wind model, PV model, energy conversion system and loads
are implemented and the results of simulation model are also presented.
The Journal of CPRI, Vol. 10, No. 2, June 2014
Solar Power forecasting: The State-Of-The-Art
Vikas Pratap Singh and Kumar Vaibhav
In 21st century Renewable energy sources, especially Solar Energy, are to play a larger role in
Hybrid Generation. There exist a number of technological, environmental and political challenges linked
to supplementing existing electricity generation capacities with solar energy. Solar power forecasting
can avoid many of the balancing issues, if accurate forecasts of solar output are available. Anybody
trading in solar energy can negotiate a better price, if they have precise information about the volume
they have to sell at any particular time.
Analysis of DC Link Capacitor Performance and Capacitor Life In Back to Back Converters With Respect to Converter Switching
Vani Vijay, Giridhar Kini P, Viswanatha C and Jothibasu S
Back to Back converters are commonly used converters in many ac to ac conversion applications. Even
though Converters without intermediate energy storage element are developed, Those with DC link
capacitors still continue to be most popular due to the inherent advantages. The performance of such
converters is affected by the operation of DC link capacitors used. This paper gives a detailed study of
various types of back to back converters and considerations in DC link capacitor design and selection.
A MATLAB program is also developed to analyze the effect of RMS (Root mean Square) ripple current
and consequent effect on the life of the DC link capacitors in Voltage link back to back converters.
Optimization of Solar Photovoltaic Converters for Maximum Energy
Sudhakar H S, Gujjala B Balaraju and Pradeep K
Performance of a SPV system is dependent on temperature, array configuration, solar insolation, shading
across it etc. The conversion of solar energy using SPV modules comes with its own problems that
arise from the change in insulation conditions. These changes in insulation conditions severely affect
the efficiency and output power of the SPV modules. For improving the efficiency of conversion of
solar energy can be done by tracking the maximum power point of a PV module. There are so many
types of MPPT charge controllers for doing this important work in SPV system. A dc-dc converter is
essential in SPV system as it acts as an interface between the load and the SPV module. Three different
basic types of converters are explained in this paper without any non-idealities. There are other types
of dc-dc converters as well, but these converters from these three basic converters. Further by using
these dc-dc converters the performance of the MPPT algorithms can be done for improving the overall
efficiency of the SPV system.
The Journal of CPRI, Vol. 10, No. 2, June 2014
A Study on the Physical and Morphological Characteristics of Aluminum Cenosphere Composite Sintered at High Temperature in Microwave
Ananda Kumar M G, Seetharamu S and Jagannath Nayak
Aluminium Metal matrix Composites (AMC) have been fabricated through powder metallurgy route
comprising of Aluminum as matrix and reinforced with Cenosphere, a low density material in the
form of hollow and porous spheres. The densification of the composite has been carried out in an
advanced processing technique called the microwave sintering,which is rapid and economical. AMC
with Cenosphere addition of 40 volume % has been prepared and sintered at various temperatures. The
sintered composites have been studied for the mineralogical phases by XRD, morphology by SEM
and physical properties such as Density, Apparent Porosity and Hardness (BHN). The results obtained
have been compared with AMCs that were sintered conventionally. The microwave sintered samples
showed better properties in terms of Porosity, Bulk Density and Brinell hardness values compared to
the conventionally sintered ones.
Lithium Ceramics for High Temperature CO2 Capture: A Review
Lakshminarayana Bhatta K G, Seetharamu S and Sharon Olivera
Carbon dioxide capture and storage (CCS) technology is considered as promising option in the
portfolio of mitigation actions for stabilization of atmospheric greenhouse gas concentration as fossil
fuels continue to be the major source of energy in foreseeable future. Among the various options for
CO2 capture, the adsorption technology has been widely investigated as a means of an alternative
to absorption technology that is having many formidable problems. Recently there is a growing
interest in solid sorbents; those can efficiently capture CO2 in the temperature range of 200-700 °C.
Applications of high temperature adsorbents are envisioned mainly in sorption enhanced reformation
processes (SERP) and CO2 removal from hot flue gas/syngas. Lithium ceramics are important class
of materials in this category. This paper aims at a review of lithium zirconates and lithium silicates as
CO2 adsorbents. The focus is on various aspects of sorbents such as sorption capacity, mechanism of
adsorption, kinetic models, factors affecting the sorbent performance and methodologies developed for
performance enhancement. However, CO2 separating membranes made of lithium-based ceramics are
not discussed.
The Journal of CPRI, Vol. 10, No. 3, September 2014
THE JOURNAL OF CPRI - Vol. 10, No. 3, September 2014
Modelling and application of phasor measurement units for fault location
Anirudh Singh, Shikhar Dwivedi and Senthil Kumar N
Wide area monitoring and control using Phasor Measurement Units (PMU’s) will continue to remain
as one of the integral components of large power systems for different important applications in power
systems which includes dynamic state estimation, power oscillation monitoring, Transient Stability
Assessment etc. A wide area measuring system is composed of a PMU with High Speed Communication
Channels and Phasor data concentrators. This paper explores the modeling and application of a typical
phasor measurement unit to monitor voltage and current swings for different types faults and disturbances
in the standard four generator two area power system.
Out-of-step detection in emerging power systems key issues and challenges
Srinu Babu Matta and Seethalekshmi K
The electrical power systems function as a huge and highly interconnected network dispersed over a
large area. A balance exist between generated and consumed power, any disturbance to this balance
in the system caused due to change in load as well as faults and their clearance often results in
electromechanical oscillations inturn variation in power flows, this phenomenon is referred as Power
Swing. Stable power swings changes it operating point to new equilibrium point but unstable swings
collapse the equilibrium causes cascaded trippings inturn black outs or brown outs. In this paper,
several methods of power system Out-of –step detection are critically reviewed. Various OOS detection
techniques are discussed in brief; comparision of available approaches are examined and presented. The
key issues and challenges are OOS detection are highlighted. A vast collection of papers, books and
journals are listed, which is useful for interested researchers, power engineers and utility companies.
Development of adaptive distance relay for statcom connected
220 kv transmission line with wavelet transform and ANN
Ramchandra P Hasabe and Anil P Vaidya
A new scheme to enhance the solution of the problems associated with Transmission line protection
with Statcom connected is presented in this paper. Static Synchronous Compensator (STATCOM) is a
shunt type FACTS device connected at the midpoint of the transmission line to maintain the voltage
at desired level by injecting/absorbing the reactive power. This connection affects the performance of
distance protection relay during line faults. The fault detection is carried out by using energy of the
detail coefficients of the phase signals and artificial neutral network algorithm used for fault distance
location for all the types of faults for 220 kv transmission line. For each type of fault separate neural
network is prepared for finding out the fault location. An improved performance is obtained once
the neutral network is trained suitably, thus performance correctly when faced with different system
parameters and conditions.
The Journal of CPRI, Vol. 10, No. 3, September 2014
Adaptive polar fuzzy load frequency controller for
nonlinear multi-area power system
Chaturvedi D K, Rahul Umrao and Vikas Pratap Singh
Fuzzy logic controller is based on human experience. Human experience is encoded in the form of
fuzzy rule base to control the system. It is difficult to decide the size of fuzzy rule base. As the number
of rules increases the performance of controller is better. At the same time its complexity increases
which in turn affects the computation time and memory requirements. To overcome these problems,
a Polar Fuzzy logic controller (PFC) is proposed for the load frequency control problem of nonlinear
three area interconnected power system. In this paper, The PFC is made adaptive using Real Coded
Genetic algorithm- fuzzy system (RCGAF) approach. The performance of simple PFC and adaptive
PFC using RCGAF is compared with fuzzy and conventional PI controller.
Reliability constrained unit commitment problem incorporating
demand response program
Manisha Govardhan, Fenil Master and Ranjit Roy
In a restructured power market, the independent system operator (ISO) executes the reliability
constrained unit commitment (RCUC) program to plan a reliable and an economical hourly generation
schedule for the day-ahead market. This work presents probabilistic method for the incorporation of
the unavailability of the generating units in the solution of the Unit commitment (UC) problem. In this
paper, Gbest Artificial Bee Colony (GABC) algorithm is used for solving the UC problem, while the
evaluation of the required spinning reserve capacity is performed by using Loss of Load Probability
(LOLP) index. IEEE RTS 24 bus system is used to demonstrate RCUC problem for different reliability
levels. Considerable developments in the real time telemetry of demand-side systems allow ISO to use
reserves provided by demand response programs (DRPs) in a restructured power market. In this paper,
the hourly demand response is incorporated into RCUC for economic and reliability purposes. The
RCUC problem with Emergency Demand Response Program (EDRP) is tested on IEEE RTS 24 bus
system. Minimum cost results for each case and reduction in load demands for DRPs are formulated.
The Journal of CPRI, Vol. 10, No. 3, September 2014
A Study on the evaluation of sandwich busduct using temperature rise method
Viswanatha C, Vittal G P and Mohan Babu V
Different types of busducts like Isolated Phase Busduct, Segregated and Non Segregated Busducts
are used in Power Distribution Network which occupies voluminous, large space of the equipment.
Recently, Sandwich Busducts have come into vogue because of their compactness, light weight, low
impedance, and fire retardancy besides several other advantages. However Sandwich Busducts need to
maintain high quality conductors, superior design, high dielectric withstand voltage. These properties
would meet the requirements of electrical parameters but for the requirement of thermal specifications,
it is Temperature rise method widely employed to monitor the thermal performance of Sandwich
Busducts. In the present investigation, modular designed Sandwich Busducts are chosen and studied
using Temperature rise method. The samples of Sandwich Busducts are subjected to Temperature rise
method. The temperature at critical points of Sandwich Busducts are monitored and evaluated in the
light of International Specifications. Of the many inferences derived, the important observations at
thermal steady state for busduct, incoming and outgoing terminals have been obtained. The present
paper focuses on assessing the components forming Sandwich Busduct for their evaluation to apply to
field conditions in the Electrical Power System Network.
A review of health monitoring techniques of induction Motor
Chaturvedi D K, Md. Sharif Iqbal, Mayank Pratap Singh and Vikas Pratap Singh
Induction motor is singly excited and brushless,very simple, compact and extremely rugged in
construction and most reliable and low cost motor. Although, these motors are reliable but often
exposed to hostile environments during its operation which leads to early deterioration leading to the
motors failure. Faults and failures of induction machines can lead to excessive downtimes and generate
large losses in terms of maintenance and revenues. This paper deals with the study of identification
of different type of faults and the health monitoring techniques commonly used in induction motors.
The Journal of CPRI, Vol. 10, No. 3, September 2014
India’s largest short circuit generator & its salient features
Ramachandrappa V and Raghavaiah B V
Short circuit test is one of the very important tests on electrical power equipment to verify its design
aspects to withstand the critical severities under the condition of actual fault. To perform these tests
a high power source is required. This source can be a grid supply with a high fault level or can be
a high power short circuit generator. This paper gives the salient features of high power generator
installed at Central Power Research Institute (CPRI), Bangalore. This 2500MVA short circuit generator
is of highest capacity in the sub-continent of South Asia as on date. The design features are intricate
in nature and complex in terms of stator, rotor damper winding and stator end winding. This paper
presents the specification, design concept, constructional features, comparison between salient pole and
turbo type of generators and other auxiliaries of the generator. Mechanism of achieving the maximum
short circuit current is broadly discussed in this paper. This rare facility at CPRI meets high power
testing requirement for the electrical industry and utilities of India and other part of the world. In this
paper attempts are also made to bring out the highlights of operational features of capital intensive
2500 MVA SC generator. This generator has been used for short circuit testing of various power system
components over the period of time.
Traceability of high current measurements in short circuit laboratories
Nagaraj V, Maroti and Sudhakara Reddy S
To establish traceability for high current measurements, comparison tests of high current shunts in High
Power Laboratories have been carried out with STL reference shunts since 2005. This paper describes
the comparison test results of shunts in High Power Laboratory CPRI Bangalore. The test results shown
are the shunts tested for the comparison tests performed and most of the differences of the scale factor
with power frequency current between the reference shunt and those tested in participating
laboratories were less than 0.7 %.
Wavelet spectrum energy feature extraction based fault detection scheme for synchronous generators
Nagireddy Ravi and Narri Yadaiah
This paper presents a wavelet transform based fault detection scheme for synchronous generators
of power system equipment. The proposed method analyzes characterization of faults using a multi
resolution analysis and defines a novel feature extraction, which is called wavelet spectrum energy.
The multi-resolution signal analysis based on wavelet transform is utilized to decompose a given
signal into approximate and detail signals of original signal. The detail signal coefficients are utilized
for calculating wavelet spectrum energy. The fault detection technique utilizes the wavelet spectrum
energy as feature extraction to extract information of fault signals for transient analysis. The simulation
results show accurate discrimination of faults and also in characterization of internal and external faults.
The Journal of CPRI, Vol. 10, No. 3, September 2014
Performance study of grid-connected wind and photovoltaic hybrid energy system under variation of generation
Nagendra K, Dr. Vinatha U, Dr. N Krishnamurthy and Raghu N
The aim of this work is to analyze typical configuration of grid connected wind and photovoltaic
hybrid energy system. Nowadays hybrid energy systems (HES) are widely used because of inherent
problems with solar energy. HES includes several (two or more) energy sources with appropriate energy
conversion technologies connected together to feed power to local load/grid. These allowa wide variety
of primary energy sources, frequently generated from renewable sources as the stand alone system for
rural electrification and also for grid extension. Mainly the work presents the system response under
generation variation of HES with grid interface. Application represents a useful tool in research activity
and also in teaching.
Advances in steam turbines for solar thermal and integrated solar
combined cycle power plants
Siddhartha Bhatt M
This paper presents an overview of developments in steam turbines in general with particular application
to match concentrating solar thermal (CST) sources.
The design of solar steam generator which has a parabolic output profile is first presented. Technologies
for maintaining steady steam inflow into the steam turbine, viz., hybridization of sources like integrated
solar combined cycle (ISCC) and thermal energy storage (TES), cogeneration, trigeneration, etc., are
The developments in the steam turbine consist mainly of upgraded materials to operate at higher
steam inlet temperature and pressure, ungraded energy efficiency through 3-dimensional computation
fluid dynamics (CFD) design, increased fatigue life to withstand large number of cyclic operations,
increased dynamic response and automation in manufacture. It is concluded that while 3-d designed
steam turbines for elevated temperatures fulfill most requirements of CST power systems, fatigue life
improvement and better energy efficiency at part load, needs to be addressed.
13. Review of building integrated solar photovoltaic technology and its applications
Neha Adhikari
Building Integrated Photovoltaic (BIPV) systems is one of the most promising technologies and has
recently being experiencing a technological growth. There is a consensus that these advancements
may lead us to novel methods for domestic energy generation. Technical improvements, governmental
policy supportive and financial aids are some of the contributors to this development. However, the
amount of building integrated solar power generation as compared to other forms of solar electricity
generation methods is still negligible. In this study, a review is presented including the amount of work
done in this area and their findings. It summarizes the current state-of-art of these systems.
The Journal of CPRI, Vol. 10, No. 3, September 2014
Optimal placement and sizing of PV system and fuel cell
on distribution system for loss minimization
Vijay Gupta, Mukul Dixit and Ranjit Roy
In current scenario optimal placement and sizing of distributed generation (DG) on the distribution
system is drawing attention of electrical power utilities for minimization of real power loss. Power loss
minimization has some in built advantages i.e. power flow reduction in feeder lines, reduces stress on
feeder loading therefore increases reliability of the utility, fulfilled the load demand during peak load
period and reduction in consumer bill, etc. In this paper particle swarm optimization with constriction
factor approach (PSOCFA) for optimal placement and sizing of DGs (such as solar and fuel cell based),
heuristic approach is applied for reconfiguration of distribution system with the purpose to minimize
the total real power loss subjected to equality and inequality constraints in the distribution system
is presented. The results obtained after placement of Photovoltaic (PV) system, Fuel cell (FC) and
combination of both are shown by using PSOCFA algorithm applied on IEEE 33–bus radial distribution
system. It shows significant reduction in power loss with the improvement in voltage profile and voltage
stability index (VSI).
15. Power grids for high penetration of solar photovoltaic power plants- a review
Siddhartha Bhatt M
This paper presents a review of power grids which have high component (~ 80 %) of solar photovoltaic
(SPV) plants. It can be concluded that variability or infirmness of SPV is controllable to a large extent
through detailed probabilistic modeling of the variation patterns. The immediate, short term and long
term variation of SPV power plants has been discussed in depth. In a grid composed of a large number
of 1-50 MW plants, the dispatchable power can be scheduled to as high as 80 % of the declared capacity
in that time slot (since SPV varies in every time slot).
The Journal of CPRI, Vol. 10, No. 3, September 2014
Star rating and check testing of refrigerators - CPRI experiences
Gujjala B Balaraju
With growing population, economic and industrial development, the need to examine alternative
sources for generating electricity has become very important and the gap between Electrical power
demand and supply in the country is increasing, so it is essential to have efforts to conserve the
electricity by using energy efficient electrical products. There is always a possibility to save energy by
proper usage of energy efficient components to minimize the wastage of energy in electrical appliances.
The standards & labeling programme was launched for Air conditioners and Refrigerators by Bureau
of Energy Efficiency (BEE) during May 2006 on voluntary basis to minimize these wastages. The
manufacturers started displaying the star labels on the products from March 2007. The programme
was made mandatory from January 2010. In order to verify the correctness of the star labels,BEE has
introduced the check testing of the refrigerators and Air conditioners. The star rating evaluation involves
the measurement of energy consumption & volume with gross & storage volume of the refrigerator
along with pull down test as qualification requirement. The process of determining the energy rating
consists of measuring the tested energy consumption of the refrigerator. From December 2013 to July
2014, 15 numbers of refrigerators were check tested as per BEE requirements by CPRI. The star rating
of each of the models are calculated from the tests carried out at CPRI. Out of these 74% of the tested
refrigerators meet the star rating claimed by the manufacturer.
Design of AC-DC converter with reduced harmonics and
output ripples using active power factor correction technique
Vani Vijay, Giridhar Kini P, Viswanatha C and Jothi Basu S
AC-DC converters are very commonly used in many power electronics applications including
controllable sources and machine drives. Rectifier circuit results in harmonic distortions in AC side
and requires large capacitive filter for reducing DC ripples on the output side. Use of active power
factor technique can be utilized for solving this issue resulting in better performance of the converter.
It basically consists of boost converter with high frequency switching following the rectifier controlled
using a suitable microcontroller. This paper presents the detailed design and operation of Active power
factor corrected rectifier which operates with reduced THD and improved power factor there by
reducing losses in power flow and utility. Simulation of the designed converter and comparison with
conventional topology is also discussed.
The Journal of CPRI, Vol. 10, No. 3, September 2014
Improving performance of primary air fansin thermal power plants through energy conservation techniques
Rajashekar P Mandi, Seetharamu S and Udaykumar R Yaragatti
Primary Air Fans are the essential auxiliary equipment to provide the primary air to lift the pulverized
coal from mills to carry to burners and also to provide partial air for combustion. This paper describes
various techno-economical energy conservation measures for reducing the carbon emission by improving
the performance of Primary Air fans in coal fired thermal power plants based on the energy conservation/
audit study conducted in 28 numbers of 210 MW power plants in India. The best operating points for
pressure gain, flow, pressure drop across hydrodynamic resistive elements, equipment efficiency, power
input and specific energy consumption are simulated by using MATLAB and presented in this paper
with case study to validate the results. Optimizing the pressure at PA fan discharge, control of excess
air, pressure drop across APH and mills and maintaining the optimum primary air pressure at mills
thereby to maintain appropriate coal-air pressure at burners will help in reduction of auxiliary power of
PA fans. The implementation of energy conservation measures in a typical 210 MW coal fired thermal
power plant reduce the overall auxiliary power of PA fans by 0.26 % of gross energy generation and
also reduce the carbon emission by 4,056 t/year.
Study on the effects of coal-ash-slag deposition on boiler tubes
in a coal-fired thermal power plant
Malabika Roy, Arvind Kumar and Janardhana M
Coal combustion in a thermal power plant generates plenty of ashes, which gets melted at high
temperature. These melted ashes, i.e. slag, gets deposited on the external surface of the boiler tube
in the furnace and stick to it. This slag greatly affect the heat transfer, which leads to reduction in
the efficiency of the boiler. Also, slag deposition slowly corrodes the external surface of the tube.
In this paper, a typical slag deposited tube was collected from a coal fired thermal power plant and
metallographic analysis was carried out on this tube and the results were compared with an unexposed
tube of same material, diameter and thickness. It is concluded from the analysis that there are no
significant changes in microstructure, hardness values as well as inslag compositions.
Seismic response evaluation of substation equipment
Panneer Selvam R, Nampoothiri A N N and Ramesh Babu R
Electrical and telecommunication facilities are observed from the past earthquake data, as seismically weak
and prone to service failure due to suddenly applied seismic loads. Among them substation equipment
are the most vulnerable ones. A need for reliability of electrical equipment against vibrational hazards
due to earthquakes has become prime importance. In order to meet the basic requirements regarding
seismic qualification of equipment and thereby to ensure reliable power transmission, Earthquake
engineering laboratory capable of performing a diverse range of seismic qualification requirements
on equipment, sub-assemblies and components as per National and International standards has been
established at CPRI, Bangalore. Seismic qualification of few equipment carried out are presented.
The Journal of CPRI, Vol. 10, No. 3, September 2014
Computer aided Analysis and optimization of transmission line tower
Avinash M, Selvaraj M, Mohanbabu G and Prabhushankar G V
For economic reasons, our next generation overhead power transmission line towers will be built with
new design concepts in order to reduce the weight of the support structures. This paper discusses the
computer aided design and analysis carried out on a 220 kV Single Circuit transmission line tower built
with a combination of Circular Hollow Sections and Angle sections rather than built with only Angle
sections. After optimization, the comparative study is presented with respect to stresses, deflection and
weight of both Circular Hollow Sections and Angle sections towers. There is a saving in steel weight
up to 8% resulted when a Circular Hallow Section tower is compared with an Angle Section type. The
analyses results are compared with full scale test carried out at Central Power Research Institute (CPRI)
Bangalore, India are presented.
The Journal of CPRI, Vol. 10, No. 4, December 2014
THE JOURNAL OF CPRI - Vol. 10, No. 4, December 2014
Designing of supplementary controller for statcom for mitigation of
sub-synchronous resonance in series compensated power system
Vipin Jain and Narendra Kumar
In FACTS devices supplementary signals are widely used to enhance damping and mitigation of
Subsynchronous Resonance in Power System. Subsynchronous Resonance occurs due to series capacitor
in the Power Systems. High value of series capacitive reactance may destabilize low frequency mode
which is more dangerous. In this paper modeling of STATCOM with IEEE first benchmark model is
presented. Then a supplementary signal is developed which is capable to make the system stable for
all critical values of series compensation. The eigenvalues are presented for all four critical values of
series compensation.
2.Mathematical modeling and simulation of an observer based state feedback controller of a statcom to improve the voltage stability of power system
Papia Chakraborty and Satadeepa Bhaumik
Power demand in India is increasing significantly day by day due to the growing population, dynamic
economic growth and modernization. To meet such large and growing power needs our power system
is facing power quality problems inform of low power factor, poor voltage profile, voltage fluctuations,
voltage sag/swell etc. So it is indeed very essential to improve the power transfer capability of existing
networks. Installation of FACTS device in existing transmission network is an alternative way to
strengthen power transmission capability. A static synchronous compensator (STATCOM) is one of
the FACTS devices which is used to control the reactive power and it has also the ability to regulate
the grid voltage. Different control techniques are in use to control the amount of reactive power to be
injected or supplied by the STATCOM. In this paper, an OBSERVER based state feedback controller is
proposed for STATCOM to improve the voltage stability. Mathematical modeling for the controller is
also illustrated here. Simulation of observer based state feedback control of STATCOM is performed in
MATLAB/SIMULINK. The simulation result depicts the satisfactory performance of STATCOM with
proposed controller during three phases to ground fault condition.
The Journal of CPRI, Vol. 10, No. 4, December 2014
Comparative analysis of accelerating power input and speed input robust power system stabilizers
Javeed Kittur, Saikumar H V and Sharath Raj S V
The power system stability improvement by a robust Power System Stabilizer (PSS) using accelerating
power and speed as inputs is investigated independently in this paper. The objective of the work
presented in this paper is to design an accelerating power input robust PSS and a speed input robust
PSS to damp low frequency oscillations arising out of small and large disturbances. The robustness of
the PSS is ensured by placing all the eigen values within a specified contour in the s-plane. A nonlinear
constrained optimization technique has been applied for tuning the PSS parameters with the objective
of damping oscillations over a wide range of operating conditions to make the PSS robust. The design
of PSS is validated by performing nonlinear simulations for small and large disturbances.
Decision tree approach to dynamic security assessment
Nikhil Valluru and Shanti Swarup K
Dynamic Security Assessment (DSA) of power systems is an important study for real time application
in control centers. Historically, various numerical, methods have been adopted for carrying out DSA.
These are time consuming and computationally intensive. So faster and easily computable methods for
Security Assessment are the need of the hour. With the advances in technology, several new methods
which are more effective than the earlier adopted methods have been developed. One of them is the use
of Decision Trees (DTs) for Dynamic Security Assessment. The real time system data can be obtained
which helps in identifying current system operating condition and hence used it in predicting whether
the system is dynamically secure or not.As a result, making accurate predictions for the power system
operating conditions is an important task for the current power system research. The research mainly
interests in checking if the operating conditions are acceptable after contingencies.
Reliability analysis of protection system using neighbouring
line dependability failures
Nagarajupalle Naveen and Sankar V
In power system studies, the reliability of protection systems has a considerable effect on the reliability
of supply, and hence appropriate reliability models must be incorporated. A majority of studies conducted
assuming perfectly reliable protection systems, and hence do not take into account the effects of failure
scenarios in their operation.Modelling of the failure modes in protection systems associated with their
dependability and security features is essential for comprehensive evaluation of power system reliability.
There are relatively fewer works in the literature on power system reliability accounting for the impact
of protection system. In this paper, common mode failure operations such as dependability failures of
protection of neighbouring lines in a Power System network is considered. In an existing method, only
first order and second order failures of transmission lines are considered, whereas, failure modes using
higher order Cutsets are not considered. Expressions for reliability analysis are developed and software
has been developed using MATLAB. The results for sample systems are obtained and analysed. From
the results, it can be concluded that although probability of failure indices are increased as compared
to an existing method, the proposed method is more general, realistic and approximate analysis can be
carried out for any system having higher order dependable failures.
The Journal of CPRI, Vol. 10, No. 4, December 2014
Customers interruption cost estimation based on
reliability in power distribution system
Chandhra Shekar P, Deshpande R A and Sankar V
Reliability assessment of distribution network is an important subject due to increasing demand for
more reliable service with less interruption frequency and duration. An effective way to solving this
issue is by the use of quantitative assessment of reliability, measure the reliability indices to find out
the probability of availability and unavailability of supply. This paper describes the energy not supplied
to the customers in terms of customer kWh loss and revenue loss to the customers and the revenue
loss to the utility in profit making areas is presented for two practical networks by calculating the
reliability indices. The software module CYMDIST Reliability Assessment Module (RAM) is used for
the simulation and analysis.
Improvement in the reliability performance of power distribution systems
Chandhra Shekar P, Deshpande R A, Sankar V and Manohar P
Reliability assessment is of primary importance in designing and planning distribution systems that
operate in an economical manner with minimal interruption of customer loads. Distributed Generation
(DG) is expected to play an increasing role in emerging power systems because they use different type
of resources and technologies to serve energy to power systems. DG is expected to improve the system
reliability as its backup generation. Since DG units are subject to failures like all other generation units,
the random behavior of these units must be taken into account in the analysis. Existence of DG units
in a distribution system will effect on restoration time of load points. The algorithm for restoration
time assessment of load point is developed when DG unit is installed. In this paper, the reliability
performance of distribution system is analyzed in terms of SAIFI, SAIDI, CAIDI, ASAI, ASUI, ENS
and AENS. The algorithm to calculate the reliability indices for simple 9-bus radial distribution feeder
with and without DG is developed. The improvement in the reliability of the feeder is studied for
different locations of DG with respect to fault point. All the above analysis is carried out by developing
MATLAB software.
Effect of static var compensator on the performance of digital distance relay protection of transmission line
Mohan P Thakre and Vijay S Kale
This paper presents modelling of distance relay with static Var compensator (SVC) and investigates its
impact on the apparent impedance seen by the transmission line distance relay. The functional structure
for SVC built with a Thyristor Controlled Reactor (TCR) and its model are described. The model is
based on representation of the controller as variable susceptance (BSVC) that changes with the firing
angle of the TCR. SVC has a remarkable effect on the apparent impedance seen by the distance relay.
The impact of SVC is more pronounced on the apparent impedance seen by the phase to ground fault.
The mal-operation of the distance protection for the transmission line with SVC at various locations is
studied. It is also shown that the primary winding connection of the interfacing transformer of the SVC
has extraordinary effect on the apparent impedance seen by the relay. The simulation results show that
the under-reaching and over-reaching is more severe with SVC at mid-point of the transmission line.
The impact of SVC on the relay tripping boundaries is also clearly demonstrated.
The Journal of CPRI, Vol. 10, No. 4, December 2014
Gas tightness test methods for gas insulated MV and HV switchgear
Govinda Rao G, Santhosh J and Raghavaiah B V
This paper elucidates the methods used in type testing and factory routine testing to ensure the tightness
of SF6 gas used in Medium Voltage (MV) and High Voltage (HV) switchgear as per the latest IEC
and CIGRE guidelines. Gas insulated MV (>1 kV to ≤52 kV) and HV (>52 kV) switchgear are
frequently being used in electrical power system throughout the world. Mostly, gas insulated MV and
HV switchgear contains SF6 as a pure gas or combined with other gases (i.e.: N2) to form a gas mixture.
Recent times, distinct emphasis is being paid to reducing gas leakage during design, manufacturing
and operation by enhancing gas handling procedures in compliance with Greenhouse gases emission
regulations. Typically the assurance of gas tightness of MV and HV Switchgear shall be defined as the
lowest possible quantity of SF6 released to the atmosphere. Various test methods are used for tightness
test measurement depends upon sensitivity of measurement, quantity and necessity.
Ampacity of bundled PVC house wiring cables in a conduit pipe based on experimental and theoretical considerations
Meena K P, Arunjothi R, Thirumurthy, Raja G K and Nageshwar Rao B
Flexible PVC Cables form the major part of Power distribution system within residential buildings,
industrial buildings, and other commercial institutions. The ampacity of power cable depends upon the
cross sectional area of conductor and the laying and installation of the cable in service. Generally
two or more number of PVC cables are bundled together and inserted as a bundle in a conduit pipe
for connecting to various load points. As the bundling of cables produce more heat than a single PVC
Cable, and dissipation of heat is poor, the ampacity of these cables reduces considerably. Hence the
exact selection of sizes and no. of cables are essential to avoid overheating of those cables and the
resulting fire havocs.
PVC House wiring cables consists of copper conductor extruded with PVC insulation and are installed
generally through a conduit pipe in a bundled manner. The steady state current rating of these cables
depends on the way the heat generated in the cable due to current and the heat transmitted to the cable
surface & then dissipated to the surroundings. The maximum conductor temperature is limited by
the type of insulating material used. In this paper theoretical and experimental results of steady state
ampacity ratings of bundles of house wiring PVC Cables laid in conduit pipes are compared.
The Journal of CPRI, Vol. 10, No. 4, December 2014
Capacitor switching phenomenon for EHV circuit breaker
Santosh Gundap, Manik Hapse, Vishal Vaidya, Snehal Khetre
While, shunt capacitor bank are extensively used to improve loading of the transmission lines as well
as to support system voltages. As these capacitor banks are frequently switched in and out of duty,
enegisation and de-energisation of these bank causes transient voltages are produced. The concerns on
energisation are overvoltage and inrush current, while for de-energisation is restriking.
Switching of capacitor bank, Capacitor bank because of their concentrated capacitance, in contrast with
distributed capacitance, generally draws much more current than unloaded cable or line- in practical
cases up to several hundred of ampere. Switching of Capacitor bank causes a very high rate of rise
of transient recovery voltage across circuit breaker contacts. With improvements in circuit breaker
technology, modern SF6 circuit breakers have been designed with less number of interrupter per pole.
This causes, modern circuit breaker operates with higher voltage stress in the dielectric recovery region
after current interruption. Catastrophic failures of circuit Breaker during shunt reactor and capacitor
bank de-energisation. In those cases, evidence of cumulative re-strikes has been found to be the main
cause of interrupter failure.
Seismic qualification of electrical cabinet
Panneer Selvam R and Ramesh Babu R
Electrical cabinets are widely used in power control systems. Electrical cabinet is housing for many
delicate protection, measuring and control equipments like relays, meters, circuit breakers, logic device,
printed circuit board etc. Seismic load should be one of criteria for selection of electrical enclosures.
Seismically qualified Electrical cabinet ensures proper functioning and safety of equipment installed in
it during and after seismic event. Electrical enclosures should not amplify seismic waves and should
withstand seismic load without undergoing any physical failure. A typical Seismic qualification test
carried out on an electrical enclosure is discussed in this paper.
Switched reluctance drive in industrial application
Yogesh Pahariya, Rakesh Saxena, Bhim Singh
This paper presents the developed switched reluctance motor drive for various applications. The various
applications related to motoring and generating operations are described. The block diagram schemes of
applications are discussed for various control strategy, basic requirements, sensing techniques and torque
speed characteristics. The survey of applications with various manufacturing industries is given. The
performance of controller and control strategies for various applications are compared. The Switched
Reluctance Motor Drive has compared with conventional motors related to various applications and
its suitability.
The Journal of CPRI, Vol. 10, No. 4, December 2014
Estimation of induction motor parameters: an overview
Chaturvedi D K, Mayank Pratap Singh, Md. Sharif Iqbal and Vikas Pratap Singh
The parameters of induction motor depends on various factors such as: machine internal state, machine
ageing, magnetic saturation, operating conditions, the coupling effect between the internal system and
external system. The paper deals with an overview of parameter estimation of three phase induction
motor using different soft computing techniques. The soft computing techniques which are considered
in the paper are fuzzy system, artificial neural network (ANN), Neuro-Fuzzy, genetic algorithms (GA)
and particle swarm optimization (PSO). It is observed that the estimated parameter using soft computing
techniques were much closer to actual value.
Concept of APFC with reference to the energy efficiency
Vishal Singhal
Increasingly, Indian Industry is paying one of the highest power tariffs in the world. Countries in this
club such as Germany and Italy have benefited from Automatic Power Factor control as a competitive
edge. They are already global leaders in Automatic Power Factor Compensation (APFC) Capacitors and
Panels. This paper is aimed at APFC users and takes a hands-on look at extending the lifetime payback
of APFC equipment. The effects of Current, Voltage, Harmonics and Temperature and their interplay
are discussed. These produce degradations in Capacitors and Contactors. Subtle problems go unnoticed
since the equipment is operating silently in a corner, until a catastrophic breakdown occurs. This paper
also discusses practical guidelines for panel designers and users. Peak Inrush Current limiting, forced
cooling, Component specifications, component selection and the role of the APFC controller with its
protective functions are examined.
Effect of ambient temperature on the performance of
power electronic converters
Vani Vijay, Giridhar Kini P, Viswanatha C and Pradeep K
Efficiency of power electronics devices are highly dependent on temperature. Hence temperature
compensation and heat sink design are very important factors in maintaining the performance quality
of power electronic converters. Thus the ambient temperature at which the device is operating also
effects the performance since the heat removal by heat sinks or cooling fans is affected by the ambient
temperature. Here a detailed analysis of the dependency of losses in power electronic switches on the
junction temperature and in turn ambient temperature is presented. A theoretical Analysis of conduction
losses and effect of ambient temperature on it is presented along with a set of experimental results by
analyzing the performance of a 850W Solar PV inverter at various ambient temperatures. The results
are satisfactorily explaining the effect of ambient temperature on converter efficiency.
The Journal of CPRI, Vol. 10, No. 4, December 2014
Novel control strategy of three phase grid tied inverters for power
quality improvement
Chandrasekhar B, Sanjay Lakshminarayanan, Sudhakara Reddy S
Renewable energy sources (RES) are being increasingly connected in distribution systems utilizing
power electronic converters. This paper presents an advanced control strategy for achieving maximum
power quality benefits from the grid interfacing inverters when installed in 3-phase distribution systems.
The grid tie inverter can be utilized as i) Power converter to inject power generated from RES to the
grid and ii) shunt active power filters to compensate current imbalance, load current harmonics, reactive
power demand and load neutral current. All of these functions may be accomplished either individually
or simultaneously. This control concept is clearly explained with MATLAB/SIMULINK simulation
results and THD is less than 5%.
Steady State and transient performance of an inverter based microgrid
Jyothsna T R, Ramya Sree B, Ramya V and Deshpande R A
The analysis of small-signal stability of conventional power systems is well established, but for inverter
based microgrids there is a need to establish how circuit and control features gave rise to particular
oscillatory modes and which of these have poor damping. This paper develops the modeling and
stability analysis of autonomous operation of inverter based microgrids. Each sub-module is modeled
in state-space form and all are combined together on a common reference frame. The model captures
the detail of the control loops of the inverter but not the switching action. Some inverter modes are
found at relatively high frequency and so a full dynamic model of the network (rather than an algebraic
impedance model) is used. The complete models linearized around an operating point and the resulting
system matrix is used to derive the eigenvalues. The eigenvalues (termed “modes”) indicate the frequency
and damping of oscillatory components in the transient response. A sensitivity analysis is also presented
which helps identifying the origin of each of the modes and identifies possible feedback signals for
design of controllers to improve the system stability. With experience it is possible to simplify the
model (reduce the order) if particular modes are not of interest as is the case with synchronous machine
models. Transient stability results have been obtained from a microgrid of three 10-kVA inverters.
Optimal allocation of distributed generator in a radial distribution system
using genetic algorithm and particle swarm optimization
Ashwin N and Veena H S
Many areas in power systems require solving one or more nonlinear optimization problems. Optimal
allocation of distributed generators (DGs) is one of them. This paper proposes two optimization methods
to determine the optimal allocation of distributed generators in radial distribution systems (RDS),
for the purpose of maximizing power loss reduction and improving voltage profile. The proposed
methodology uses Genetic Algorithm (GA) and Particle Swarm Optimization (PSO) to optimize the
objective function and is used to compare it with the analytical method of optimization. The Genetic
Algorithm and Particle Swarm Optimization methods are tested on a standard radial distribution test
systems, which is, IEEE 33 bus RDS using MATLAB R2008b. The results indicate that the optimal
location of the DG is at bus number 6, with a power loss reduction of 83.3 kW.
The Journal of CPRI, Vol. 10, No. 4, December 2014
Design of hybrid power plants for Indian conditions
Siddhartha Bhatt M
This paper presents the basic considerations for design of solar photovoltaic-wind-battery-grid connect
hybrid power plants(HPPs). For ensuring the successful operation of hybrid power plants at low diesel
input and low battery storage requirement, high level of reliability of power supply and reliability of
component are essential. This paper provides factors involved in ensuring that high level of reliability
of components and power availability is fulfilled in the hybrid plants. For both SPV and wind, the
annual energy generation is divided into three regimes: summer, winter and rainy seasons and all these
three have to fulfil the load requirement. It is seen that for 30% solar and 70 % wind generation curve
is the smoothened with less variation.With improved day ahead predictability of both wind and solar
the reliability can be improved considerably.
21. Strength analysis of designed dual axis sun tracker using solid-work software
Neeraj Tiwari, Sanjeev Kumar and Vikas Pratap Singh
This paper describes an approach to the design and implementation of sun tracker stand in PV system
making 120 Volt string. For the strength analysis against wind pressure the PV system with tracker
stand has been implemented in solid work software version SP-13. Another part of this paper is the
comparison of power drawn from The PV system with tracker and without a tracker. The data received
in real experimental setup. We analyzed that the efficiency of PV systems can be increased by 42 %
compared to the static PV system by implementing the tracker techniques in the PV System.
Methods of optimal charging of lead-acid battery for improving its performance and life span
Sudhakar H S, M S Indira, Gujjala B Balaraju and Siddhartha Bhatt M
Battery is an electrochemical energy storage device that converts chemical energy into electricity, by
use of a galvanic cell. The paper presents operation of lead acid battery, its chemical reactions and the
charging methods to improve its performance and life span. The constant current charging mode results
in overcharging of the battery as it is being pushed at full current. The constant voltage charging mode
takes more time to charge the battery fully due to float charge, but the battery will not overcharge
improving the life span. If the lead acid battery is undergoing deep discharge repeatedly then the life
span of the battery will be less than its rated value. The operating temperature also has bearing on the
life span. The paper is also presents the introduction to battery management system (BMS,) which is the
heart of the battery system. The BMS involves a sophisticated supervisory control and data acquisition
system (SCADA) with data management, control, protection and prediction.
The Journal of CPRI, Vol. 10, No. 4, December 2014
Dynamic model of heat ventilation and air conditioning (HVAC) system
Srinivas M and Swarup K S
This paper describes the implementation of SCADA to the HVAC (Heat Ventilation and Air
conditioning) system, which is one among physical systems present in the spent fuel storage facility.
The spent fuel storage facility contains the large number of equipment and control devices to maintain
the facility critical parameters in the permissible limits. The mathematical model of HVAC system is
done to monitor the critical parameters like temperature and humidity with respect to zone conditions.
Over time both the radioactivity and the cooling requirements decrease and these parameters are to
be monitored and controlled. The work projects deals the implementation of SCADA system to the
spent fuel storage facility and monitoring of the critical parameters, the alarms to be generated for the
abnormality situation. The scope of the work covers the SCADA design, modelling and monitoring of
the critical parameters of the HVAC.
The Journal of CPRI, Vol. 11, No. 1, March 2015
THE JOURNAL OF CPRI - Vol. 11, No. 1, March 2015
Fuzzy and PID stabilizers for power systems for small signal
stability enhancement
Noopura S P, Amit Jain and Jayan M V
Small signal stability investigation is important for stability analysis of power systems as a small signal
disturbance could be an initiating event for a large system outage. Fuzzy logic as a novel method for
power system stability has attained wide importance in the recent years. In this paper, stability studies
have been carried out for a single machine infinite bus system which has been modeled according to
the Heffron Philips model. A comparison between the conventional lead-lag, PID and Fuzzy controllers
for damping the system oscillations has also been carried out in this paper. The system is simulated in
MATLABTM Simulink environment and the results have been presented.
A multi objective optimization of transmission expansion planning using genetic algorithm considering reliabilty criteria
Srinivasulu G, Subramanyam B and Surya Kalavathi M
An electric power system plays a crucial role in the economic and social development of a country.
Economic growth in India has spurred the need for more power and hence the infrastructure to transport
the power. Sufficient transmission capacity is very essential in any long-term planning for improving
the availability and supply of power. So Transmission Expansion Planning (TEP) is integral to the
development of a stable and reliable power infrastructure. TEP infuture is a very complex task which
needs a coordinated and analytical analysis of various scenarios and contingencies. In this work we
have implemented a scheme for TEP which factors load growth and considers N-1 contingency.
Both economics and technical considerations are considered in the appraisal of the most desirable
transmission network. A multi objective optimization approach is suggested and the optimization of the
expansion plan is done with the help of Backward Search (BS), Forward Search (FS), Hybrid Search
(HS) and Genetic Algorithm (GA). The TEP is prepared for a 6 Bus-Roy Billinton Test System (RBTS).
Transmission Planning Index (TPI) is introduced to provide a clear indication to the planner about the
choice of the plan. The plans suggested by different optimization algorithms are compared in terms of
performance measures and reliability indices.
The Journal of CPRI, Vol. 11, No. 1, March 2015
A novel distance estimation technique for single line to ground fault in electric distribution network using smart meter
Velhal Geeta Vilas, Avani Pujara, Bakre S M and Muralidhara V
Smart grid concept promises a reliable and efficient supply of electricity. It recognizes the growing
importance of Information and Communication Technologies (ICTs). Monitoring, communication
and controlling are the main systems which can transform the conventional grid into the Smart Grid.
A vivid study of components of the smart grid i.e. smart meter, ICT, Internet Protocol (IP) based
hierarchies, Advanced Metering Infrastructure (AMI) is completed. Smart phone based communication
is drawing attention now days in Smart Grid environment because of the use of Global System for
Mobile Communication (GSM) technology and its real time interactivity. It is based on Client–Server
communication. To initiate a point to point Client Server connection, the transmission control protocol
(TCP) would be used. This paper includes a novice technique for locating single line to ground fault,
and methodology to be applied for it. Fault location is calculated using the real time data obtained from
400 kV Jejuri substation. The length of the Bhigwan – Bilt Graphics line has been measured using
Tauraus kit, and inferences are drawn.
Multi-layered feed-forward back propagation neural network approach for solving short-term thermal unit commitment
Pavan Kumar V and Kulkarni P S
This paper presents an approach for solving the short-term thermal unit commitment (UC) problem
using a multi-layered Feed-forward Back propagation Neural Network (FF-BPNN). The main focus
of the paper is on finding the schedule of committed thermal units within a short computational time
such that the total operating cost is minimized. The proposed method is implemented and tested on a
3-unit and 10-unit systems for a scheduling period of 4-hours and 24-hours respectively in MATLAB
software using the Neural Network toolbox. Comparison of simulation results of the proposed method
with the results of previous published methods shows that the proposed FF-BPNN method provides
better solution with less computational time.
Design and tuning of FACTS stabilizers for dynamic stability
enhancement in multimachine power systems
Senthil Kumar N
This contribution discusses and compares different control techniques for damping undesirable
electromechancial oscillations in power systems by means of power system stabilizer and Series /
Shunt FACTS controllers. The linearized model of the power system is derived with FACTS controllers
and the problem of small signal stability enhancement is formulated as an optimization problem to
maximize the damping ratio of critical electro mechanical modes in the power system. Particle swarm
optimization (PSO) technique is applied to tune the controller parameters of the PSS and FACTS
controllers. The following FACTs controllers are taken for analysis (i) Static Var Compensator (SVC)
(ii) Static Compensator (STATCOM) (iii) Thyristor Controlled Series Capacitor (TCSC) (iv) Unified
Power Flow Controller (UPFC).
The Journal of CPRI, Vol. 11, No. 1, March 2015
A brief review of super-excitation schemes in short-circuit generators
Sreeram V, Gopal D H and Ravindra Mohare M R
Most short circuit generators have static excitation systems to supply field current to the rotor circuit. All
synchronous alternators suffer a reduction in the terminal voltage due to high armature reaction which
is a result of the extremely high magnitude short-circuit currents. The reduction in terminal voltage
will lead to a corresponding reduction in the stator current magnitude. The short-circuit generators are
expected to maintain a constant magnitude of current for specified duration to complete the tests as per
corresponding standards. Hence the short-circuit generators invariably make use of super-excitation to
maintain the required magnitude of short-circuit currents for specified duration. During circuit breaker
testing, it is required to maintain the recovery voltage at pre-fault levels. This requires significant over
excitation of the machine. This paper presents a brief review of the methodology and algorithm of
super-excitation schemesadopted in short circuit testing along with actual data recorded at the High
Power Laboratory at CPRI, Bangalore.
Short time current withstand strength of earth
electrodes-experiences with testing
Maheswara Rao N, Vasudevamurthy B R, Swaraj Kumar Das and Raghavaiah B V
The earth electrode is the main component of the earthing system which is in direct contact with the
ground and thus provides a means of releasing or collecting any earth leakage currents. The electrode
shall have good electrical conductivity and shall not corrode in a wide range of soil conditions. The
design of these electrodes shall be such that they have good current carrying capacity under the earth
fault conditions. This paper describes current withstand capability of these Earth Electrodes during earth
fault conditions. Recent developments in Electrodes and their performance for different fault currents are
given. Failure cases are studied from the laboratory tested Electrodes and appropriate recommendations
were proposed. This can give an insight for estimating fault current withstand capability of a given dia
and material of Electrode. Also different filler materials used for earth electrodes have been discussed.
Stability analysis of multi machine system using
FACTS and renewable energy source
Ravi Babu G and Gowri Manohar T
In this paper, to achieve damping improvement of an offshore wind farm (OWF) fed to a multi-machine
system using a static synchronous compensator (STATCOM) is presented. The operating performance
of the studied OWF is simulated by an equivalent aggregated doubly-fed induction generator (DFIG)
driven by an equivalent aggregated wind turbine (WT) through an equivalent gearbox. A fuzzy logic
controller (FLC) plus adaptive neuro-fuzzy inference system (ANFIS) are designed to achieve adequate
damping characteristics to the dominant modes of the test system under various operating conditions.
A frequency-domain approach based on a linearized system model using root-loci technique and a
time-domain scheme based on a nonlinear system model subject to a three-phase short-circuit fault at
the connected bus are systematically performed to examine the effectiveness of the proposed control
schemes. It can be concluded from the simulated results that the proposed STATCOM integrated with
the FLC plus ANFIS is shown to be superior for improving the stability of the system considered.
The Journal of CPRI, Vol. 11, No. 1, March 2015
9. Performance analysis of current control technique with
RSVPWM and discrete model predictive control technique for
3-Phase voltage source inverters
Lakshmanan S A, Amit Jain and Rajpurohit B S
Voltage Source Inverter (VSI) is one of the essential Power Electronic Converters (PEC) which is used
to utilize the power from the Renewable Energy Sources (RES) in an efficient manner. Some of the
RES produces power in the form of the dc. VSI is used to convert the dc power into ac power. Various
control techniques are implemented to control the inverter circuits. This paper presents a performance
analysis of current control with Revised Space Vector Pulse Width Modulation (RSVPWM) technique
and Discrete Model Predictive Control (DMPC) technique. This analysis is performed on 3-phase VSI.
Basic concepts, control circuits, mathematical models are explained and the control techniques are
simulated using MATLAB / Simulink tool. Simulation results are presented and performances of the
both control techniques are compared.
Transient analysis of cyber-attacks on power SCADA using RTDS
Abhiram Amaraneni, Mahendra Lagineni, Rajesh Kalluri,
Senthilkumar R K and Ganga Prasad G L
Cyber security in the SCADA domain has become one of the major concerns of all the stakeholders in
the energy sector. The SCADA architecture that the power industry adopts is drawing more attention
from a dedicated cyber attacker due to the extent of damage a catastrophe can promise. The usage of
open standard protocols for communication among SCADA components that are not designed with
security in mind is one of those vulnerable areas for any attacker. The SCADA components in the
control region viz., the MTU and the RTU communicate via these insecurely designed open protocols
without any authentication. An attacker can target this communication; launch an attack like the manin-the-middle attack resulting in a disastrous situation. An experiment was conducted at CPRI using
their Real Time Digital Simulator (RTDS) simulating a substation to study the impact of an attack. This
paper brings out the details of the experiment conducted and the results thus obtained.
An intelligent power supply utilization system based on microcontroller
for renewable energy applications
Manish Kumar Ghodki Akhilesh Swarup and Yash Pal
The proposed hardware “an intelligent power supply utilization system based on microcontroller for
renewable energy applications” is a system in which microcontroller is used to automatically control
the power supply of conventional energy source with the help of renewable energy source and power
supply utilized in this way is then used to feed to the load. In this system, supply from the mains is
altered with the help of microcontroller according to the nonlinear supply from solar energy and this
altered power supply of one source is then compensated by another source. This technique will help
to maintain the optional power supply to the load from renewable energy source. The control strategy
for this kind of power supply utilization is written in the assembly language. The system based on this
The Journal of CPRI, Vol. 11, No. 1, March 2015
logic can be used as one of the energy saving option and a tool for promoting and encouraging the
renewable energy sources.
Grid integrated photovoltaic system with active and reactive power control
using fuzzy based controller
Nilesh Shah and Chudamani R
Photovoltaic (PV) panels are costlier and have poor efficiency in energy conversion. Therefore, it is
essential to utilize a PV based system effectively. The characteristics of PV cell are very much nonlinear
that show only one point corresponding to maximum power on P-V curve when the insolation is
uniform. But in partial shading situations, the P-V curve shows many peaks among which only one point
corresponds to the maximum power. In this paper, grid interactive PV system is proposed with active
as well as reactive power control capability even under partial shading conditions using a novel global
peak power point tracking algorithm based on fuzzy logic. The proposed PV system delivers active as
well as reactive power in presence of sunlight. In the absence of sunlight and under low insolation, the
inverter of the PV system provides compensation of load reactive power otherwise inverter remains
unutilized. This improves the utility of PV system and thus enhances the efficiency of the system.
The proposed system is simulated for different partial shading and changing load conditions using
MATLAB/SIMULINKTM. The simulation outcomes authenticate the performance and effectiveness of
the proposed system for active and reactive power flow control with the proposed control approach.
Improved efficiency study of single axis tracking model compared to static photovoltaic system
Neeraj Tiwari, Sanjeev Kumar and Vikas Pratap Singh
This paper presents the performance study of single axis tracking system compared static PV system. To
increase the efficiency of PV System. We designed a simple and cost effective 170W sun tracking system
for the experiment. The whole experimental setup has been implemented in SimulinkTM platform for the
analysis of improved efficiency. The objective of this paper to optimize the solar energy receivers. In
this paper, a Simulink model of the static PV system and Tracking PV system has been presented. In
the fabrication of real sun tracker system we used a 24 VDC motor and a simple LDR based control
circuit for the tracking purpose. The block diagram with detailed description and performance of the
tracking system are presented.
A study of boost converter with solar photovoltaic system for maximum
energy efficiency
Sudhakar H S, Indira M S, Gujjala B Balaraju and Siddhartha Bhatt M
Performance of a SPV system is dependent on temperature, array configuration, solar insolation, shading
etc. The conversion of solar energy using SPV modules,change in insolation conditions which severely
affect the efficiency and output power of the modules. Improvement in the efficiency of conversion
of solar energy can be done by tracking the maximum power point of a PV module. Various types of
MPPT charge controllers are available in the market. A dc-dc converter is an important component of
a SPV system as it acts as an interface between the load and the SPV module. These dc-dc converters
enhance the performance of the MPPT algorithms leading to an improvement in the overall efficiency
The Journal of CPRI, Vol. 11, No. 1, March 2015
of the SPV system. This paper presents the modeling and simulation of one diode equivalent circuit of
solar photovoltaic module using MATLAB/SIMULINKTM along with the boost converter which gives
an efficiency of 93.29%.
3-D space vector modulation algorithm for multilevel inverters in abc coordinates for solar PV applications
Aparna Paulose Vani Vijay Reeba S V and Neha Adhikari
Solar PV based Power generation is gaining importance in the present scenario of energy crisis. Precise
control of Solar PV inverter is a very important factor deciding the efficiency and performance of Solar
PV sources. Space Vector Modulation (SVM) technique is widely used for pulse width modulation in
inverters, especially for power supplies for obtaining improved sine wave output. It is based on the
representation of the three phase quantities as vectors in a two-dimensional using α and β co-ordinates.
Here, a new three–dimensional (3-D) space vector algorithm in a-b-c co-ordinates for multilevel
inverters is presented, which is based on the 3-Dimensional geometry of the vectors. This method
calculates the on-state duration of switching vector without involving trigonometric functions, look-up
tables or coordinate system transformation. Hence the computational complexity is very less compared
to other algorithms. The proposed scheme is explained for a multilevel inverter and simulation results
are presented with comparison of performance of a two level inverter and a three level inverter using
this technique. The results shows that the algorithm can be applied for higher level inverter so that it
operates at reduced Total Harmonic distortion.
16. Design of two-stage soft-switched module inverter for photovoltaic applications
Elanchezhian P, Kumar Chinnaiyan V and Sudhir Kumar R
In this paper two stage boost photovoltaic micro inverter system using maximum power point tracking
is presented. First the photovoltaic module is analyzed using SIMULINK software. The main aim of the
paper is the boost converter with microinverter to be used along with a Maximum Power Point Tracking
control mechanism. The MPPT is responsible for extracting the maximum possible power from the
photovoltaic and feed it to the load via the boost converter which is used to steps up the voltage to
required magnitude. Both the boost converter, and the solar cell are modelledusing Sim Power System
blocks. Here the voltage source inverter is cascaded and it injects sinusoidal current to the grid. The
dynamic stiffness are obtained when load or solar insolation changing rapidly. This paper investigates
in the detail concept of Maximum PowerPoint Tracking (MPPT) which significantly increases the
efficiency of the solar photovoltaic system.
Multi input DC- DC converters for hybrid renewable
energy systems-an overview
Chandrasekhar B Sanjay Lakshminarayanan and Sudhir Kumar R
Single input DC-DC converters can be successfully replaced by a single, multiple input DC-DC
converter. The structure of Multiple-Input Converter (MIC) is simpler compared to the use of several
single input converters for each source. Using input renewable energy sources like photovoltaic (PV)
The Journal of CPRI, Vol. 11, No. 1, March 2015
source, wind source and fuel cell, etc, MIC can deliver power either simultaneously from all of the
input sources to the load or individually. MICs reduce the system size and cost by reducing the number
of components. This paper presents integrated Buck, Boost, Buck-Boost multi input DC-DC converters
circuit configurations, theoretical aspects, their operational principles, merits and demerits.
Optimal sizing of battery storage system by utilizing the reactive power
capability in wind based distribution network
Sangeetha R S, James Ranjith Kumar R, Amit Jain, Sreejaya P and Jayan M V
Day by day energy crisis and environmental issues are increasing. The most effective solution for these
issues is the use of renewable energy sources (wind, solar etc.) in distribution networks (DN). However
these have some disadvantages and one among them is uncertainty in nature. So it’s difficult to utilize
the full potential of renewable energy sources. By using battery storage systems (BSSs) this problem
can be avoided. In this paper, an optimal power flow (OPF) is formulated, for the spilled energy
calculation. For maximum utilization of spilled energy BSS needs to be properly sized and here, it is
done by a nonlinear programming (NLP) technique. Also, maximum potential of BSSs can be exploited
by providing both active and reactive power from BSS to the network. The methodology is applied
to a 47 bus Indian distribution system and results demonstrate that, there is a significant reduction in
energy supplied by the grid and losses due to the integration of BSS. In this work it is assumed that
wind generators are integrated into the network.
Wind load assessment on guyed steel tower with three different codes
Veerendra Kumar Shukla and Selvaraj M
Guyed towers are special structures widely used in communication industry as antenna supporting
structures. A guyed tower is a nonlinear structural system in which the mast, consisting of single beamcolumn or multiple members are supported elastically at various points along its height by inclined
pretension cables with their ends anchored to the ground. In this paper the wind loads on 120 m tall
guyed tower are estimated with three different codes of practices, Indian Code, American Code and
British Code. The estimated wind loads are compared and brought out in this paper.
Optimization of ambient energy component in large mixed
mode central AC plants
Siddhartha Bhatt M
This paper presents the study of energy efficiency improvements of central air conditioners (AC)
through the optimal integration of natural air ventilation functions. There is potential for energy saving
through the shifting to mixed mode air conditioning invoking the ambient energy for cooling. An
optimization study shows that up to an ambient temperature of 22 ˚C, passive cooling can be used and
beyond that temperature active cooling is required. Simulation of energy consumption for air condition
has been undertaken in 5 major cities of India, viz., Bengaluru, New Delhi, Mumbai, Kolkata and
Chennai. The energy efficiency specified as per ECBC (energy conservation building code of India)
is 80-90 kWh/m2/year for AC and can only be reduced through passive cooling components. Results
indicate that it is possible to reduce the energy consumption by almost 50 % through the use of natural
air ventilation cooling.
The Journal of CPRI, Vol. 11, No. 1, March 2015
Effect of ethanol on the performance and emission characteristics
of biodiesel fuelled diesel engine
Ashok Kumar K, Kapilan N and Nagaraja K V
The fossil fuel resources are depleting day –by-day and there is an increasing demand of fuels which
increases environmental pollution. This problem leads to stringent emission regulations which pose a
challenge to science and technology to find out environmental friendly fuels. Among the renewable
energy sources, biodiesel derived from vegetable oils and fats are considered as an immediate substitute
for the fossil diesel in the I.C.Engines. In India, biodiesel derived from non-edible oils such as honge,
jatropha, neem, mahua, simarouba etc are considered as an alternative fuels to the fossil diesel, as there
is demand for the edible oils. In this work, biodiesel was produced from non-edible honge oil by two
step transesterification. The honge biodiesel properties were determined and most of the fuel properties
are similar to the fossil diesel. However, Biodiesel has high viscosity, lower volatility which affects
the atomization and spray formation. In this regard, the alcohol such as ethanol which is having lower
flash & fire point, high flammability and is produced from renewable energy sources was used as good
additive for biodiesel to improve its fuel properties. In this work, the engine tests were conducted on
a single cylinder, four-stroke direct injection diesel engine using diesel, honge biodiesel and ethanol
blended bio-diesel in four different compositions by volume ranging from 5% to 20% . The Engine
performance and emission characteristics were analysed by varying the load. From the engine test
results, it was observed that, the BE5 i.e. 5% ethanol in biodiesel results in better performance than
other blends and neat biodiesel operation.
A case study of high temperature reheater boiler tube failure
Arvind Kumar
Several investigations on the failure of boiler tubes of thermal power plant have been carried out. This
paper presents the failure analysis of a reheater tube of 210 MW thermal power plant. The reheater
tube got damaged after service exposure a life of 1,65,900 hrs. The failed tube has a slit type opening
with minor circumferential expansion at the rupture section. Scale was observed on the inside and
outside surface of the tube. The scale formed on the outside and in-side surface of the tube was analysed
through EDX and XRD to know the constituents of the scale and in evaluating the cause of failure of
the tube. The tube was observed through its cross-sectional for the wall thinning. The area around the
failed reheater tube sample was prepared and studied for structural degradation; hardness mapping was
also carried out on the tube to find the cause of failure.
The Journal of CPRI, Vol. 11, No. 1, March 2015
Fly ash cenospheres – A resourceful material for engineering applications.
Ananda Kumar M G, Shekhar Kumar M, Suryanarayana K, Vynatheya S,
Venkatesh T R, Seetharamu S, Jagannath Nayak
In India, about 60% of the total power generation comes from thermal power stations operating on
fossil fuels like coal and lignite [1]. Presently about 400 million tons of coal and lignite is consumed
annually for power generation. Typically, Indian coals have an average ash content of about 45%,
thereby leading to generation of around 180 million tons of ash annually as an industrial by product.
Out of the total ash generated, 70 % of this ash comprises of fly ash and the remaining are bottom ash,
economizer ash, air-preheater ash, etc. Presently, dry fly ash is being utilized in a big way in value
added products like bricks, blocks, pavers, etc., while bulk volumes of fly ash is consumed in blended
cement manufacture, different types of concrete, construction of dams, roads, river embankments, etc.
Fly ash also contains about 1.0 % hollow particles called as ‘Cenospheres’ generated during combustion
of the pulverized coal at high temperatures in the thermal power plant boilers. Cenospheres is a useful
by-product of coal combustion which can be harvested from the ash ponds or by any other methods such
as tribo-electric separation, slurry precipitation, pond skimming etc., from fly ash. Fly ash cenospheres
are unique in the way that they possess excellent properties such as lightweight, low density, nonmetallic, high melting points. These unique properties make cenospheres a prospective raw material
to produce value added products for use in engineering applications. The paper discusses the work
carried out at Central Power Research Institute on cenospheres characterization and development of
value added products for various applications.
The Journal of CPRI, Vol. 11, No. 2, June 2015
THE JOURNAL OF CPRI - Vol. 11, No. 2, June 2015
Strategies for detection of out-of-step phenomenon for
power system protection and control
Dijin Divakaran and Amit Jain
Power systems, nowadays, are subjected to severe oscillations during the post disturbance span of time
because of its operation at very narrow stability margins. Out-of-step condition is a consequence of
transient instability and protection against out-of-step condition is a major issue for the power industry.
In order to operate a system safely and to protect from the damages caused to system components such
as generators, transmission lines and switching equipment, proper out-of-step detection and necessary
protective action has to be provided. This paper explains the various out-of-step detection strategies
which can be augmented to the numerical relaying algorithms, their computational simplicity and
reliability and also discusses the issues and challenges related to implementation.
Power system stability : Mode identification in the power system
oscillations using wide area measurement systems
Matta Srinu Babu, Ajay Shankar and Seethalekshmi K
In the past few decades power system oscillation damping remains as one of the major concerns for
secure and reliable operation of power systems. In response to a continual increase in demand, power
systems are driven closer to their limits, especially those of transmission capacity. As such, enhancing
the transfer capability, while keeping the system stable, is one of the main goals for system operators.
When we transfer a bulk amount of power over a long distance through relatively weak tie lines
and high gain exciters then problem of small signal oscillation occurs. These oscillations have also
resulted into instability and blackouts in the power system. In this instability problem there are different
frequency components which are known as modes. This paper work consist of identification of low
frequency components i.e. local area and inter area modes of oscillations in two area power system
and also in IEEE 39 bus system.
Loss reduction and reliability optimization in electrical distribution systems
using network reconfiguration
Ravi Kumar D and Sankar V
Network reconfigurationis an operation strategy, which alters the topological structure of the distribution
feeders by rearranging the status of switches in order to obtain an optimal configuration, minimise
system losses and to improve reliability. In this paper, an approach using Distribution Load Flow(DLF)
solution and a reconfiguration algorithm that enhances voltage profile, reliability and voltage stability
index besides minimising losses is developed. The proposed algorithm has been implemented on33 bus
Radial Distribution System (RDS) in the MATLABTM environment.
The Journal of CPRI, Vol. 11, No. 2, June 2015
DC fault analysis in voltage source converter based HVDC link
Karishma S K B, Sreedevi J, Noor Cheshma P and Sarada K
The use of voltage source converter (VSC) based HVDC transmission for the interconnection of various
power networks is increasing day by day. However, VSCs susceptibility to DC faults, particularly the
potential damage caused to the converter switches due to overcurrent, is an issue. The fault clearing
must be done very rapidly, to limit the effect of the fault on neighboring networks. This paper analyses
the two terminal behavior of a VSC- based HVDC system under DC fault condition. In this work,
HVDC link is connected between the systems of two different frequencies. Simulations are carried
out in RSCAD/RTDSTM software and the performance of the system is analyzed for DC faults and the
results are presented.
Multi-layered feed-forward back propagation neural network approach for solving short-term thermal unit commitment
Pavan Kumar V and Kulkarni P S
This paper presents an approach for solving the short-term thermal unit commitment (UC) problem
using a multi-layered Feed-forward Back propagation Neural Network (FF-BPNN). The main focus of
the paper is on finding the schedule of committed thermal units within a short computational timesuch
that the total operating cost is minimized. The proposed method is implemented and tested on a 3-unit
and 10-unit systems for a scheduling period of 4-hours and 24-hours respectively in MATLABTM
software using the Neural Network toolbox. Comparison of simulation results of the proposed method
with the results of previous published methods shows that the proposed FF-BPNN method provides
better solution with less computational time.
Intelligent distance to over current relay coordination in
sub-transmission networks
Manohar Singh, Manikya Sastry and Lalitha SVNL
Sub-transmission power networks are primarily protected by distance relays and over current relays
are used as backup relay due to their poor operational speed. Coordination of distance to over current
relays is achieved in this research paper by optimally selecting the over current relay parameters which
constitutes relay time-inverse characteristics and relay parameters and zone-2 setting of distance relays.
Solving such type of combine distance to over current relay coordination problems is tedious job using
the conventional optimization methods. Therefore an evolutionally based optimization techniques is
applied in this research paper which selects the optimal over current relay parameters, user defined time
inverse relay characteristics and zone-2 settings of the distance relays.
The Journal of CPRI, Vol. 11, No. 2, June 2015
Power loss reduction and voltage stability enhancement
by optimal location of UPFC
Siva Subramanyam Reddy R and Gowri Manohar T
The power system is a very complex system. The considerable components of power system are
voltage, power flows real and reactive power losses. These components are controlled by compensating
the system. The system can be compensated by the various types of devices such as static capacitors,
synchronous condensers etc. But the devices which are mentioned are not providing the flexible control
of the power system components. The majority of the losses are shared by the transmission system.
By controlling the parameters at transmission, the total system is controlled. So the devices with the
combination of power electronic devices provide the flexible control on the transmission system of
the power system parameters which are called FACTS devices. This paper proposed the combined
series-shunt compensation FACTS device called UPFC. This paper mainly concentrated on the suitable
placement of the UPFC FACTS device for Loss reduction and enhancement of voltage profile of the
power system using Fast Voltage Stability Index (FVSI).
Optimal DSTATCOM placement in radial distribution
system using fuzzy-ANFIS
Ramesh Babu U, Vijay Kumar Reddy V and Tarakalani S
Paper aim is to obtain voltage control with optimal DSTATCOM placement to decrease the total cost
of voltage regulators and losses. This algorithm makes the initial selection, installations and buck-boost
setting of the DSTATCOM which provides a smooth voltage profile along the network. It is also used
to obtain the minimum number of the initially selected DSTACOM, by moving them in such way as
to control the network voltage at the minimum possible cost. Software using MATLABTM has been
developed and implemented using back track algorithm, fuzzy logic and ANFIS (Artificial Neuro Fuzzy
Inference system) results are compared.
Cryogenic cooling aspects of hts power cables - A review
Ipsita Das, Nageshwar Rao B, Sundara Rajan J, Seetharamu S and V V Rao
HTS (High Temperature Superconducting) cable has the ability of transmitting electrical power over
long distances in an economical way, with improved stability and reliability. HTS Cable also provides
a compact and low-loss transmission power line, in comparison with the conventional cable made out
of copper or aluminium. The use of HTS tapes facilitates the cable operations with liquid nitrogen
cooling system. A wide variety of HTS Cables with various cooling arrangements have been designed
and developed. Their performance has been tested to obtain various thermo-hydaraulic and electrical
data by installing the cables of different lengths in transmission and distribution networks. This paper
reviews the cryogenic cooling aspects of previous and ongoing projects on superconducting cables for
electrical power transmission around the world.
The Journal of CPRI, Vol. 11, No. 2, June 2015
Design of high temperature induction motor for application in
sodium cooled fast reactor control system
Nashine B K, Rajendra Prasad, Vijay Sharma and B P C Rao
Prototype Fast Breeder Reactor (PFBR) employs induction motors of various power ratings in high
temperature ambient and sometimes corrosive atmosphere. Safe operation of the reactor depends on
robustness and reliability of induction motors in its critical components. Safety related systems such
as shutdown and online inspection systems, utilize induction motors as actuators in their mechanisms.
Since external cooling is not permitted in control and inspection motors, special design of motors is
required to withstand high temperatures. This paper deals with design, analysis, fabrication and testing
of a compact 50 W, three phase induction motor, suitable for operating up to 250 °C ambient with
winding temperature withstand capability up to 550°C. The designed motor was analyzed with two
dimensional Finite Element Model (FEM) code FEMM to study the torque slip characteristics and
magnetic flux density patterns in stator and rotor.
On line gnn based induction motor parameter estimation
Chaturvedi D K, Mayank Pratap Singh, Md. Sharif Iqbal and Vikas Pratap Singh
The induction motor is commonly used in industries due to its rugged construction and almost no
maintenance. To precisely control the induction motor, accurate estimation of parameters is required.
Artificial Neural Network (ANN) is used in the past for parameter estimation. The conventional ANN
has its own problems such as learning issues, unknown size of ANN and its connections, etc. To
overcome some of its problems generalized neural network is used in this paper. The GNN is trained to
estimate parameters of three phase induction motor. Experimental setup is developed in DEI, which is
consisting of a 415 V, 3Φ squirrel cage induction motor, data acquisition system and on-line parameter
On line cooling system fault detection in induction motor
Chaturvedi D K, Md. Sharif Iqbal, Mayank Pratap Singh and Vikas Pratap Singh
Induction motors are popularly used as an electric drives are the critical component in industrial
systems. Most of the faults in induction motor are because of excessive heat generated in the machine.
In the industrial application a large rating of induction motors are used which produce a significant
heat. The heat is produced in the motor due to the different losses accumulated in the machine. Hence
a healthy cooling system is always required to dissipate the heat and maintain the motor temperature
within acceptable limits. This paper deals with the problem occurred specially in the cooling system
under different operating conditions and investigate them. The on-line information is gathered from
the machine about temperature, current and vibration signatures at different operating condition and
the health of the cooling system is analyzed. Soft computing techniques are utilized for this purpose.
The Journal of CPRI, Vol. 11, No. 2, June 2015
On line cooling system fault detection in induction motor
Chaturvedi D K, Md. Sharif Iqbal, Mayank Pratap Singh and Vikas Pratap Singh
Induction motors are popularly used as an electric drives are the critical component in industrial
systems. Most of the faults in induction motor are because of excessive heat generated in the machine.
In the industrial application a large rating of induction motors are used which produce a significant
heat. The heat is produced in the motor due to the different losses accumulated in the machine. Hence
a healthy cooling system is always required to dissipate the heat and maintain the motor temperature
within acceptable limits. This paper deals with the problem occurred specially in the cooling system
under different operating conditions and investigate them. The on-line information is gathered from
the machine about temperature, current and vibration signatures at different operating condition and
the health of the cooling system is analyzed. Soft computing techniques are utilized for this purpose.
Knockdown analysis of the performance of solar photovoltaic plants
Siddhartha Bhatt M
This paper presents an efficiency map of a solar photovoltaic (SPV) plant through knock down analysis
for the three major cell types monocrystalline silicon (C-Si), multicrystalline (M-Si) and amorphous
silicon (A-Si). The highest efficiency achievable by a SPV cell is the Shockley-Queisser (SQ) limit
which is the ultimate efficiency. When it comes to computing the working cell efficiency which can
be treated as the SQ nominal conditions (after considering the cell losses) there is a drop. Moving up
the organizational level, while at the module level, there is a further drop in the overall efficiency by
2-3 % points between the cell and the module. Further drop is seen when computing under Standard
test conditions (STC) conditions and (PTC conditions PV-USA industrial test conditions). The STC
module efficiency is taken as the reference or base condition for the SPV plant design. From the
module to the array there is yet a drop of 3-4 % points. The performance drop of the plant from the
STC conditions to the actually achieved conditions can be represented by the performance ratio (PR)
which considers the stochastic efficiency of the plant site. The PR excludes excludes auxiliary power
(2-4 % of the generated power), losses in battery (~20 %) due to storage component (if storage is
present) and loss of energy generated due to non-availability of the grid (for grid tied systems). The
stochastic incident radiation loss (~16-37 %) is already accounted in the PR. Automation helps to a
large extent in tracking the component efficiencies and correcting the losses.
Photovoltaic Emulator
Shashank V, Srinivas Reddy T and Kulkarni P S
In order to facilitate the testing of PV systems, PV panels are required and it is necessary to connect
them in different configurations to get the required output voltage and power. The output of PV panels
depends on environmental factors like insolation, temperature, inclination of the panel, partial shading,
etc. hence it is difficult to maintain and reproduce the same characteristics of PV panel. Therefore
PV emulator is required to maintain and reproduce the same characteristics irrespective of weather
conditions to facilitate the testing of PV systems. The aim of this paper is to design a controlled DCDC converter which acts as PV emulator.
The Journal of CPRI, Vol. 11, No. 2, June 2015
Design and testing of a novel single-stage half-bridge
AC-DC converter for battery charging
Nandagopal J L, Lekshmi R Chandran Remya R and Vani Vijay
AC-DC converters are used in most of the electrical utility applications especially in battery charging.
Here, a novel topology for single-stage bridgeless ac-dc converter is presented which can give an
isolated output voltage and input power factor correction. The input current to an ac-dc converter
is rich in low order harmonics and so the total harmonic distortion is high and input power factor
is poor. Hence Power Factor Correction (PFC) schemes have been implemented. The effectiveness
of the converter is tested and verified in PSIMTM simulation software and in experimental hardware
prototype. This topology is found to have reduced losses and better power factor correction compared
to the single-stage PFC ac to dc converters with full-bridge diode rectifier. This topology is suitable
for battery charging application with reduced losses and better power quality.
Influence of irradiance, ambient conditions and AC power output on
micro inverter temperature-overview
Elanchezhian P, Kumar Chinnaiyan V, Sudhir Kumar R and Karpagam J
Solar energy is one of the cleanest and reliable sources of renewable energy on earth. Conventionally,
extraction of solar power for electricity generation was limited to PV farms, however lately distributed
generation form of solar power has emerged in the form of residential and commercial Grid Tied
micro-inverters. Micro inverters temperature is strongly correlated with ambient temperature and PV
module temperature, and moderately correlated with irradiance and AC power. Ambient temperature
is the influencing factor under conditions of low irradiance in morning hours, when the irradiance is
below 60 W/m2. Noon time data analysis reveals that the micro inverters thermal behaviour is more
strongly influenced by PV module temperature than AC power. In this paper review about electrical
circuit topology and Influence of irradiance, AC power, ambient temperature on PV module and micro
inverter are discussed.
An integrated double input DC- DC buck converter in hybrid energy system
Chandrasekhar B, Sanjay Lakshminarayanan and Sudhir Kumar R
Integration of more than one energy source depends on the power electronic converters is an interesting
and challenging task for researchers. In this paper, integrated double input DC to DC converter for low
voltage energy source applications is explained. Integrated buck converter which can step down the
input voltage according to output voltage required at the load end. The converter is able to integrate
different voltages of various energy sources such as solar photovoltaic, wind energy system, fuel cell
and diesel etc. of relatively low voltage. The converter is designed considering double input, in which
same or different type of two inputs can be used individually or simultaneously. Modes of operation of
converter are described in detail, closed loop simulation with a PI controller using MATLAB/SimulinkTM
results are presented in detail.
The Journal of CPRI, Vol. 11, No. 2, June 2015
Studies on the performance and emission characteristics of Mahua
oil fuelled low heat rejection diesel engine
Ashok Kumar K, Chethan Kumar N and Kapilan N
The world energy reserves are depleting day-by-day and the demand is increasing. This leads to search
for suitable renewable alternative fuels. Among the available alternative fuels, biodiesel can be used as
an immediate substitute for the diesel engine. However, the biodiesel fuelled diesel engine gives lower
brake thermal efficiency due to higher viscosity and lower volatility of the biodiesel. Hence, in this work,
an attempt was made to increase the performance of the biodiesel fuelled engine using ceramic coating
on the engine combustion chamber components. In this experimental study, engine components such
as cylinder head, piston, exhaust and inlet valves were coated with Nickel Chromium (NiCr) alloy and
Yttria Stabilized zirconia (Y2O3 –ZrO2) of thickness 250 µm using plasma spray coating. Since mahua
oil has significant potential for the biodiesel production, it was used for the biodiesel production. In this
work, the engine tests were conducted on a single cylinder four stroke direct injection diesel engineand
different blends were used as the fuels. The engine performance and emission characteristics were
analysed by varying the load under both coated and uncoated conditions of the engine and results were
compared with neat diesel. From the engine test results, it was observed that the engine performance
with biodiesel blends such as B10 and B20, was increased from 3 to 7% depends upon the load on the
engine with thermal barrier coating as compared to the normal engine without coating.
Damage assessment of attemperator of thermal power plant boilers
Dhiraj M Gourkhede
Due to rapid growth and development and the demand for power, has pushed steam plant design into
new territories of temperature and thermal cycling. Coupled with this has been the tendency for plant
suppliers to buy rather than design critical items of equipment in the hope of minimising exposure to the
consequences of malfunction however, this has seen an upsurge of trouble in several areas –particularly
with attemperator. Although simple in concept, attemperator can cause serious problems if details of
their design are not properly considered, and/or if they are not properly applied to the systems they are
to serve.
This paper presents by using optical fiber based video imaging technique to identify the affected regions
in the attemperator which causes the malfunctioning of the boiler which may resulting catastrophical
failure and damaging its components. This will result in reduced frequency of forced outages of the
plant which in turn lead to substantial savings to the utility.

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