doubling the load transfer capacity – ACCC conductor

A P P L I C AT I O N C A S E
doubling the load transfer capacity – ACCC conductor
In 2007, Elia was informed that an industrial plant was going to commission a new 400MVA production
unit and deliver power to the Belgian transmission network by 2010. A small coal fired production unit
some 20 km further down was going to be shut down around the same time. Load flow studies examining
system reliability at N-1 showed that a 20km long double-circuit 150 kV connection would be overloaded
under certain conditions.
The two circuits were strung with ACSR 298mm² conductors having a diameter of 22.4 mm and had a
maximum load transfer capability of 162 MVA each. The maximum operating temperature was 75 °C as
specified by Belgian legislation. The challenge Elia faced was to increase the load capacity of each circuit
from 162 MVA to 360 MVA without important reinforcement of the tower-foundation system and with
minimal environmental impact. Each circuit had to be upgraded while the second stayed in operation.
The solution
All technical solutions were considered before deciding that reconductoring was the best option. Circuit
reconductoring did not require the existing towers and foundations to be reinforced and it was the only
solution that enabled Elia to complete the project within a reasonable time-scale.
The sag of the new conductor at its maximum operating temperature could not exceed the sag of the
existing ACSR 298mm² at 75°C. The outer diameter of the new conductor and the forces on the existing
towers had to be less or equal than with the ACSR 298mm² conductor. At 75°C the load transfer capacity
of the new conductor had to be some 22% higher than previously. Several new or existing technologies
were examined to check whether they could meet the requirements: ACSS, GZTACSR, ACCR and the
most recent technology, ACCC.
After comparing all solutions on the table, Elia went for the ACCC Lisbon 325mm², which offered several
advantages:
•
doubled load transfer capacity with a conductor of the same size
Lamifil nv
Frederic Sheidlaan
B-2620 Hemiksem, Belgium
Tel. +32 (0)3 870 06 11
Fax +32 (0)3 870 06 74
www.lamifil.be
VAT - BE - 0422 050 265
RPR Antwerp
FORTIS Bank: (BE49) 220-0035440-71 BIC : GEBABEBB
ING Bank: (BE62) 320-0027054-61 BIC : BBRUBEBB
A P P L I C AT I O N C A S E
•
limited expenditure for reinforcements
•
previous
present
ACSR 298mm²
ACCC Lisbon
conductor
22,4mm
21,78mm
diameter
662A
1380A
no significant modifications to the towers,
lower sag helps reducing magnetic field
level at the annual mean current
•
reduced time for reconductoring existing
nominal current
double circuit vertical
super-bundle
low-reactance
circuit configuration
circuits resulting in the lowest overall cost
compared to other technical solutions.
•
75°C
180°C
max. operating temperature
the ACCC Lisbon 325mm² has the lowest
150kV
nominal voltage
line losses
20km
circuit length
Replacing the ACSR 298mm² conductor with ACCC Lisbon 325mm² conductor for this line doubled the
ampacity and should save an estimated 64,500 MWh of losses over a 30 year economic life. It should
also reduce generation capacity requirements by 600kW and save the emission of over 40,000 metric
tons of carbon dioxide over that 30 year period.
During installation, Lamifil and CTC Cable monitored the conductor stringing
procedure, the installation of the accessories and controlled the quality of the
work. All conductor compressions were subject to a visual inspection by Elia
Grid Services prior to commissioning and immediately after commissioning; the
transmission line was checked with thermo-vision. To secure the knowledge
and expertise with respect to ACCC technology, Elia trained a full crew of their
Grid Services - Power Links division.
The possibility to make compressions on dead-end clamps on the towers with
a light 60-ton press was considered to be a major advantage for safety and
comfortable working conditions.
Conclusion
Elia, the Belgian TSO successfully completed its first project involving ACCC
conductor. The installation of some 125km of ACCC conductor ran smoothly
and was completed ahead of schedule. The 150kV double circuit transmission
line is back into normal operation since the end of November 2009, and is now
offering ample current carrying capacity at a temperature up to 75°C and has a
long term spare capacity for working under N-1 conditions.
Lamifil nv
Frederic Sheidlaan
B-2620 Hemiksem, Belgium
Tel. +32 (0)3 870 06 11
Fax +32 (0)3 870 06 74
www.lamifil.be
VAT - BE - 0422 050 265
RPR Antwerp
FORTIS Bank: (BE49) 220-0035440-71 BIC : GEBABEBB
ING Bank: (BE62) 320-0027054-61 BIC : BBRUBEBB