Participation to auxiliary services

Load:
Participation to auxiliary services
WG System operations
April 2011, Carton Filip
Agenda
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Introduction Auxiliary services
Goal of this meeting
R1 – load
R2 – load
Free bids
Conclusion - Discussion
Way forward
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Introduction auxiliary services
Entso-e has defined clear guidelines and control mechanisms in her POLICY 1
“Load-frequency control and performance” that TSO must adhere to
 GOAL = FREQUENCY CONTROL : maintain the frequency within UCTE as close
as possible to 50 Hz = system frequency f0
 Definition of 3 type of reserves:
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3 Types of reserves; characteristics
Auxiliary service
Response time
Characteristics
Primary control
+++
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R1
Automatic
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Decentralized
(local)
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Automatic
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Centralized
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Tertiary control
+
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R3
Manual
activation by
operator
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Secondary control
R2
Centralized
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Must be activated within seconds to maintain a continuous balance between
GENERATION and consumption (DEMAND) for the complete SYNCHRONOUS AREA.
The primary reserve power remains activated until secondary reserve power in the
imbalanced CONTROl AREA has taken over.
Limited volumes which are determined at ento-e level
Until so far only performed by production units in operation.
Must be a activated in a few minutes until a quarter to relieve the primary control.
The secondary reserve power remains activated until tertiary reserve power or ARP
corrective actions have taken over.
Slightly larger volumes than the primary reserve power. Volumes are recommended by
entso-e, but determined by individual control areas.
Until so far only performed by flexible production units in operation.
Participants should have appropriate control and communication equipment because
the secondary control signal (Delta P) is calculated by Elia and sent to participants for
execution.
Is activated manually in order to relieve secondary control and remains activated until
ARP corrective actions have taken over.
Higher volumes that are determined by each control area
The tertiary reserves are set out: power generating plants, power available from
interruptible customers and emergency contract with neighboring TSO
=> R3 already exists as a product for customers = ICH
3 Types of reserves; volumes
Volumes contracted in 2011
2011
Primary control
106 MW
Secondary control
Average 137 MW with a minimum of 100 MW
Tertiary control
660 MW from which
400 MW is contracted on production units
261 MW is contracted with industrial customers
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Scope of today
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R1
Yes
R2
Yes (high level only)
R3
Exists as ICH => NO
CIPU
Free bids for industrial customers?
(high level only)
MVAR
n/a => No
Black start
n/a => No
Losses
n/a => No
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PRIMARY CONTROL
R1
frequency
production
load ?
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R1: Entso-e Policy 1
Objective: to maintain a balance between GENERATION and consumption (DEMAND) within
the SYNCHRONOUS AREA, using “primary controllers”
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mandatory common reserve of 3000MW for the whole synchronous area, distribution
of this volume over all TSO’s pro rata produced. energy of Y-2
must react within seconds ! (0  30 secs) and be able to remain active for at least
15mins.
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within 15secs: 50% of R1 delivered, within 30secs: 100% R1 delivery
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full reaction on a frequency deviation of 200 mHz : 49,8 Hz - 50,2 Hz
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“steady state frequency” should always be inside +/- 180 mHz
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instantaneous frequency should always be between 49.2 Hz and 50.8 Hz
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insensitivity of controllers of ± 10mHz = “dead band” of undisturbed operation
(continuous frequency variations)
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from 49 Hz and below load shedding will (have to) be performed
In undisturbed situation, primary controller must be available without interruption,
this means regardless of production unit or customer commitment.
Primary control must be proportionally adjusted to follow frequency deviations.
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R1 – Time based deployment
Locally activated by the frequency
+106 MW
49,99Hz
49,8Hz
50Hz
-106 MW
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50,01Hz
50,2Hz
f
R1 usage in Elia zone
Area’s with low
solicitation of
primary reserves
% of time between 20mHz band =
% of time between 50mHz band =
% of time between 100mHz band =
% of time between 150mHz band =
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66,57911172
96,76781821
99,88196771
99,99999834
AS-IS
∆P
∑ of individual plants to
meet contractual
obligations
Contracted R1+
Deratings
∆fqs1
f<fs
f>fs
Plev
Individual power plants,
each with his own
droop
Contracted R1-
For a freq. dev plev is calculated
= - λ0 * (Pb1[Leverancier, Periode] * fqs1 + Pb2[Leverancier, Periode] * fqs2)
For the basic service Pb1 = Pb2.
λ0 = 15000 [MW/Hz]/3000 [MW] = 5 [1/Hz].
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# options at first sight:
1. Symmetrical/continuous R1-load?
-200mHz
+200mHz
Possible for load to offer a
symmetrical/continuous service
in line with entso-e obligations?
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Plev = -5 * ∆f * contracted R1 (+and-)
# options at first sight:
2. Asymmetrical/continuous R1-load?
∆P
Possible for load to offer a
asymmetrical/continuous service
in line with entso-e obligations?:
Contracted R1+
+200mHz
Plev = -5 * ∆f * contracted R1 (+ only)
f>fs
-200mHz
f<fs
Contracted R1-
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# options at first sight:
3. Asymmetrical/discontinuous R1-load?
-200mHz
+200mHz
Possible for load to offer a
Asymmetrical/discontinuous
service in line with entso-e
obligations?
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Feasibility?
When looking in to the participation of load as provider of R1 some issues need to be
answered:
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Compliancy with policy 1?
• Policy 1 allows load to participate as R1 reserve, however no distinction is made
with regard to the performance compared to power plants.
- => R1 load should be equally performing!
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Feasibility for industrial customers:
• Discontinuous R1 load seems fairly comparable with the ICH product except that R1
has to be available 100% of time + it must be proportionally adjusted to follow
frequency deviations + ICH has a limited number of activations + activation is
required within 15-30 seconds…
• Continuous R1-load seems less obvious from a technical point of view?
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Feasibility for power plants:
• In case asymmetric R1 load would be sourced, unless other options could be found,
power plants should need to make up for the additional R1 volume that is required
for the frequency area f>fs. Not only this must be technically possible, cost
reduction should cover at least for the cost of R1-load.
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Contractual implications (producers)  New contracts (industrial customers)
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Compliance wrt entso-e obligations?
Some articles need specific attention:
Equal performance
for load and
generators
UFLS will respond in
case of f-drop.
However,
when freq picks up
again => delay for
load to restore?
=> Avoid non-compliancy!
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Feasibility for industrial customers:
Discontinuous asymmetric product (UFLS):
• This seems similar to ICH => technically feasible?
• Availability could be an issue since R1 must be available @ 100%
• Ramping back up after being shed = 30min up till several hours?!
• Tests have been performed by a client, showing and increasing #activation over the last years?
• Asymmetry must be made up (or be proven) elsewhere…
Continuous asymmetric or symmetric
• Has been proposed by a client in 2008… but investigations slowed down due to economical crisis.
• Other client stated it would require quite some analysis to develop a continuous regulator for load.
• If not symmetrical, asymmetry must be made up (or be proven) elsewhere…
General
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considerations:
Reliability? (cfr economical crisis, plant shut-down, etc…)
Impact on ICH? (no overlaps with other products should be allowed)
Impact on ARP-contract for inclusion in imbalance tariff.
Nomination of R1 by customers? = new
Pricing: overall package “R1-load + R1 power plants” < AS-IS?
Contracting:
- Define service + remuneration
- Control of availability must be covered
- Control of activation must be covered
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Feasibility for the Power Producer
In order to enable participation of Load in R1, R1 volumes contracted with power
producers should be:
• Diminished (symmetric R1 Load product)
- foreseen by contract => covered.
• Made asymmetric (asymmetric R1 Load product)
- Proposition that would cover discontinuous R1-load was made by Elia
for 2012 contracts.
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Feasibility for producers?
2012 contracts should allow:
∆P
Discontineous R1Load
Contracted R1+
Less volume for R1+
on power plants
Formula for Plev to be
modified for f<fs
1) Less derating
2) Less units
participating
(change droop)
f<fs
f>fs
Contracted R1-
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Volumes for R1unchanged
Conclusion R1 / discussion
Taking previous into account
Discontinuous asymmetric product (UFLS):
• Seems technically the least complicated even though some important challenges remain to be
covered: proportionality, load pick-up, reliability, etc…
• If the cost reduction for asymmetric R1 on power plants wouldn’t make up for the cost of sourcing
this with customers… there would be no economical driver to go forward.
Continuous asymmetric
• Technical challenge for industrial customers?
• Not clear if power plants are technically capable to make up for the asymmetry (not = as UFLS)
• Cost issue could also surface here.
Continuous symmetric
• Technical challenge for industrial customers?
• A cost reduction for R1, contracted on power plants is certain in this case (less volume)
Remarks?
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R2-Load … or free “load” bids
In the past focus of load participation (except for ICH) had been on primary
control:
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2008: detailed feasibility study was performed with some industrial clients,
focused on R1. Those didn’t lead to a product… amongst others due to the
economical crisis?
03/2009: SC UCTE approved adapted Policy 1
- Policy 1 now allows load to participate to R1 if this has the same
performance as power plants.
12/2010: Investigation of R1-load concept is re-launched.
However, recent questions made it clear that there could be an interest for R2-load or
even free “load” bids.
=> An open discussion is useful to determine which product would offer the most added
value, not only for industrial customers and Elia, but for the community.
There for, a high level presentation of those is also made hereafter.
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SECONDARY CONTROL
R2
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R2: Entso-e Policy 1
SECONDARY CONTROL maintains a balance between GENERATION and consumption
(DEMAND) within each CONTROL AREA / BLOCK as well as the SYSTEM FREQUENCY
within the SYNCHRONOUS AREA, taking into account the CONTROL PROGRAM
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SECONDARY CONTROL makes use of a centralized (remember = local for R1)
AUTOMATIC GENERATION CONTROL, modifying the active power set points /
adjustments of GENERATION SETS in the time-frame of seconds to typically 15
minutes. (remember = 15-30 seconds for R1)
Reacts in compensation of and after primary control and must remain active until
balance of control area is restored.
Recommendation of reserve volume by entso-e but each TSO estimates R2 to fulfill
a minimum quality of control
Individual action by each TSO
Triple objective:
Exchanges between control areas should return to programmed values to
avoid free energy transfers between areas
Border flows should return to normal to avoid additional congestion
R1 must be freed up to be available for next outage
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R2: Entso-e Policy 1
250MW recommended
Avg 137MW
contracted
TRUMPET CURVE
Loss of
production is
compensated
by R1.
Frequency
stabilizes at
f2<<<f0
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Within 15min
restoration of f0
after loss of
production>
1000MW
Gradual recovery
of frequency
towards f0 as R2
takes over from
R1 after 30secs
Control loop in our SCADA (as-is):
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R2 usage in Elia zone
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percentage of time between -100 en +100 =
percentage of time between -137 en +137 =
percentage of time > 0 =
percentage of time < 0 =
73,258%
95,473%
51,699%
44,217%
Controls
R2 activation control
Gap
Tolerance
limits
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As-is => Worth investigating R2-load?
15 minutes
R2 provided by # of power
plants…
15 minutes
Is it worth investigating if
industrial customers could provide
a part of this service?
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Conclusion R2?
In fact R2 is fairly comparable with R1 except:
• activation is centralized => a signal is sent by Elia to the participants.
• An average + a minimum value is contracted => required availability is not 100%
When looking in to the participation of load as provider of R2 some issues need to be
answered:
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Compliancy with policy 1?
• Requirements for R2 are less strict then for R1: >> activation time, availability, etc
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Feasibility for industrial customers:
• If continuous R1 would be feasible … then continuous R2 should be as well.
• However, R2 activation is larger then R1 …
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Feasibility for power plants:
• In case symmetric R2 load would be sourced => no feasibility issues here.
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New contracts (industrial customers): reservation; availability & activation controls
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Impact on ARP perimeter
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Free “load” bids?
The idea come from free CIPU bids.
What are CIPU bids?
• all remaining power on production units must be offered
to Elia for real-time activation.
• No reservation price.
• Activation prices are based on free prices.
• Up and Down Regulation is possible within the
operational limits of the power plant.
• Manually activated (for a minimum of 15min)
• No guaranteed volumes.
A similar product could be created for load…
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Free “load” bids?
What would be the difference with ICH?:
• For ICH a reservation price is paid, for free bids this
wouldn’t be the case.
• ICH activation prices are fixed, for free bids the
activation price would be free.
• The number of ICH activations is contractually limited,
for free bids the number of activations would depend on
the number of times your free bid is the most interesting
one.
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Overall conclusion + next steps
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Opportunities could exist for load to participate in R1, R2 or free
bids.
Before exploring further in detail it should be clear that:
• sufficient stakeholders are interested to go forward with the
design of a product, and which one.
• there is a cost driver for the chosen product.
Next steps?:
1. Confirmation by industrial customers on which product offers
the best opportunities. Via a federation?
2. Creation of a task force assembling impacted stakeholders
(incl producers for asymmetric products)
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Questions
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