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The CECRE: Making renewable energy technologies compatible with the security of the system - María Sánchez (REE)
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The CECRE: Making renewable energy technologies compatible with the security technologies compatible with the security
of the system
June 2013
Who is Red Eléctrica?
Red Eléctrica de España (REE) is the Spanish transmission system operator (TSO)
System Operation:
❑ Operate the grid & coordinates its uses with the generation facilities in order to ensure the security
and continuity of the electricity supply.
Transmission (Since 2007 as exclusive transmission company):
❑ The development and the maintenance of the transmission facilities
❑ Provide maximum service reliability
2
❑ ~ 41,000 km of lines and 78,000 MW of transforming capacity
Transmission Grid End 2012
Main magnitudes (SPPS) REE
Lines400 kV [km ct] 20104
≤≤≤≤ 220 kV [km ct] 21124
Substations
≤≤≤≤ 220 & 400 kV [nº bays] 5053
Transformers [MVA] 78050
� System Overview
� Installed capacity in Spain today
� Issues and solutions integrating RE nowadays
� Demand coverage
Outline
3
� Distributed Generation (Observability/Controllabilit y)
� Grid constrains (RdT/RdD)
� Behavior facing disturbances (Voltage dips)
� Power balance feasibility and RES courtailments
� Voltage control
� Impact of forecast errors(SIPREOLICO/SIPRESOLAR)
� CECRE: Control Centre for Renewable Energies
� Conclusions
� System Overview
� Installed capacity in Spain today
� Issues and solutions integrating RE nowadays
� Demand coverage
Outline
4
� Distributed Generation (Observability/Controllabilit y)
� Grid constrains (RdT/RdD)
� Behavior facing disturbances (Voltage dips)
� Power balance feasibility and RES courtailments
� Voltage control
� Impact of forecast errors(SIPREOLICO/SIPRESOLAR)
� CECRE: Control Centre for Renewable Energies
� Conclusions
Spanish Electrical System
GeneratorsInternational Exchanges · REESpecial Regime
Transmission network· REE System Operator· REE TSO (foreign)
Ancilliary services bids
5
Daily and Intradaily
Market
Daily and Intradaily
Market
Demand bids
Energy flows
Communication
Market Operator· OMEL
Distribution companies
Red de dis tribución< 132 kV
S ubes taciónde dis tribución
Qualified consumers
Outages
Ancillary ServicesAncillary Services
Consumers with/without
last resort tariff
Suppliers Last resort suppliers Demand bids
Daily load demand
Maximum demand:
41 318 MW 13:26 h 19/07/2010
Maximum demand:
45 450 MW 18:53 h 17/12/2007
Winter load demand record Summer load demand record
6
Big gap between peak hours demand
and off- peak hours demand
• Spanish maximun peak demand: 45 GW
• Spanish minimum off-peak demand : 18 GW.
Influential factors in load demand
Temperatura Mínima
1.9 ºC24000
28000
32000
Temperatura Máxima
34.1 ºC 31.2 ºC
29.3 ºC
28.7 ºC24000
28000
32000
❑ Temperature
38.000
30.000
34.000
36.000
28.000
32.000
Temperature Mínimum Temperature maximum
7
8.3 ºC
20000 20000
Nubosidad
21000
25000
29000
❑ Cloudiness
Puente Fiesta Postfestivo
10000
13000
16000
19000
22000
25000
28000
L M X
❑ Holidays
26.000 24.000
38.000
26.000
30.000
34.000
38.000
26.000
30.000
34.000
36.000
32.000
28.000
Long weekend: work day -bank holiday-work day
World Cup 2010 final in South Africa (11th July 2010)Influential factors: special events.
32000
33000
34000
20:30 h home matchs
23:00 h final matchs
8
27000
28000
29000
30000
31000
32000
MW
HORA 21:15 h first half
22:15 h second half
800-1.400
600-1.100
1.500-2.400
Transmission capabilities of interconnections(I)
9
1.500-2.400
1.500-2.400
600 900
http://www.ree.es/operacion/capacidades.asp
•In specific situations, usually linked to unavailability of network elements of the transport capacity values can occur below the ranges presented.Not considered these values by its low frequency and representativeness.
� System Overview
� Installed capacity in Spain today
� Issues and solutions integrating RE nowadays
� Demand coverage
Outline
10
� Distributed Generation (Observability/Controllabilit y)
� Grid constrains (RdT/RdD)
� Behavior facing disturbances (Voltage dips)
� Power balance feasibility and RES courtailments
� Voltage control
� Impact of forecast errors(SIPREOLICO/SIPRESOLAR)
� CECRE: Control Centre for Renewable Energies
� Conclusions
Installed capacity june 2013
Hydro-power17,31% Thermical Renewable
0,64% CHP &Other RE7,26%
Solar PV
Solar CSP2,05%
Special regime hydro2,04%
Technology MW %Combined cycles 24947 24.9Hydro-power 17303 17.3Coal 10740 10.7
11
Combined cycles24,96%
Coal10,75%
Fuel-Gas0,51%
Nuclear7,58%
Wind22,59%
Solar PV4,32%
Coal 10740 10.7Nuclear 7572 7.6Fuel-Gas 506 0.5Total (ordinary regime) 61068 61.0Wind 22668 22.6CHP &Other RE 7252 7.2Solar PV 4429 4.4Special regime hydro 2039 2.0Solar CSP 2050 2.0Thermical Renewable 639 0.6Total (special regime) 39077 39.0
Total 100145
251.901 GWh = 174.144 Net Ordinary Regime+ 102.428 Net Special Regime
-11.206 International exchanges-3.215 Hydro-pump storage- 570 Baleares Interconnection
Demand supply 2012
12
Special Regulation RegimeRenewable:
MinihydroBiomassWindIndustrial wasteUrban wasteSolar
Non Renewable:CogenerationCoalFuel - Gas oilRefinery gasNatural gas
Coal; 12,6% Coal national (RD
134/2010); 7,7%
Combined cycle; 14,8%
Fuel-
Gas;
0,0%Nuclear; 23,2%
Small Hydro; 1,8%
Hydro-power; 7,6%
Solar CSP; 1,4%
Solar PV; 3,2%
Wind; 19,1%
CHP Renewable; 1,9% CHP non RES; 13,3%
∑Energy without emissions CO 2 ≈ 58,2% ∑Renewable Energy ≈ 35%
Installed capacity evolution
13
� System Overview
� Installed capacity in Spain today
� Issues and solutions integrating RE nowadays
1.- Demand coverage
Outline
14
2.- Distributed Generation (Observability/Controllabi lity)
3.- Grid constrains (RdT/RdD)
4.- Behavior facing disturbances (Voltage dips)
5.- Power balance feasibility and RES courtailments
6.- Voltage control
7.- Impact of forecast errors(SIPREOLICO/SIPRESOLAR)
� CECRE: Control Centre for Renewable Energies
� Conclusions
1.- Demand coverage
� Big difference between peak hours demand and off- peak hoursdemand during the day
� No possibility to storage big quantity of electrical energy meansGeneration must adapt to demand in each moment
� Flexibility of each plant to adapt their production to the demandnecessities is mainly determined by technology facilities
15
Continuous manageable generation actions are needed in order to maintain system equilibrium
necessities is mainly determined by technology facilities
� RES has priority of dispatch� RES production depends on their primary energy availability
It is required plants that can adapt their production to the demand necessities: manageable generation
Demand coverage: Wind Generation in year 2012 (I)
Maximum coverage 2012 (24/09/2012): 64% wind production = 13285 MW
16
Minimum coverage 2012(11/09/2012): <1% wind production = 81 MW
Very variable production output
Historical maximum wind production ( 06/02/13 at 15:49 h): 17056 MW
Winter
PV power plants:
WindRES
CC Hydro
Demand coverage: Solar photovoltaic
0
5
10
15
20
25
30
35
40
45
50
7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00
MW
Hour of the day November 21st 2010
Plant 1 30 MW Plant 2 13 MW Plant 3 7 MW
17
Winter
Sumer
PV power plants:
CC Hydro
Wind RES
CC Hydro
Plant 1 30 MW Plant 2 13 MW Plant 3 7 MW
Plant 4 22 MW Plant 5 48 MW Sum 120 MW
0
10
20
30
40
50
60
70
80
90
100
6:00 7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00
MW
Hour of the day October 20th 2010
Plant 1 30 MW Plant 2 13 MW Plant 3 7 MW
Plant 4 22 MW Plant 5 48 MW Sum 120 MW
CSP power plants:
WindRES
Demand coverage: Solar thermoelectric (I)
18
Winter
Sumer
CSP power plants:
CC Hydro
Wind RES
CC Hydro
Example of the needed flexibility Maximum demand 36 319 MW
Generation mix during off-peak
Downward tertiary reserve exhausted in hours 3:00-9:30 and
15:00-18:00 h
19
5 combined cycle units during off-
peak hoursMinimum demand
20 638 MW
30 combined cycle units during peak
hours
2.- Distributed generation:Lack of observability and controllability
� Connection points are far from consumption.
� More than 2000 RE facilities , each belonging to different companies withdifferent policies on operation and maintenance.
� Slow contact in case of emergency reductions, outages or transmissionassets maintenance.
20
assets maintenance.
� If required actions take too much time, risks are higher . Then stricterlimitations must be applied and have to be planned further in advance, sohigher reductions to RES production have to be established by the TSO.
Solved by grouping facilities in control centers with real-ti me contact with the System Operator through the CECRE.
Observability, why?
OBSERVABILITYReal time
measurements
Production
forecastHot reserve
evaluationAvoiding
demand
forecast errors
21
� Observability is required to have real time information of theproduction of the renewable energy facilities.
� This information is used to make reliable production forecastsfor this type of installations.
� Renewable forecasts are a basic tool for hot reserve evaluation .Its accuracy affects the required levels of reserve and helpsdispatching manageable generation to counteract renewable andnon manageable variability.
� Receiving the real time measurements of all the generationfacilities allow the TSO to distinguish between generation anddemand , avoiding demand forecast errors as well.
Dispatching
manageable
generation
COUNTERACT
RENEWABLE
VARIABILITY
Observability: And if not, what?
Without a reliable
forecast
Demand forecast
errors
22
Increasing
Uncertainties
Reducing the
Security of the
system
Increasing the
required level
of reserves
Reducing RE
production
3.- Grid constrains
Depending on the generation scenario and the grid situation there are significant changes in the use of lines .
� Transmission grid/Distribution grid maintenance works
23
� Transmission grid/Distribution grid maintenance works� Grid elements unavailability due to breakdowns
It is necessary to reduce renewable non manageable generation to maintain security system or grid elements
� Influence of renewable energy integration in power flows
November 3 rd 2011 November 6 th 2011 November 7 th 2011
Grid constrains
24
Heavy flows from the North-West to the center and East.Low hydro and CC.
Heavy flows from the Eastto the center and North.Low hydro and CC.
Heavy flows from the Eastand South-West to thecenter and South. Highhydro and CC.
4.- Behavior facing disturbances
Technological characteristics (power electronics) of some RES facilities can cause:
� Wind and solar photovoltaic generation tripping due to voltage dips� Wind generation tripping due to their over-speed protection
25
Increase of installed RES power with fault-ride-thr ough capabilities and system security
� Demand coverage:� Demand is given at a certain moment, until relevant demand side management
takes place, generation must adapt to demand to maintain system equilibrium.
� Adequacy to system demand profiles.
� Variability and predictability
5.- Power balance feasibility and RES curtailments
26
The combination of these two factors along with the behavior and uncertainty of the
demand contribute to situations with balance feasib ility difficulties due to lack of
downward reserve.
� Variability and predictability� Variability influences the rest of the electric system that must compensate such
variations to keep the system balanced.
� Predicting this variability and awareness of uncertainties crucial for efficientoperation.
Generation mix during off-peak hours
Balance feasibility during off-peak hours (I)
Maximum demand:39 183 MW
Downward tertiary reserve exhausted in hours 2:00-6:00
27
Minimum demand:23 653 MW
27 combined cycle units during peak hours
Balance feasibility during off-peak hours (II)
Lower production on peak hours
Wind Combined cycle
28
1 combined cycle unit during off-peak hours
High production during off-peak hours
6.- Voltage control
� Parameter that determines system quality.
� Conventional generation, through reactive power injection/absorption, play an essential roll in continuous system voltage control at the substation level.
�Nowadays, RES generators only maintain power factor.
29
Continuous voltage control through the CECRE also for RES generation with P>10 MW.
7.- Impact of forecast errors (SIPREOLICO/SIPRESOLAR)
� Forecast can mitigate the effects of renewable energies variability in System Operation, but errors must be taken into account and additional reserves must be provided to overcome them.
� Larger forecast errors imply more provision of reserves increasing system
30
� Larger forecast errors imply more provision of reserves increasing system costs
REE has developed its own prediction for wind generation (SIPREOLICO)
and for solar generation (SIPRESOLAR )
7800
8200
8600
Impact of forecast errors on system operation
Wind Solar
� Increase of 586 MW in 30 min. Gradient: 1172 MW/h
� Decrease of 1110 MW in 1 h 25 min. Gradient: -785 MW/h
� Decrease of 400 MW in 1 h
� Solar gradients are smaller than wind gradients due to the
fact that wind total installed capacity is quiet higher than
solar one. But also relevant.
31
5800
6200
6600
7000
7400
7800
At present wind downward/upward ramps may reach
±1500 MWh.
Renewable production depends on weather conditions, so less wind or more clouds mean great production gradients. So it is necessary to check the instantaneous need for manageable generat ion in order to size reserves . Generation RES forecast becomes crucial for system balancing.
RES forecasts available to the CECRE
Wind: SIPREOLICO Solar: SIPRESOLAR
� Aggregated national hourly forecast up to 10 days in advance
� Detailed hourly forecasts up to 48 hours in advance
� Developed in MATLAB environment
� Statistical method: based on self-adaptive time series
� Two different forecast for CSP and PV.
� Aggregated national hourly forecast up to 10 days in advance
� Detailed hourly forecasts up to 48 hours in advance
Based on artificial neural network..
32
� Statistical method: based on self-adaptive time series
� Probabilistic wind power forecast: confidence intervals
� Based on artificial neural network..
� Probabilistic wind power forecast: confidence intervals
� On the morning of Sunday November 2nd at 8:00 h with one of the lowest demands ofthe year (~20 000 MW), wind prediction error hit 3 200 MW.
� Increase in error from 5:00 to 7:00 h too fast to have time to shut down thermal plants.
� Spanish system ran out of downward reserves very rapidly and the only solution to
Exhaustion of downward reserve due to wind forecast errors Wind reduction instructions, November 2nd 2008
33
� Spanish system ran out of downward reserves very rapidly and the only solution tobalance the system was to decrease wind production from 7:22 to 9:30 h.
� January 23rd and 24th 2009: Storm Klaus. Winds up to 220 km/h hit the Iberianpeninsula.
� Most turbines in the north of Spain shut down due to their over-speed protection.
Difference between real and forecasted wind production was greater than 6 000 MW on
Exhaustion of upward reserve due to wind generation tripping
Wind reduction instructions, January 23 rd and 24 th 2009
34
� Difference between real and forecasted wind production was greater than 6 000 MW onsome hours, but since demands were low and thermal plants were connected in realtime due to alert situation there was enough upward reserve to deal with these errors.
� System Overview
� Installed capacity in Spain today
� Issues and solutions integrating RE nowadays
� Demand coverage
Outline
35
� Distributed Generation (Observability/Controllabilit y)
� Grid constrains (RdT/RdD)
� Behavior facing disturbances (Voltage dips)
� Power balance feasibility and RES courtailments
� Voltage control
� Impact of forecast errors(SIPREOLICO/SIPRESOLAR)
� CECRE: Control Centre for Renewable Energies
� Conclusions
� Target: achieve a greater level of integration for renewable energy sources withoutcompromising system security
� Main function: Organise special regime electric production according to the needs of theelectric system.
Control Centre for Renewable Energies (CECRE)
36
� System Overview
� Installed capacity in Spain today
� Issues and solutions integrating RE nowadays
� Demand coverage
Outline
37
� Distributed Generation (Observability/Controllabilit y)
� Grid constrains (RdT/RdD)
� Behavior facing disturbances (Voltage dips)
� Power balance feasibility and RES courtailments
� Voltage control
� Impact of forecast errors(SIPREOLICO/SIPRESOLAR)
� CECRE: Control Centre for Renewable Energies
� Conclusions
Conclusions
� Integrating non manageable generation is a challenging tas k: Low availability, production notcorrelated with consumption, lack of firmness of generation programs and power balance difficulties.
� Although these, CECRE and the RESCC have helped to reach a high penetration of special regimegeneration in the System making these technologies compatible with security of supply.
� Wind forecast has been improving in the last years , being now a basic tool for hot reserveevaluation. Its accuracy for time scopes from 5 hours to 24 hours in advance affect required levels of
38
evaluation. Its accuracy for time scopes from 5 hours to 24 hours in advance affect required levels ofreserve and helps dispatching manageable generation to counteract wind fluctuations.
� CSP plants can adapt their production to the demand necessit ies , even more if they can storageheat into salts. But it is necessary to pass the power controllability tests carry out by the SO.
� Complying with the new RD 1565/2010 will let the TSO to receive the real time measurementsachieving visibility and controllability of the solar PV generation.
� In addition, if facilities are grouped in control centers with real-time contact with the SystemOperator through the CECRE, implies that curtailments take less time to be done so less strictlimitations could be planned and placed, increasing RES production and installation.