the cecre: making renewable energy technologies compatible with the security of the system - maría...

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



� Demand coverage

Outline

4





� Voltage control



� 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)

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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



� Demand coverage

Outline

10





� Voltage control



� 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

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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

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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



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)


� 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

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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

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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

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Winter

Sumer

PV power plants:

CC Hydro

Wind RES

CC Hydro


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 4 22 MW Plant 5 48 MW Sum 120 MW

CSP power plants:

WindRES

Demand coverage: Solar thermoelectric (I)

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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

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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.

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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

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� 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

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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

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� 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

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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

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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

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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

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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

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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.

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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

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� 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.

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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..

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� 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

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� 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

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� 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



� Demand coverage

Outline

35





� Voltage control



� 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



� Demand coverage

Outline

37





� Voltage control



� 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

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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.

Thanks for your attention!

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María Sánchez [email protected]

the cecre: making renewable energy technologies compatible with the security of the system - maría...

Technology

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total special regime

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