DE ESPAÑA - Ofgem

EXPERIENCE WITH RAPID GROWTH OF WIND GENERATION IN SPAIN

24th of May of 2004

D E ESPA Ñ AR ED ELÉCT RIC A

Experience with rapid growth of wind generation in Spain2

RED ELÉCTRICA DE ESPAÑA

Wind generation installed (SPPS)

SPPS: Spanish Peninsular Power System

0

1000

2000

3000

4000

5000

6000

1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

MW

0%

5%

10%

15%

20%

25%

30%

Installed power Installed power/Peak load



%

Relative importance of wind power

70

0

10

20

30

40

50

60

Denmark

Switzerl

and

Austria

Holland

Belgium

Sweden

Finland

German

yUE+N

+CH

UENorw

ayGree

cePortu

galIta

liaFran

ceSpain

U.K.

Maximum interconnection capacity / Peak load

14,3%

15,8%

Installed wind power / Peak

load

33.771

75.800

Peak load (MW)

Wind production /

Annual demand

Wind production / Total production

Annual demand (TWh)

Wind production

(GWh)

Installed wind power

(MW)

Year 2002

4,30%4,26%210,39.0394.830Spain

3,31%3,27%498,616.50012.001Germany



Impact of wind farms on the electric power system

❑ Local: ❍ Modification of power flows and voltages❍ Influence over protection schemes and contribution to fault current❍ Power quality:

HarmonicsFlicker

❍ Need for new installations and reinforcements – not meshed substations

❑ Global:❍ Transient stability❍ Voltage control and reactive power❍ Frequency regulation❍ Influence in the generation program



Fault ride-through capability of wind farms❑ Disconnection of wind

generation due to correctly cleared short-circuits in 2004❍ 17th & 18th of January.

Several single-phase two-phase and three-phase faults, cleared with definitive trips and trips with re-closing. Lost up to 465 MW of wind power.

❍ 26th of February. Two-phase fault in a 400 kV busbar. Lost aprox. 600 MW of wind power.

❍ 1st of April. Two three-phase faults in 400 kV network. 500 MW of wind power disconnected.

❍ 18th of April. Three-phase fault in 400 kV line close to substation. Lost aprox. 400 MW.

Incidencia en Ls-220 kV Hernani-Itxaso, 1 y 2. a 01:01 h. (b)

Incidencia en L-220 kV Güeñes-La jara-Ayala-Poza de la Sal (c)y AT2 400/220 kV Güenes.

Incidencias en L-400 kV Barcina-ItxasoY L-400 kV Grijota-Vitoria (d).

Incidencia en L-400 kV Hernani-Itxaso y AT1 400/220 kV Güeñes. (e)

Incidencias en Ls-132 kV Ormaiztegui-Hernani, 1 y 2 (f).

Incidencias en L-220 kV Mercedes-Puentelarra,AT1 220/132 kV Puentelarra y L-220 kV Garoña-Puentelarra (g).



System security. Transient stability❑ During correctly cleared short-circuits occurred in the transmission

network, big amounts of wind generation are disconnected from the system, due to too sensitive protection systems❍ Ministerial order of 5th September 1985 – “Three instantaneous minimum voltage

protection systems must be installed between phases, adjusted at 0,85*Um, to detect performance in island”

❍ Self-protection of wind generators – Some technologies are not able to stay coupled when voltage goes under 0,9 pu due to their internal electronic components.

1 sec.

500 ms

500 ms

Delay of the protection

5.000 MW

3.000 MWOff-peak load

10.000 MWPeak load

Wind production admissibleDemand

Installed power13.000 MW



Production control❑ Special demand situations – Deep off-peak scenarios in which conditions are

more extreme than in the studies used to determine maximum wind production admissible (1st of January of 2004)



Influence of wind generation in system operation. Operation program

❑ Generation program❍ Very affected by the precision of wind production forecast

❑ Technical restrictions❍ In occasions it is not possible to maintain the system variables within acceptable values applying technical restrictions only to ordinary generation

❑ Unbalance❍ More energy managed

Bad precision in wind production forecast forces a bigger use of operation markets



❑ Primary regulation❑ Secondary regulation❑ Tertiary regulation❑ Voltage control

Influence of wind generation in system operation.Ancillary services

Variability in wind generation forces a bigger use of ancillary services

Wind generation replaces ordinary generation and reduces the resources

available for regulation and voltage control



Excessive use of secondary regulation

Producción eólica PBF (MW)Eólica real estimada (MW)Eólica real telemedida (MW)

1300 MW

1000 MW



❑ Not meshed substations

❑ System restoration❍ Wind generation does not have black start capability

❍ Difficulties to know its state during restoration

❑ Production vs. Installed power

Influence of wind generation in system security

0

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80

0% 20% 40% 60% 80% 100%

Probability of exceding the production

Perc

enta

ge o

f gen

erat

ion

exce

eded



Power quality

❑ The affection of wind generation to power quality is limited bythe connection criteria

❍ Evacuated power ≤ 50% of the evacuation capacity in the connection bus:

❍ Capacity of the lines❍ Capacity of the transformers

❍ Evacuated power ≤ 5% of the short-circuit power in the connection bus

❑ Ministerial Order in draft, with emission limits for all major disturbances:

❍ Harmonics❍ Flicker❍ Unbalance



Conclusions: Red Electrica’s proposal (I)❑ In order to integrate a big amount of wind generation in the Spanish

electric system, maintaining the security and quality conditions, it is needed that these installations meet some requirements:❍ Capability to not disconnect during short-circuits (not consuming active or

reactive power during the disturbance). Do not disconnect in the gray area of the figure.

Voltage

(pu)

1

0,2

0,5 1 Time (sec.)

Beginning of the

disturbance

0,80,95 pu

0 15

Clearance of the

fault

Duration of the fault



Conclusions: Red Electrica’s proposal (II)

❍ Participation in solving technical restrictions, specially in critical stability situations.

❍ Integration in dispatching offices that can accept Red Eléctrica’sorders to meet the requirement mentioned above.

❍ Participation in voltage regulation.❍ Forecast of the production.❍ Evacuation in existing substations.❍ Adequacy to these requirements of the existing wind farms.

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