Powering Europe - European Wind Energy Association

alancingdemand,conventionalgenerationandwindpower
fiGURE 2: EstiMatEs of thE inCREasE in REsERVE CaPaCity REqUiREMEnt DUE to winD PowER
combination. Additional flexibility from conventional
units is especially critical in situations of low load and
high wind [Ummels, 2008] because in such situations
the thermal plant may have to be ramped up fast because
of sudden drops in wind power generation. More
generally, increased wind power will mean conventional
thermal units will have to be operated in a more flexible
manner than if there were no wind energy.
2.3 Short-term forecasting
to support system balancing
Wind power forecasting has become essential for operating
systems with a significant share of wind power.
Forecast systems are used by various parties, including
network operators, energy traders and wind plant
operators. The main benefits are reduced costs and
improved system security. Forecasting enables wind
power to be traded and integrated in the scheduling
70
Increase as % of wind capacity
20%
18%
16%
14%
12%
10%
8%
6%
4%
2%
0%
Increase in reserve requirement
5% 10% -15% 20% 25% 30%
Wind penetration [% of gross demand]
UK 2007 distributed wind
Dena Germany
Finland 2004
Minnesota 2004
Nordic 2004
California US
Sweden 1 hour
Sweden 4 hours
Ireland 1 hour
Ireland 4 hours
the Dena study takes into account the day-ahead uncertainty (for up and down reserves separately), whereas the Uk
study takes into account the variability of wind four hours ahead. in Minnesota and California, day-ahead uncertainty
has been included in the estimate. for the others the effect of variations during the operating hour is considered.
for ireland and sweden the four hour ahead uncertainty has been evaluated separately [holttinen, 2009].
system, which eventually ensures that demand and
power supply are balanced and makes use of the most
cost-effective generation sources.
In regions with a high level of penetration – which include
regions in Spain, Germany, Denmark and Ireland
– wind farm operators routinely forecast output from
their wind farms. These forecasts are used by system
operators to schedule the operations of other plants,
and for trading purposes. Areas of power system operation
where system operators specifically benefit from
wind power forecasts include:
• Routine forecasts: increasing the confidence levels
• Forecasting in critical periods, e.g. times of maximum
load (including ramps)
• Forecasting of significant aggregated wind power
fluctuations (ramps)
• Severe weather forecasts
Forecasting has a potentially high economic value to
the system, especially with large amounts of wind
Powering Europe: wind energy and the electricity grid