Re: In other news... first new UK nuclear power station approved
"Actually wind power is as predictable as tides, you know what weather is coming days ahead and take appropriate action"
Not according to National Grid, based on experience to date:
"In our previous consultation, it was explained that we had experienced changes in
wind output of 50% over 2 hours against our current relatively low levels of wind
penetration. Similar changes in output have been seen in continental Europe where
there is a higher level of penetration with greater dispersion. It is necessary to ensure
in the event of a loss of wind output, sufficient reserve is available in appropriate
timescales to cover such an eventuality. .....
..... the forecast aligns with actual generation for a majority of the
week. However, within each week there is one day where the error is significant.
It is apparent from Figure 2, that in this instance the forecast profile for 26-February
was consistent with the actual output, but the magnitude or level of output was over
forecast by between approximately 30% and 80% over the 26th February 2010....
...An additional operational challenge that will increasingly present itself in the future is
that which can be termed wind cut-out. This occurs when wind speeds are sufficiently
high that wind turbines automatically shut down to maintain structural integrity.
6.19 The speed at which this happens will vary depending on the location and size of wind
turbine, although on-shore turbines tend to cut out at wind speeds of ~25m/s.
6.20 National Grid has recently witnessed such an event, when wind speeds in Scotland
were sufficiently high to create this phenomenon. National Grid does not currently
have the wind speed data for all wind farm locations; however, Figure 5 illustrates the
effect witnessed on 3-February 2011.
6.21 The effect of cut out can have a significant impact, not only due to the resultant loss
in expected generation but also the speed and additional uncertainty that can arise
when production starts again as wind speed drops. In the example shown above, a
significant decrease in generation occurred when wind speed exceeded 25m/s, which
resulted in a reduction of ~50% of the wind production over the course of an hour. As
wind speed dropped below 20m/s, output was restored before a further loss a short
not THAT predictable, then.......