scotia wrote:TheMotorcycleBoy wrote:. I'm pretty sure that at times, when we've had very serious gales they used to shut them down. I'm not sure whether they still do, but when they do, I assume it's done out for safety considerations.
Yes - above a certain wind speed the wind turbines cease generating. Some years ago I was shown a graph of actual wind power generation versus time (in Scotland) on a very windy day. As the wind increased, so did the wind power generation, then suddenly the wind power generation plunged to near zero as the wind speed reached a critical level. In such a circumstance there is a need to plan ahead (on the basis of forecasts) to quickly bring on alternative power generators. This has become increasingly difficult with the closure of so many fossil fuelled power stations. In Scotland, I think that Peterhead is the last such power station. As mentioned in earlier posts, Nuclear Power Stations run continuously at a fixed level, so cannot help, however conventional and pumped storage hydro can help, although only slightly if there is a country-wide shut down of wind generation (for wind speeds above 50mph).
This loss of traditional fossil fuelled power stations has also created a problem if a black start is required. A black start assumes a catastrophic failure of the entire power system, and the need to start it up from zero power generation. The UK system would be split into areas, and there have been some estimates that suggest it could take up to 5 days to see the Scottish Area return to normal.
More modern turbines are getting better at controlling output without needing to shut down completely during very high wind events. And getting better at restarting without intervention following them. That is one of the things that is yielding the higher capacity factors we are seeing from modern wind farms.
Also the centre of stormy high wind events tends to be more localised than the geographic spread of low wind events. So only the most exposed turbines get shut down in high winds, not every turbine in the UK (or wherever). In contrast a low wind event can cover a very large amount of the UK, and of course the mid-winter high is the most problematic from a macro/grid perspective as that is when demand is highest, and solar PV negligible.
Bear in mind that storm/high wind events can also cause loss of conventional sources. Either through loss of grid connectivity (power lines down); or power station outages; or fuel supply outages. Nothing is perfect.
regards, dspp