Are there times when we produce too much wind?
On very windy days there can be more wind power available than the system can accept. This is because it would displace conventional power plants below the minimum level needed for certain grid stability services. On a windy night when power demand is low the electricity System Operator may have to limit the priority access to the grid that wind enjoys. When this happens, the wind generator is dispatched down or “curtailed off” i.e. blocked from supplying electricity to the grid.
Wind generators are currently financially compensated for such curtailment, but this compensation will end from 2017. This “curtailment” is different from “constraining off” where generators are switched off to avoid overloading the local grid. Unlike curtailment, generators will continue to be financially compensated for being constrained off due to local issues. Generators pay for “firm access” – to use the transmission grid to sell electricity – and if they are constrained off due to a local grid problem, the generator is paid compensation for not being allowed to generate as much electricity as they could.