It's hot in parts of Eastern Europe at the moment - this happens in summertime I believe - and so people are switching on the airconditioning in droves.
In Poland this has produced some pretty major problems because the electricity grid can't supply sufficient electricity to meet demand. It's a familiar story: Poland relies on coal for the bulk of its electricity, but nobody wants to invest in new coal-fired power plants because the market is being rigged in favour of renewables and the EU is going to shut them all down anyway. Meanwhile there is hardly a puff of wind to be found anywhere in Europe so Poland's wind fleet is not helping either.
;)
The solution is the same one planned for the UK - industrial users are switched off so that workers, like the wind turbines, sit idle.