I have always argued, the biggest instability to the grid, is large thermal power plants, especially nuclear. Because, when a large plant goes off-line, we are talking up to 2GWatts (2,000,000,000W). You have to suddenly find alternative power rapidly. Even, with pumped Hydro, there is a delay, to ramping up power, to meet the short fall. This time delay, will be enough, to cause a domino effects, where safety devices, open, to protect other equipment.
When I worked at Bolton’s Thermal Recovery plant, if we had an outage. The Grid operator hardly notice, the 6 MWatts (if we lucky enough to produce that much), they suddenly lost, to out outage! It is entirely a different matter when you lose, GigaWatts of power. As this article points out, Spain had two nuclear units (2GWatts) off-line! Was this planned or an emergency shut-down? As it was, I believe, this caused the cascade affect, plunging the Iberian Peninsular into a massive electricity black-out. With even mobile phones and WiFi being unavailable.
It is long overdue, to stop throwing money at nuclear power, which is not a renewable, not emissions free but a very toxic legacy, for future generations.
patricktsudlow 