Comment by vvillena

The Spain blackout was caused by a multitude of reasons. Lack of stability was one of the factors, but there were other causes, such as energy generation facilities disconnecting while the oscillations were still under a nominal range, or a generator ordered to become online to induce stability, that started driving the load in the wrong direction. All this was compounded by a distribution network unable to redistribute or at least isolate the problems to individual regions, resulting in a complete blackout.

All in all, it's several things that need to be reinforced. The distribution network needs to be smarter. The energy generation facilities need to be tested through their entire voltage range, so they can be counted upon. And there has to be more voltage inertia available in the network.