In another thread that comments the report it was said that most inverters used in Spain for the renewable energy sources do not implement a control policy to generate an adequate reactive power to compensate the phase fluctuations of the grid, like a synchronous electromechanical generator would do. The inverters only disconnected from the grid when the frequency went outside the permitted range.

Ensuring that the inverters produce compensating reactive power would have been easy to do, but it was not done simply because there were no regulations that requested this. Obviously, as a consequence of the report, this is likely to change.

Yeah, been trivial forever. In the US it became a requirement for new all utility scale non-synchronous generators a decade ago. And then a bunch of statewide rules for rooftop solar as well.

https://www.ferc.gov/news-events/news/ferc-moves-implement-f...