[pjc50]

> 9 separate synchronous plants that had sold aFRR(?) to the TSO then failed to deliver, so when the TSO algorithms tried to adjust the oscillations, nothing happened.

Oof. This sounds like a classic of "it's only needed in emergencies, so it's only in emergencies that we find out it doesn't work".

[jakewins]

I don't know about the Spanish market, but at least in the markets I'm involved in aFRR is an "always on" product, the TSO controls your plant with a setpoint that updates in near-real-time throughout the period you've sold to them.. it's not clear to me that the product that wasn't delivered was actually aFRR though, maybe it was something else less frequently called upon.