Comment by mschuster91

It doesn't work that way. Maybe in the US where everyone seems to do their own shit, particularly in Texas, but here in Europe our grid literally spans the entire continent, from Portugal through into Ukraine's front lines, and from Norway even down towards Africa. It's a three phase grid that is in synchronized phase everywhere. Like, literally everywhere.

Grid frequency cannot be used at scale to coordinate energy production as a result, because the grid elements themselves don't know why the frequency is going down on its own or where the cause is. For that you need to monitor the country or region crossing to see where energy is flowing and aggregate this.

Drop a couple gigawatts from the production side, for example, all at once and the frequency will immediately drop, only not crashing due to the mechanical inertia of the large power plants. Immediately, electricity and physics will lead to current balances redistributing and automated systems will kick in (e.g. gas peaker plants ramp up in a matter of seconds, battery storage kicks in even faster). But when too much capacity gets dropped, the available spare capacity isn't enough and eventually the first lines will trip due to overcurrent or frequency deviation. That is what happened in Spain, made worse by the fact that inverters don't have mechanical inertia and so immediately more inverters dropped out for safety reasons as the frequency sagged too much for their protection circuits. The inverse, adding a couple of gigawatts of consumers, causes the same effect.

That's also why very large consumers such as smelters must contact the local electricity distributor in advance before any load change - dispatch must know precisely when the consumer will drop or add load, so that other plants can be regulated up or down to avoid too much of a sag or hike in frequency.