They don't really disconnect it like that in these circumstances (as in they choose what to disconnect). As far as I know generation plants will start disconnect when grid frequency is <49Hz or >51Hz (at least in the UK) automatically as it's all starting to go very wrong. This is what causes this huge cascade effect. Roughly speak less frequency means there is more demand than supply and the other way round for higher frequencies.
This has changed a lot though, as even home batteries afaik will start discharging if they start noticing the frequency dropping to provide some support on generation. But if it's dropping too fast and too quickly it won't help.
But yes they do have very granular info on all the HV sources and how much load is on them.
This has changed a lot though, as even home batteries afaik will start discharging if they start noticing the frequency dropping to provide some support on generation. But if it's dropping too fast and too quickly it won't help.
But yes they do have very granular info on all the HV sources and how much load is on them.