> The cause is the frequency drop that was not compensated by the inertia of rotating turbines due to increasing use of photovoltaics.
But what caused the frequency drop? Large-scale grids are designed and operated in such a manner that any single fault, even one which causes a frequency drop (like a generator or a power line getting disconnected), will not cause a blackout. Which means: if there isn't enough inertia to compensate the frequency drop caused by a single fault anywhere in the grid, the system operator will either order photovoltaics and wind turbines to reduce their generation to a safer level, or order traditional rotating generators to operate as synchronous condensers (which adds inertia without adding generation).
Which means that either there was a double fault (two faults close enough in time that there wasn't enough time to reconfigure the system to a safer state before the second fault), or that the modeling of how the photovoltaics and wind turbines would react to a single fault was incorrect (for instance, expecting them to stay connected for longer on that level of frequency drop). My personal guess is that we're going to see a repeat of what happened here in Brazil in 2023, as I explained in another comment on an earlier thread (https://news.ycombinator.com/item?id=43821801), where a single fault was enough to destabilize the system because the inverters in wind and solar power plants disconnected earlier than expected.
According to my friend, the freq drop was caused by a sudden large supply surplus over the instantaneous demand. Nuclear plants were offline and there was nothing to absorb the freq drop at that moment.
In the case of the rotating generators, yes. In the case of the solar panels, I do not know: I guess it depends on the inverters characterists? Spanish is not my native language, so I may have mixed it up when talking to him.
But what caused the frequency drop? Large-scale grids are designed and operated in such a manner that any single fault, even one which causes a frequency drop (like a generator or a power line getting disconnected), will not cause a blackout. Which means: if there isn't enough inertia to compensate the frequency drop caused by a single fault anywhere in the grid, the system operator will either order photovoltaics and wind turbines to reduce their generation to a safer level, or order traditional rotating generators to operate as synchronous condensers (which adds inertia without adding generation).
Which means that either there was a double fault (two faults close enough in time that there wasn't enough time to reconfigure the system to a safer state before the second fault), or that the modeling of how the photovoltaics and wind turbines would react to a single fault was incorrect (for instance, expecting them to stay connected for longer on that level of frequency drop). My personal guess is that we're going to see a repeat of what happened here in Brazil in 2023, as I explained in another comment on an earlier thread (https://news.ycombinator.com/item?id=43821801), where a single fault was enough to destabilize the system because the inverters in wind and solar power plants disconnected earlier than expected.