I don't think we're able to tell from the data if one is the cause of the other, are we? Since if production was lost, load would have to be shedded to balance the grid, and if load was lost (e.g. due to a transmission failure), production would have to be disconnected to balance the grid.
That started from a combination of a lightning strike and generator trip, but turned into a local cascade failure as lots of distributed generation noticed that the frequency was under 49Hz and disconnected itself. I suspect the Spanish situation will be similar - inability to properly contain a frequency excursion, resulting in widespread generator trips.
(I suspect this is going to restart a whole bunch of acrimony about existing pain points like grid maintenance, renewables, domestic solar, and so on, probably with the usual suspects popping up to blame renewables)
Renewables were a factor in the blackout here in Brazil a couple of years ago: the models used by the system operator did not correspond to reality, many solar and wind power plants disconnected on grid disturbances quicker than specified. That mismatch led the system operator to allow a grid configuration where a single fault could lead to a cascade (more power was allowed through a power line than could be redistributed safely if that power line shut off for any reason), and that single fault happened when a protection mechanism misbehaved and disconnected that power line. The main fix was to model these solar and wind power plants more conservatively (pending a more detailed review of their real-life behavior and the corresponding update of the models), which allowed them to correctly limit the power going through these power lines.
If you want an excruciating level of detail, the final 614-page report is at https://www.ons.org.br/AcervoDigitalDocumentosEPublicacoes/R... (in Portuguese; the main page for that incident is at https://www.ons.org.br/Paginas/Noticias/Ocorr%c3%aancia-no-S...).
If you have a large spinning inertial mass like a factory motor or a power generation turbine, it's extremely important. Imagine a manual car transmission, but there's no slip-clutch, you need to perfectly align engine with the wheels rotating at 300mph, and the inertial mass you're up against if it's not perfectly synchronized is a freight train.
That's why generators trip offline in a blackout cascade if the frequency deviates out of spec. The alternative is your turbine turns into a pile of very expensive shiny scrap metal.
Frequency coordination is absolutely critical, via phase coordination. A large generator must not get significantly out of phase. So frequency going out of spec triggers the generator to "trip" (disconnect).
I don't know what specific threat is addressed by tripping generators offline when the frequency deviates by 1 Hz. Are they so mechanically fragile that is already damaging to them, or is it a precautionary measure because that kind of instability is likely to precede sudden frequency or phase jumps that are damaging?
Both actually. A frequency mismatch between what the grid has and what the turbine is supplying causes significant thermal losses, so you got to trip the generator anyway rather sooner than later, but a significant frequency deviation is always a warning sign that something is Massively Broken and requires immediate attention to find the cause - too low a frequency means you need to shed load immediately, too high means you need to shed generator capacity immediately.
Some plants the system operator has the ability to send a signal to instantly open the generator breakers to shed generation if necessary.
> One of the parent posts correctly identified there are thermal issues with operating at significantly off nominal frequencies for extended time periods
Yeah, that's very much the problem. Power sources that burn fuel to generate electricity generally don't like being run at 100% throttle for long periods of time. In a low frequency situation you've got potentially multiple countries of generators all running flat out trying to get the frequency back to where it's supposed to be. If they reduce throttle without having something else come online to take the place of the energy they were producing, the line frequency drops further.
Nuclear has its own issue with running full throttle: once a plant has been running at 100%, it takes time for it to throttle back down and might not be possible to immediately throttle back up. There's decay heat from the fission products and there's short-ish lived (up to 40-50 hours though) neutron poisons.
I have only worked on one steam turbine and it had no issue running with the throttle valve wide open all day long.
Every system has a maximum continuous output capacity and I would expect the controls to limit the output so as not to damage the equipment.
I’m curious what sources you are aware of that can’t run at a maximum continuous output all day
Its like a three legged race. You and your partner have to run in synchronism. If either of you slows down or speeds up, the other can trip and fall over taking both of you out.
Might even give you clues about something big tripping offline.
Probably lots of false alarms, but if it an outage is particularly bad for you, good to know as soon as the system operators do.
Obviously over the internet could work too, but who wouldn’t love their own box?
When the phase gets pulled down hard like what nearly happened in Texas and what probably happened here, it'll go from looking like the background noise of phase changes to catastrophic in just a few seconds. It isn't like you'll get warning an hour ahead of time. You'll probably notice your computer monitor going dark before your grafana graph refreshes.
Yes, it's not that hard. There's smart meters and plugs that have frequency measurement built in.
You can even do it with an audio cable: https://halcy.de/blog/2025/02/09/measuring-power-network-fre...
Having the grid operate at 49.99Hz instead of a perfect 50.00Hz for a day will make your clock lose 17 seconds, but it's completely harmless. That's normal regulation, not a gradual failure. The grid chooses to compensate for that by running at 50.01Hz for a day, but that's solely for the benefit of those people with old-school clocks - the grid itself couldn't care less.
A failure means the frequency drops from 50.23Hz to 48.03Hz, probably within a single second. You'd notice as your clock stops ticking due to the resulting power outage.
if a high power transformer goes out of tune... it melts or blows up (or both); it'll try to shut itself down before that. getting it back on becomes a problem if other transformers do the same thing, which is apparently what happened in the whole country.
In reality, power generation equipment will disconnect itself if the frequency is too low/high to avoid catastrophic failure.
[1] https://transparency.entsoe.eu/load-domain/r2/totalLoadR2/sh...
[1] https://transparency.entsoe.eu/transmission-domain/physicalF... [2] I'm not necessarily blaming the engineers, but the politicians who force those engineers to put square pegs in round holes. For example, I can imagine politicians making a short term decision to skimp on energy storage while increasing renewable penetration. Surely renewable systems must be less reliable without storage given the lack of rotational inertia?
[1]: https://www.spiegel.de/wissenschaft/stromversorgung-in-spani...
If the addition of renewables leads to an unstable grid, it is irrelevant if the grid is then restarted with the help of renewables.