It is my understanding that modern home EV chargers have the capability to do this to some extent, but I'm not sure if it's actually utilised?
Then when the frequency drops these consumers will automatically turn off their equipment to reduce power draw.
The seeing such a huge drop like this is extremely unusual, no doubt many systems immediately started load shedding (both voluntary and involuntary) to compensate
Below 49Hz larger consumers would be cut off in steps of ~10% of the network load. AFAIK this includes large industrial consumers who are legally required to have the equipment in place to allow for that.
If the grid really needs to shed load, it doesn’t ask, switchgear will just be programmed to physically disconnected consumers at certain grid frequencies. As a consumer you should have equipment that can survive that if it’s important to you, the consumer can then normally get rebates for loss of service later.
Special locations like hospitals are normally the last to be load shed, and the surrounding grid will shed everyone else first, before disconnecting them.
Typically it's just larger customers that can reduce demand on a very large scale. In the US there are a few startups that are aggravating residential customers into larger groups, so that each of thousands of households cuts consumption by a few hundred watts, so that the aggregate drop is big enough for the utility to care about. Utilities, at least in the US, have extremely poor capabilities for innovation and for customer relations, so that is why a startup is an intermediary.
Typically, the signal for this is not the grid frequency, however! Better to plan ahead by a bit before the frequency drops, and allow people to opt out as necessary.
You always need something that can respond quickly to unexpected events to maintain grid stability. The best signal for that is grid frequency, as it’s a very direct measure of grid health.
Many of those large consumers you speak off will be contracted to respond directly to grid frequency, either shedding load or adding supply, to make sure the grid doesn’t completely collapse if a shock event happens. That buys grid maintainers the time they need to recover the grid in a more controlled way.
That then gives the grid some time to spool up reserves. After all having your hear turn off for 10mins is better than having everything turn off for an hour, which could happen if the grid needs to shed load involuntarily.
Power companies do something similar with air conditioning units in hot areas. Customers can opt-in to have a control module installed that modulates their A/C on and off at peak loads to control demand. Customers get some nominal discount on their bill for participating.
Worked better when people weren’t working from home and it didn’t matter if your house was a bit warmer than normal for an hour or two mid-day.
Controlling this on end devices introduces a lot of distributed systems problems, like stampeding herd when all of the devices switch back on. You could try jittered back off and such, but cold customers would just unplug and replug until it worked.
The reason for 50 Hz +- 0.2 Hz isn't so much about consumers; it's about being able to run the grid. In Europe there is a long-term control loop that makes it a quite accurate 50 Hz, so synchronous motor clocks work, but that has essentially nothing to do with the normal frequency control.
You very obviously have no idea what you are talking about. Turbines blowing up because they spin a few Hz faster? Mine never did. Turbine destroyed because of "resonances" when freq too low? Mine never did that either. Not the 1100MW one at my old job, nor the two 500MW ones at the job before that and also not the 12MW one at my current job.
It sounds like you know a lot about this topic, which is great, but please omit personal swipes—that will make it much easier for people to learn from your posts.
If large power supplier disconnects without warning, that impact propagates at the speed of light. Other suppliers will respond by reducing their frequencies to keep voltage up, this is caused by generators physically spinning slower and converting their physical momentum into electrical energy. As you can imagine the momentum of a generator is large, but the stored energy is small compared to the rate of consumption.
So you need systems that can respond within milliseconds to restore some stability. Batteries are actually one of the few technologies that can do that, but mostly your looking at shedding load. Disconnecting a consumer can happen in milliseconds, after all you just need to flip a switch (admittedly they’re very large switches).
Once you shed load, then you have the time you need to spin up you “dirty” power supplies. But even the fastest response suppliers take minutes (think Hydro), not milliseconds to respond. So they’re not viable for dealing with the initial shock to the grid.
I mean, if the alternative is a blackout, having heating turned off for a few minutes over a 24 period would be preferable to a nationwide blackout? It's not as if people would suddenly freeze to death anyway.
Just curious if someone who understood this better had a good explanation for why this might be a bad idea.
If you do it for 5 minutes while the gas plants spool up, few will notice and fewer will care.