6 ms·

As someone who doesn't speak German and has only a cursory understanding of the electrical grid - how significant is this?

mherrmann 6y ago
One of the comments in the Twitter thread was "I've been measuring the grid for 10 years and have never seen anything like this".
OnACoffeeBreak 6y ago
In general, slowing frequency is an indicator of a heavily loaded grid. I don't have an appreciation how much the frequency can practically be off the nominal 50 Hz (in Europe) before it indicates grid failure.
- cookieswumchorr 6y ago
  does this happen if the heavy load is at region scale? because at small scale (within a village in my experience) the voltage would drop. I didn't measure the frequency though.
- foobarian 6y ago
  This is fascinating to me. What is the mechanism by which this happens? The added load causes an average slow down across the population of actual spinning generator bits?
  - gefh 6y ago
    Yes, the generators literally have to push harder and slow down.
    - deleted 6y ago
      [deleted]
  - thatcherc 6y ago
    That's exactly right. Extra electrical draw on the grid (or a loss of electrical production elsewhere) causes the turbines in power plants to physically spin slower due to increase load on each turbine. An (imperfect) analogy would be if you and a friend were biking up a hill on a tandem bike. If a third person hopped on the handle bars (or your friend stopped pedaling) the bike's wheels would slow down, assuming you are putting a constant amount of power into the pedals.
    - jonsen 6y ago
      Tangentially (or maybe tandemially :) this illustrates the problem of synchronizing an e.g. solar power unit delivering to the net. The person jumping on a multicycle in speed must synchronize their feet to the rotating pedals to actually add power.
  - nabla9 6y ago
    Most power generators are rotating engines (there are exceptions like solar and and batteries that use power inverters). Increasing load decreases frequency exactly the same way as anything rotating slows down when you increase load. Electric grid is like chain in a bike. Generator producing power leads a little. Loads follow little behind. They are not exactly matched. Like bike chain is tighter to one direction and looser to other under load. Mass of rotating generators provide kinetic inertia into the grid so it reacts very little to small variations in the load. But if the load becomes too high and turbines can't speed up, frequency of the grid slows down.
- fennecfoxen 6y ago
  In practice it depends a lot on how a bunch of specific power equipment is set up. Remember that the A/C power grid needs to be synchronized across the entire continent, so each A/C generator that makes A/C power and runs at 50Hz needs to have the position of a physical object (the rotors) match the position in the current power cycle. If it's badly wrong, you have power-plant sized energy feeds fighting each other — imagine a train wreck, two massive oversized freight trains smashing right into each other. It's like that, but with electricity instead of a physical collision. This can obviously cause major damage, so once you start deviating from the reference frequency by enough, it's safer to just cut off the interconnects and go offline.
- posix_me_less 6y ago
  Under 49Hz they start disconnecting consumers. If that does not stabilize the dropping, under 47.5 Hz they disconnect the power plants and the network fails. [1] [1] https://www.netzfrequenzmessung.de/abschaltung.htm https://www.netzfrequenzmessung.de/abschaltung.htm
jaywalk 6y ago
Very. It means that the grid suddenly lost a significant amount of generating power.
- throwaway0a5e 6y ago
  Or added a ton of load faster than it could ramp up
  - fennecfoxen 6y ago
    The graphs show the frequency falling off a cliff, which is more consistent with a sudden loss.
  - jaywalk 6y ago
    It could be that, too. But I'm at a loss trying to think of how that much load could be added so suddenly.
    - throwaway0a5e 6y ago
      I didn't feel like reading a low effort anecdote about that one time someone tried to run their house off of some rooftop solar and a golf cart battery and all his ceiling fans slowed down and everything died when the fridge kicked on so I figured I'd bring load based frequency reduction into the discussion on my own terms. I can't think of any practical way to use that much power all at once either. On a small country size grid with a lot of renewables that can't ramp quickly I could see some foundries pulling it off.
    - davrosthedalek 6y ago
      Maybe somebody connected woodpecker [1] to the European grid? But I guess even that does not need enough power. [1] https://en.wikipedia.org/wiki/Duga_radar https://en.wikipedia.org/wiki/Duga_radar
      - shawabawa3 6y ago
        Wikipedia says that's 10MW The drop was around ~4.5GW
tashbarg 6y ago
The grid was overloaded significantly, but not critically. For everybody concerned with the grid, this is a major event because the grid is usually extremely stable. For everybody else, it's not significant. Grid operating as designed. This graph shows the frequency drop we encountered: https://www.netzfrequenzmessung.de/bilder/2020_01_08_Abschaltgrenzen.jpg https://www.netzfrequenzmessung.de/bilder/2020_01_08_Abschal... The red line at 49Hz is when things actually get switched off for the first time (12.5% of load).

mherrmann 6y ago

One of the comments in the Twitter thread was "I've been measuring the grid for 10 years and have never seen anything like this".

OnACoffeeBreak 6y ago

In general, slowing frequency is an indicator of a heavily loaded grid. I don't have an appreciation how much the frequency can practically be off the nominal 50 Hz (in Europe) before it indicates grid failure.

cookieswumchorr 6y ago
does this happen if the heavy load is at region scale? because at small scale (within a village in my experience) the voltage would drop. I didn't measure the frequency though.
foobarian 6y ago
This is fascinating to me. What is the mechanism by which this happens? The added load causes an average slow down across the population of actual spinning generator bits?
- gefh 6y ago
  Yes, the generators literally have to push harder and slow down.
  - deleted 6y ago
    [deleted]
- thatcherc 6y ago
  That's exactly right. Extra electrical draw on the grid (or a loss of electrical production elsewhere) causes the turbines in power plants to physically spin slower due to increase load on each turbine. An (imperfect) analogy would be if you and a friend were biking up a hill on a tandem bike. If a third person hopped on the handle bars (or your friend stopped pedaling) the bike's wheels would slow down, assuming you are putting a constant amount of power into the pedals.
  - jonsen 6y ago
    Tangentially (or maybe tandemially :) this illustrates the problem of synchronizing an e.g. solar power unit delivering to the net. The person jumping on a multicycle in speed must synchronize their feet to the rotating pedals to actually add power.
- nabla9 6y ago
  Most power generators are rotating engines (there are exceptions like solar and and batteries that use power inverters). Increasing load decreases frequency exactly the same way as anything rotating slows down when you increase load. Electric grid is like chain in a bike. Generator producing power leads a little. Loads follow little behind. They are not exactly matched. Like bike chain is tighter to one direction and looser to other under load. Mass of rotating generators provide kinetic inertia into the grid so it reacts very little to small variations in the load. But if the load becomes too high and turbines can't speed up, frequency of the grid slows down.
fennecfoxen 6y ago
In practice it depends a lot on how a bunch of specific power equipment is set up. Remember that the A/C power grid needs to be synchronized across the entire continent, so each A/C generator that makes A/C power and runs at 50Hz needs to have the position of a physical object (the rotors) match the position in the current power cycle. If it's badly wrong, you have power-plant sized energy feeds fighting each other — imagine a train wreck, two massive oversized freight trains smashing right into each other. It's like that, but with electricity instead of a physical collision. This can obviously cause major damage, so once you start deviating from the reference frequency by enough, it's safer to just cut off the interconnects and go offline.
posix_me_less 6y ago
Under 49Hz they start disconnecting consumers. If that does not stabilize the dropping, under 47.5 Hz they disconnect the power plants and the network fails. [1] [1] https://www.netzfrequenzmessung.de/abschaltung.htm https://www.netzfrequenzmessung.de/abschaltung.htm

jaywalk 6y ago

Very. It means that the grid suddenly lost a significant amount of generating power.

throwaway0a5e 6y ago
Or added a ton of load faster than it could ramp up
- fennecfoxen 6y ago
  The graphs show the frequency falling off a cliff, which is more consistent with a sudden loss.
- jaywalk 6y ago
  It could be that, too. But I'm at a loss trying to think of how that much load could be added so suddenly.
  - throwaway0a5e 6y ago
    I didn't feel like reading a low effort anecdote about that one time someone tried to run their house off of some rooftop solar and a golf cart battery and all his ceiling fans slowed down and everything died when the fridge kicked on so I figured I'd bring load based frequency reduction into the discussion on my own terms. I can't think of any practical way to use that much power all at once either. On a small country size grid with a lot of renewables that can't ramp quickly I could see some foundries pulling it off.
  - davrosthedalek 6y ago
    Maybe somebody connected woodpecker [1] to the European grid? But I guess even that does not need enough power. [1] https://en.wikipedia.org/wiki/Duga_radar https://en.wikipedia.org/wiki/Duga_radar
    - shawabawa3 6y ago
      Wikipedia says that's 10MW The drop was around ~4.5GW

tashbarg 6y ago

The grid was overloaded significantly, but not critically. For everybody concerned with the grid, this is a major event because the grid is usually extremely stable. For everybody else, it's not significant. Grid operating as designed. This graph shows the frequency drop we encountered: https://www.netzfrequenzmessung.de/bilder/2020_01_08_Abschaltgrenzen.jpg https://www.netzfrequenzmessung.de/bilder/2020_01_08_Abschal... The red line at 49Hz is when things actually get switched off for the first time (12.5% of load).