Grid frequency detecting to drop loads

I was wondering if there’s a way to sense the grid frequency either via a service or a dedicated sensor?

The idea here is, not to react under- or over-frequency events to help the grid stabilise.

So for example start the heatpump, EV charging, etc if the frequency is too high or stop the fridge/freezer /dryer/EV-charger/heatpump etc if the frequency drops.

Outages are very rare here, but emergency power supplies are quite expensive to operate and probably also not that environmental friendly, as they are all gas based.

So helping the grid with short sacrifices, like 5 minute pauses of charging sessions or having no light in the fridge would go a long way if enough people would do this.

My UPS reports frequency, although only with decihertz resolution, so it fluctuates between 60.0 and 59.9, my multimeter was 59.94 when I tested it, our grid is VERY stable where I am. Line voltage here is a better indicator of local grid load, it is 123.1V now, it is about 1 to 1.5V lower when everybody is running their aircon units.

I am not sure if there is a list of units which report frequency, mine is an “online” AC-DC-AC unit with generator support, so frequency is very important to its operation.

Hey @richieframe,

line voltage has nothing to do with grid load. The transformers will just switch between different settings to compensate on different loads.

So you get something like a saw-tooth pattern. Additionally the voltage is regulated in very small sections of the grid.

The frequency shows if the grid’s production and demand are equal. On power facilities you find them frequency displayed like a clock.

And yes I need at least two decimal places for this to work.

Here’s a web page which shows the variation and the amount of primal control power applied to the grid:

https://www.mainsfrequency.com/

Last year a new power link between Norway and Germany was taken into commission (NordLink).

During testing, something went horribly wrong, and for slightly less than a minute 1 400 MW of power was accidentally injected into the Scandinavian power grid from the European.
This caused a runaway in the frequency which increased by an entire 0,5 Hz.
Official statement from TSO StattNett.

That’s an extreme event, but gives an indication about the scale we’re talking about. 1 400 MegaWatts into a grid that’s significantly smaller than the European one (though also a very very strong one).

What I’m trying to say is it’s highly unlikely that you will be able to react to or affect the kind of events that you can measure through frequency variations by turning off a few devices in your own house. And even if you get your entire block or town to get on board with this, I would think the TSOs would rather appreciate predictability.

It’s an amicable endeavor, though, which I applaud. And a fascinating idea. May I suggest you instead try to look at predicted or historical capacity availability from your power company and schedule your large appliances based on this?

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Agreed that a single street etc won’t have an effect. But if you think about EV charging which uses several kW in a single household it definitely helps if there are many HA users doing this.

Predictability doesn’t really matter here, we just need to make sure that we have a probably of shutdown of appliances instead of shutting down everything at the same frequency threshold, like some old solar systems do.

This is also not only interesting for stabilising the grid, but also to restrict the consumption of energy from an inverter/battery storage system in case the grid fails.

I thought about this a while and I think it would be nice to have some additional attributes to each device:

  • Convince factor battery: how likely is it to be shut down to conserve energy?
  • Convince factor solar: how likely is it to be shut down to conserve power?
  • Convince factor grid: how likely is it to be shut down to stabilise the grid?
  • battery powered: should it be powered at all if the grid fails and you’re on battery power?
  • battery cutoff percentage: the percentage of battery level when the device is shut down to conserve energy
  • maximum shutoff time (on grid): how long is HA allowed to shut off a device?
  • limit CO2 emissions: fixed limit with CO2-signal
  • limit to solar power: yes/no
  • service call to shut off: like pausing a system/flipping a switch etc
  • service call to turn on: see above

This way HA could determine which devices can be shut off/on automatically without having to users to create complicated automations.

It could also be used to be called to start something automatically if the requirements are met. So you could fill the dryer in the morning and drive to work and let HA handle when there’s low CO2 production on the grid to let it run.

And you could also plug your electric car in and let it only charge on solar energy.