MultiPlus2 increases frequency on AC-IN with ESS assistant

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bernhards asked Mar 26, '24

MultiPlus2 increases frequency on AC-IN with ESS assistant

No AC Out used
ESS assistant
1-Phase system

One of my hoymiles inverter recognizes high frequency - so, >=51Hz. I wonder, why this happens and found out, if I turn off the MP2 it does no longer happen. The quesion is, why does the MP2 increase the frequency? This happens about 2-3 times per hour for some seconds. After 2 min, the hoymiles "is back"in ususal mode.

This happens "all day" - no matter which state the battery has. The hoymiles report this high frequency just some minutes after the hoymiles have started at around 6:00 AM.

frequency acin

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Answer 1 · 2024-03-27T11:55:05Z

bernhards answered · Mar 27 at 11:55 AM

Nobody has an idea?

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Answer 2 · 2024-03-27T18:03:52Z

sharpener answered · Mar 27 at 06:03 PM

If your system is grid-connected and synchronised so the input relays are closed then it is not physically possible for the Multi to change the system frequency so something else is going on.

If it is not grid-connected then you do not need the ESS assistant.

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Answer 3 · 2024-03-27T18:05:18Z

nickdb answered · Mar 27 at 06:05 PM

Also remember that LOM will be trying to frequency shift for ESS..

3

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bernhards commented · Mar 27 at 08:49 PM

Thanks for your answer. In https://www.victronenergy.com/live/ve.bus:grid-codes-and-loss-of-mains-detection it says "To detect a loss of mains, the inverter/charger will constantly try to shift the AC frequency."

Does someone know the details how the MP2 tries to shift the AC frequency? To which Hz does it try to do this and which timing?

Would this have an effect on all phases or only on the phase the MP2 is connected to?

As I said, the one hoymiles inverter detects "high frequency" 2-3 times each hour. I'm not able to see this issue in any other device. Even on SDM72 meter it doesn't show the high frequency - and I have configured that a message is send to me if the frequency is higher than 50,4Hz (the hoymiles reports something like 50,8Hz).

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sharpener bernhards commented · Mar 28 at 10:42 AM

I imagine the MP actually tries to shift the phase of the AC waveform but do not know for sure. If you are convinced it is a real frequency shift you can add the frequency widget to the Advanced VRM display and post it here.

For comparison this is what I get in the SW UK. The maximum deviation appears to be +/- 0.4 Hz, I suspect this is measurement error more than anything, I think the UK grid is supposed to be more stable than that:

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1711622507222.png (12.8 KiB)

bernhards sharpener commented · Mar 28 at 11:42 AM

its always 50.1Hz

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1711626131217.png (16.3 KiB)

Answer 4 · 2024-03-28T12:36:14Z

sharpener answered · Mar 28 at 12:36 PM

So if your Hoymiles is dropping out when the frequency trace looks like that then it does not seem that frequency shift is the true reason.

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