question

bernhards avatar image
bernhards asked

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.


frequencyacin
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6 Answers
bernhards avatar image
bernhards answered ·

Nobody has an idea?

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sharpener avatar image
sharpener answered ·

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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nickdb avatar image
nickdb answered ·

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

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bernhards avatar image bernhards commented ·

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 avatar image sharpener bernhards commented ·

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:

1711622507222.png


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1711622507222.png (12.8 KiB)
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sharpener avatar image
sharpener answered ·

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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bernhards avatar image
bernhards answered ·

Looks like the issue is a issue on the Hoymiles itself. Firmware issue.

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sharpener answered ·

Glad you solved it!

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