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alejandrocortes avatar image
alejandrocortes asked

Frequency shift stacked at 51.5 Hz during the night

Hello. I have a three phase Qattro off-grid set-up with Pylontech batteries and SMA inverter AC coupled. Frequency shifting is lowering the solar production when battery is full but during night frequency is not recovering 50 Hz during battery discharge. It keeps 51.5 Hz value. This avoid the solar inverter to start generating when sun arises. Frequency is only recovered when generator starts because of low battery. The set-up uses the PV assitant for frequency shifting and I have check the settings many times. Can anybody help me? I've seen similar cases to mine but with no solution.

Thank you.

frequency
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3 Answers
Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

What is your battery voltage and the charge setting in the MultiPlus?
The voltage has to drop 0,8V below the float voltage to reset the frequency.

https://www.victronenergy.com/live/assistants:pv-inverter-support#q1_-_the_system_is_locked_to_53_hz_and_does_not_resume

Maybe it helps if you raise the float voltage in the settings of the MulitPlus.
The system will still use the CVL send by the battery via DVCC.

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alejandrocortes avatar image alejandrocortes commented ·

Hello Matthias.

Thank you very much for your answer. The charger settings I have are those recomended for Lithium Pylontech batteries, this is 52 V as absottion voltage and 51 V as float voltage. The measured battery voltage drops below 50,2 V but the frequency does not reset. For example just in this moment the battery voltage is 49,46V and the output frequency is 51,4 Hz. I know the link that you posted and it seems to be related. Do you still think thatraising float voltage setting could help?

Thanks.

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alejandrocortes avatar image
alejandrocortes answered ·

Hi Matthias.

I increased float voltage from 51.00 V to 51.90 V but I don't see any difference. At this moment there is no solar production and the frequency is stacked at 51.5 Hz. I attach a capture of the status. Any other idea?

Thank you very much.

capture.jpg


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Paul B avatar image
Paul B answered ·

try moving your pv assistant in the Quattro to be the last one in the list of assistants, in the Master unit, just for safety I also would add it to all the slaves as well.

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