Quattro allowing power backwards unregulated through to batteries

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sunshinepower asked Aug 23, '22

Quattro allowing power backwards unregulated through to batteries

Hello, I am hoping that someone could help me with an issue with my off grid setup.

The system uses x2 Quattros 10kva set up as 2 phase 180 degrees apart.

I use solar charge controllers to charge lithium batteries, 48volt system.

There is nothing else connected to system as in no ac input.

I do not use the chargers on the inverters, they are switched off.

Outputs are on ac1

Everything works fine under normal use. Solar chargers do their job, everything works ok.

A problem exists when I switch on a separate solar system on one of the lines.

The other system is 5kva with an inverter, use to be for grid tie.

Things look ok to start with initially, The load on corresponding inverter drops off as the load is being supplied by the other system all looks good.Then the voltage starts to go up far in excess of the battery peak voltage settings which is 57.7. The voltage climes to over 60v and the overvoltage alarms going off.

To double check, I switch off the solar arrays to make sure there is no problem there and the problem persists. I then turn off the separate solar system and voltage starts to come back to what it should be. So there is definitly power coming back through the inverter unregulated into my batteries some how.

The charge function on inverters are turned off.

Its a 240volt system and when the other solar array comes on line the voltage on that line is around 251volts.

As far as I can see somehow the higher line voltage is causing a feedback into batteries in an unregulated way.

Can anyone please give me an idea as to why this is occurring and how it could be fixed, am I missing something or can I just not use the other system. Or can I even increase the Quattros inverter output to match or surpass the other inverter voltage.

Thanks

quattro 10kva

2 |3000

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Answer 1 · 2022-08-23T09:44:23Z

wkirby answered · Aug 23, 2022 at 09:44 AM

You did not mention anything about "PV Inverter Support" assistant. Do you have this assistant configured in the Quattros and what are the settings.
When you have a PV inverter on the AC output the Quattros need to know about that and also the capacity of the PV array and the Inverter power. Then the Quattros will be able to frequency shift to cause the PV innverter to throttle back or to switch off when the Voltage limits are reached.
Without the PV Inverter Support assistant loaded, the PV Inverter will simply act as it is designed to do and push power on the AC line, that power has to go somewhere so it ends up in your batteries via the inverter.

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

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sunshinepower commented · Aug 23, 2022 at 12:54 PM

Thanks wkirby, I don't have the PV Inverter Support assistant configured into the Quattros, thanks for pointing that out.

It may not be as easy as just loading the PV Inverter Support assistant though.

I have looked over some of the info. I am not completely sure and I am hoping you can clarify this but it seems that there may need to be a data connection between the Quattros and the PV Inverter to do the frequency shifting. Can the Quattros with the PV Inverter Support assistant work with the PV inverter and do the frequency shifting without any data connection.

The Quattros and PV inverter in my set up are quite far apart and any data connection may be quite difficult.

If the Quattros could frequency shift by just the 240 volt line connection from the PV inverter it would make things alot easier but maybe they would tend to follow each other to stay in phase and thats why a data link is needed to keep the phase difference when needed, is this correct. And also my PV inverter may not have the capacity to work with the Quattros to do the phase shifting, is there a way of knowing their compatibility.

Does the Quattros do the frequency shift or do the Quattros tell the PV inverter to shift frequency.

Any knowledge about this would be very helpful to determine how to proceed.

Thanks

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Answer 2 · 2022-08-23T15:26:54Z

johanndo answered · Aug 23, 2022 at 03:26 PM

The Quattro shifts the frequency AFAIK. No need for data connection, that is why frequency shift is used to communicate in the first place.

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sunshinepower commented · Aug 24, 2022 at 07:52 AM

Yes, I thought that the phase shift was the process of causing a change in power, which was not correct. After some more research I now understand that that the phase shift is a method of communication from the Quattro to the PV inverter to ramp the PV inverter up or down.

Thanks for help

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