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David avatar image
David asked

Frequency Shifting and Generator

For off grid sites with a generator and AC coupled solar.

Is there a chance that when the Gen comes on (for load support etc), and if the battery if full, that the AC coupled solar (ramped down) , then , the frequency shifting is overridden by the Gen set (if genset provides 50Hz). Is there a chance energy could back-feed and damage genset?

Guess this could happen if the genset is small and the Fronius is large?

If yes to above, is there recommended ways to avoid this in the manual? I've watched the fantastic webinar in the AC coupling (Fronius & Victron webinar) but nothing was mentioned.

We have a work around, but would prefer to use one provided by the manufacturers.

https://www.victronenergy.com/live/ac_coupling:fronius

Look forward to your feedback

David

Fronius
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2 Answers
Paul B avatar image
Paul B answered ·

There are a few different ways to handle this.

As the generator is basically the grid and if the loads are low and the solar output is hi and the batteries are full then its possible that the excess power from the solar would feed back into the generator and the inverters cant increase the Freq while the gen is connected. A lot will depend on the grid tie setup, but if you are only using frequency shift to shut the grid tie down then the below will work, (presuming that the frequency shift is working in the first place)


so one easy way around this is to set up assistants and to set them up to turn AC1 IN OFF when the batterys are over say 95% . you can also set load limits etc etc

and then a sececond assistant to close it when they are under say 80%

or another way is to use the generator autostart start and stop feature, so that the gen is shutdown when the batteries are full.



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Daniël Boekel (Victron Energy Staff) avatar image
Daniël Boekel (Victron Energy Staff) answered ·

Hi @David

With most generators there won't be any problem:

-when PV is exported to the generator, it will turn faster and/or raise voltage, the exporting device (PV inverter or Victron inverter) will then stop exporting.

what you can also do is provide coupling between generator and the rest of the system to disable feed-in when it's running.

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