Phil Gavin avatar image
Phil Gavin asked

Elegant AC- coupling high frequency lockout reset?

Firstly, I am aware of the 53hz lockout condition and how to reset it and the battery voltage conditions to reset automatically.

In the large 3ph off-grid system I'm considering I intend to have both DC and AC coupling.

On a light usage day, which will be the norm, the frequency will lock out the PV inverters and I am fine with that.

Scenario 1:

However, sometimes I want to run an 11kW 3ph irrigation pump when there is good sunshine and supposedly plenty power. Now, that pump has quite a start-up current, so I want all available inversion power at the ready to be able to handle that current surge.

The thing is those PV inverters will be locked out for the day already by then, the batteries will be charged.

I don't want to restart the system via PC and I don't have a 50Hz supply, being off-grid.

Scenario 2:

The PV strings will be very early and very late power production in the day, given the big battery size they will probably still be locked out in the morning. I'd rather be using this available PV power than forcing the battery to discharge in the morning.

Is there a possibility of a binary input to force this reset on demand?

Something that I can put on a nightly timer, or operate on demand when starting the pump.

Yes, I can force the other reset methods, but they seem very unwieldy, I am looking for a more elegant solution.

MPPT ControllersAC PV Couplingfrequency
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1 Answer
marekp avatar image
marekp answered ·


Why not installing a "slow start" for the pump?

This way the pump will initially by supplied by Victron inverters from the battery, and later on PV inverters would chip with their sun power.

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Phil Gavin avatar image Phil Gavin commented ·

Thanks for the response:

I have a star/delta starter already, I'd prefer not to have to buy hardware to overcome a software inconvenience.

A 100W mini-inverter on a multi input is a cheaper option that would apparently reset the frequency if I am going to go that route.

It just boils down to still being a messy workaround.

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Phil Gavin avatar image Phil Gavin Phil Gavin commented ·


I have done some further research into soft starters and I have to thank you. Things have come a long way since star/delta starters. I had no idea solid-state SSR's had become so affordable at the current capacities they can handle.

What's more, some are available with a soft stop option. Which is also is probably good for the inverter stability and to reduce the water hammer effect.

I just hope a thyristor-based/triac starter doesn't throw the inverters a wobbler.

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