Viktor Stepanenko avatar image
Viktor Stepanenko asked

AC-coupled PV with Fronius PV Inverters

Hello! Is it possible to increase the speed of limiting the output power of the solar inverter Fronius in the ac-coupled system? The frequency shift settings in the ESS assistant set by default (start - 51 Hz, minimum - 52.7 Hz, disconnect - 53 Hz), but if the mains is lost and the battery state of charge is 100%, we need turn off the Fronius without delay. Is it possible to do this for example by increasing the sensitivity of the Fronius (to make the range between the normal frequency and the frequency of the shutdown as small as possible, for example disconnect frequency to 51Hz), or we have some other way to solve this problem? Thanks for your answers!

AC PV CouplingFroniusfrequency
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rainerb avatar image rainerb commented ·

Did you experience/test that this is a real issue?

I have an AC-coupled Fronius galvo and it is very sensitive to grid changes. In case of a grid failure (or in the moment when the multiplus transfer relay switches) the Fronius switches off with any error code (overvoltage, undervoltage, overcurrent or whatever).

After that it ramps up again within the microgrid and the frequency shift does its job.



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Viktor Stepanenko avatar image Viktor Stepanenko rainerb commented ·

Hello, Rainer

Yes, I do. My system is shut down when the Fronius work on full power (and battery SOC is 100%) and then suddenly mains lost. I think that it can be through my voltage stabilizer, that set on the output of my three-phase system. Maybe voltage stabilizer shuts down when the Quattro shifts frequency up to 53Hz. That is about why I want to reduce the range of frequency shift to 51Hz.

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Kristof G. avatar image Kristof G. Viktor Stepanenko commented ·


i have also an ABB on the output of my quattro and he also shutsdown when my battery is full ,a min. later he starts up and goes full power, and the proces starts again by turning off and on again...

its the freq. shift... but i didnt manage to control it..because i dont have the program to login to the inverter... now iam testing with the ABB inverter on the ac input side...

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2 Answers
Paul B avatar image
Paul B answered ·

you set those trigger levels in the ESS assistant to as close as you want.

however how the fronius response, this would be in there settings and Victron has no control over that. you would need to contact them to change those settings or have a program to do those adjustments

1559387839861.png (28.9 KiB)
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abrahamsolar avatar image
abrahamsolar answered ·

Hello, @Viktor Stepanenko & others. If the battery capacity is small relative to the PV wattage, I think that would make "overshooting" more likely to occur. Especially with fancy/costly batteries which are capable of fast recharge's tempting to use a fairly small amp hour rating compared to the PV. Some battery manus impose minimum sizing constraints to avoid this problem, so it's something to consider. Good solutions wished for you from CO, USA>

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