question

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jean-paul-1 asked

Grid Support and Inverter Freq.Shifting

Hi,

I have two problems on a 3-phase Victron Multiplus 5000/48/70-100 with battery pack (lead acid 24 x 2V / 1150 Ah each) operated as an island. Three SMA inverters and two Victron MPPT 150/60.

One is the gird supply: when the batteries are low (now visible due to less power production and more demand with a heat pump for heating the house)

The other is the freq.shifting for the inverters (SMA)

The grid supply assist doesn't work at all. The assistants are programmed (general flag and generator start-stop) but for some strange reason the grid doesn't start when batteries are low. I've upgraded the multiplus (all of them) to the latest firmware 487 and reprogrammed the system from blank. The same problem ...

The freq.shifting is even stranger, when the PV inverter Support assistant is programmed, the Multiplus continuously switches the inverters off and on (50 to 53 Hz). It starts working AFTER a heavy load (higher then the combined inverted power) ... after that it works normal

Both problems are a pain because or the batteries can be overcharged or the batteries can be completely discharged. Now I have to manually interfere all the time.

I've uploaded three VSC files (added the extension PDF otherwise I could not upload the files) for the multi's maybe someone can take a look and see if I'm doing something wrong.

SMA 1 = 3kw inverter = 3500 wP panels

SMA 2 = 3kw inverter = 3250 wP panels

SMA 3 = 3kw inverter = 3370 wP panels

Any help is appreciated !!!

Thks,

Jean-Paul

Multi 1.vsc.pdf

Multi 2.vsc.pdf

Multi 3.vsc.pdf

gridfrequency
multi-1vsc.pdf (5.9 KiB)
multi-2vsc.pdf (5.9 KiB)
multi-3vsc.pdf (5.9 KiB)
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1 Answer
jean-paul-1 avatar image
jean-paul-1 answered ·

I finally have found out what the problem was.

First, a 3-phase internal system does not work with a 1-phase grid supply used as a generator. The inverters don't pick up the 120° phase shift and therefor don't "open" the possibility to charge.

The freq.shift issues were generated because I changed the assistants without loading the latest firmware .... After upgrading to the latest firmware everything works fine again. Who could have thought about that one .....

So, after all this ... back to 1-phase parallel system

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Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.