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n-dee avatar image
n-dee asked

frequency shift on AC OUT of multiplus II

I recently switched our 6x Multiplus 5000 to 3x Multiplus 10.000 - nothing else changed.
Since then I can see frequency shifting on AC-Out while AC-In is stable at 50,1Hz. (See gif)2023-07-12-14h50-02.gif

Ist there any known issue with Multiplus 10.000 ?

acout
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Alexandra avatar image Alexandra ♦ commented ·

@N-DEE

Are you offgrid or on grid?

In erting anything between 49.9 and 50.1 is acceptable.

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n-dee avatar image n-dee commented ·

Hi - I'm ongrid

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2 Answers
n-dee avatar image
n-dee answered ·

One more thing I just noticed.

When I'm offgrid, the multis switch between 49,9 and 50,1 - and a while later they switch to 53,1 and back again to 49,9, 50,1 and so on...

When on 53,1 the old light bulbs get lighter - thats really annoying.

Are the multis faulty?

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n-dee avatar image n-dee commented ·

last powerfailure I found out that the switching to 53,1 and back only occurs when grid is already available and Victrons are waiting/checking to reconnect.
So maybe thats "as intended"

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Alexandra avatar image Alexandra ♦ n-dee commented ·
It seems like they are frequency shifting. Usually when a pv inverter has been programmed in the ESS assistant it does that.
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n-dee avatar image n-dee Alexandra ♦ commented ·
Yes that's what i thougt. I've got a Fronius in microgrid-setting.

Maybe the victrons do that to shut down the fronius until the victrons are reconnected to the grid.


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dennibu avatar image dennibu n-dee commented ·

Die Victron tun dies ganz bewusst, da der Output wieder mit dem Input synchronisiert werden muss. Um zu verhindern, dass die AC-PV den Strom bei Annäherung an 50 Hz wieder einschaltet, wird die AC-PV zunächst bei 53 Hz abgeschaltet.

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jeroen-kuijf avatar image
jeroen-kuijf answered ·

Good afternoon,

Check this topic,

Multiplus and Quattro frequency shift too slow!

Maybe there you can find what is happening as I had the same at that time.

It might be that you have to upgrade your firmware and/or your frequency shift parameters in your Quattro's and PV-inverters, then it should be ok as can be seen in this topic.

What also helps is to put Supercapacitors parallel over your batteries as close as possible to the Quattros DC connections, as you mention you went to bigger Quattro's but you didn't mention also bigger battery.

These Supercapacitors will reduce your DC ripple and give this well needed boost when switching something heavy.

With the very best regards, Jeroen.

https://vrm.victronenergy.com/installation/48664, www.quintacasadafonte.com





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n-dee avatar image n-dee commented ·

What do you mean with upgrade your frequency shift parameters in your quattros?

(btw. i've got multiplus II, all firmwares on last official release)

Maxwell 48v 165 Farad ultracapacitor... very expensive...


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jeroen-kuijf avatar image jeroen-kuijf n-dee commented ·

Good afternoon,

I presume you have PV inverters on the output of these Multis, right?

In your assistants you can alter PV inverter support, standard 50.2Hz, 52.7Hz and 53Hz, PV installed inverter power and installed PV power, as so you can also change these frequency parameters in your PV inverter.

This assistant must be placed on the last position in the list! very important!

With sudden PV power changes (cloudy and the batteries almost full) the Multis will prepare themselves and you can see this frequency go up and down to keep the charge voltage below the limit.

Yesterday I checked my system, the reaction time is about 2-3 seconds 1Hz, so the little movements of 49.9-50.1Hz, I see also sometimes, not always, only at the beginning of the PV reduction and at sun down (cloudy and/or battery full).

Might this help you?

With the very best regards, Jeroen.

https://vrm.victronenergy.com/installation/48664, www.quintacasadafonte.com

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jeroen-kuijf avatar image jeroen-kuijf jeroen-kuijf commented ·

Good afternoon,

I've checked again, and indeed on VRM and the Cerbo it is flicking between 49.9-50.1Hz but my frequency meter on one of the phases not, bang on 50Hz all the time.

So, no worries, it's just a coms glitch from the Multi to the GX device.

Maybe you didn't notice that before on your "old" inverters and GX.

Murata DMR20-1-FM, frequency meter, very handy and easy to mount.

With the very best regards, Jeroen.

https://vrm.victronenergy.com/installation/48664, www.quintacasadafonte.com

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