question

piet-skiet-verniet avatar image
piet-skiet-verniet asked

Multiplus feeding power back into grid

I have a multiplus 48/3000/35-50 inverter with a battery pack acting as redundant power for a server room. I have a problem where when the site is running on generator power, the inverter is apparently feeding power back into the grid (the "grid" wattage goes negative)

When this happens, the inverter throws overload warnings and will sometimes throw an alarm and disconnect my loads. (production servers) Once this happens, the power on the inverter needs to be cycled.

The load is relatively small at this point (300W) but the grid/genset is very large (100s of kW)

How do I configure the inverter to not transfer power back into the grid under any circumstances?

MultiPlus Quattro Inverter Charger
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Alexandra avatar image Alexandra ♦ commented ·
@piet-skiet-verniet

A few more details are needed. Do you have solar is it an ess system? Is it happening during charging?

Maybe try running your grid set point up a bit higher.

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piet-skiet-verniet avatar image piet-skiet-verniet Alexandra ♦ commented ·

Thanks for the reply, Alexandra.

There is no solar system at all. There is also no ESS setup that I'm aware of.

It is just the multi (Product ID 2620 running firmware 405 which I'm aware is quote old), a BMV-600S and a Color Control GX (firmware 2.72)

It seems like the Multi is allowing export to the grid when it should be configured not to, or there is some kind of electrical issue on the grid that is causing the inverter to overload.

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Alexandra avatar image Alexandra ♦ piet-skiet-verniet commented ·
@piet-skiet-verniet
It would seem then the output of the generator is connected to the load side of the inverter so feeding back into the unit backwards rather than through the unit.

A small troubleshooting step would be to disconnect the ac in on the inverter and run the generator and see what happens then.


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piet-skiet-verniet avatar image piet-skiet-verniet Alexandra ♦ commented ·
I have done this test before - it does work fine when isolated from the grid.

I have read some other posts on this forum and it seems a firmware update may resolve this issue.


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Alexandra avatar image Alexandra ♦ piet-skiet-verniet commented ·
So when the inverter is disconnected from grid and the genny is running, how does it affect loads on the inverter?

There is most likely a mixed or borrowed neutral connection somewhere.

Does the inverter make a noise like a relay buzzing/clicking when it is overloading with the generator on?

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piet-skiet-verniet avatar image piet-skiet-verniet Alexandra ♦ commented ·

I'm usually not around the inverter (its a remote site) and it has never been running on generator while I was there. I will see if I can get in front of it while the site is on generator power again.


The output power graph looks a lot noisier when the generator is running. The typical input RMS voltage is around 245V when on utility grid but this drops to around 230V when the on generator.

This is an industrial site with a lot of very noisy high-powered loads.


In the picture below you can see when the site switches from util to genset at around 03:00, then back again about 8 hours later. It seems as though the overload alarms coincide with the input current going negative. (ie: feeding current into the grid)

vrm.png

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vrm.png (140.0 KiB)
Justin Tierney avatar image Justin Tierney commented ·
I have a different setup but seem to be having this same issue. Multi ii fw491 and back feeding. It’s currently unusable, not sure the next move.
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7 Answers
shaneyake avatar image
shaneyake answered ·

I have had this problem before.
It was fixed with the firmware 481.

The other thing to check is that the grid code settings are set to No DC.
You can then adjust the change over voltage. I found going from 180v to 200 or 210v which get the inverter to disconnect before it had to deal with any input power problems. I also tend to lower the upper voltage limit to 250v, as remember to have at least 8v between disconnect and connect voltages.

The issue you are most likely seeing is that the inverter is unable to track the incoming voltage correctly and this can cause really high currents in the inverter which causes an overload.
This tends to happen if input is very noisy in both voltage and frequency.

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Alexandra avatar image
Alexandra answered ·

@piet-skiet-verniet

Shaneyake is onto something there.

Other than a firmware update. Possibly a lom setting is the issue there, the backfeed relay is misbehaving.

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piet-skiet-verniet avatar image
piet-skiet-verniet answered ·

Thanks folks. It looks like I should start with a firmware update on this inverter.

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piet-skiet-verniet avatar image
piet-skiet-verniet answered ·

I have not upgraded the firmware yet (need a vendor to assist), but I have gotten the VEconfig data from the unit and I see the "grid code standard" is set to "other".

its a Multiplus (not II) with firmware version 406. The only options i see for grid are UK, Itally, "other" and "none".

There are no settings for LOM at all. Is it possible that "Other" will feed back into grid or are there other settings I can check to confirm that?

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JohnC avatar image JohnC ♦ commented ·

@piet-skiet-verniet

Select "None" as a grid code. You'll get this in VEConfig..

1631876716861.png

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ludo avatar image
ludo answered ·

I updated my Multiplus 12/3000 from 2609430 to 2609497, now all seems fine......at least for the last 30 minutes ;)


Sadly enough VEConfigure said my firmware was up to date, I should have checked earlier

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Matthias Lange - DE avatar image Matthias Lange - DE ♦ commented ·
VE.config can't check for updates for the MultiPlus.

If you use "options -> check for updates" it only looks for VE.config updates not for the connected MultiPlus.

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ludo avatar image
ludo answered ·

I had a message from Bob Hopman stating the default setting "none" should not be used, the Multiplus should be set to Germany / VDE and keeping AUX1 disconnected to disable the feedback.

I wonder

a.) why this setting exists if it should not be used

b.) why all of this is not included in the manual that is supplied with the unit. A referenc to the ESS-manual is useless, why should I read this if I am not planning to use the feature ?




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Alexandra avatar image Alexandra ♦ commented ·
@Ludo
The none is there for some of us out there who use it.

The grid code is usually set for where you live. Not every country has a standard set for ESS and are allowed to use it. Or feedback anything to the grid.

Also there are mobile installations that don't use ESS.

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ludo avatar image ludo Alexandra ♦ commented ·
Bob Hopmann of Victron explicitely told me 'none' should not be used, instead I should use 'German' and disable feedback by blocking input Aux1.


I have a "mobile installation" i.e. a Spartan motorhome, ofc I don't use ESS.


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ludo avatar image
ludo answered ·

So, now I installed the oldest firmware version available for my device : 2609159 and now all my problems seem to have vanished. This Version had no adjeustments for "Grid", so I guess it will not support feedback.

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