AC-In lost and Multiplus 2 drain all battery with no loads!

DIY
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1

Hi All,

Something strange happened today at 4am till 7am.

Grid was lost due to earth leakage in outdoor socket (number 2 in image…rainy days), so multiplus 2 3KVA also lost the grid sync, since house protection differential (Number 1) was triggered.

During this period, there where no loads connected to ac-out 1 neither ac-out 2 (system is not yet finished/connected to work as UPS).
AC-in also was down due to grid lost (I can also confirm this, cause internet, Shelly EM, NAS, fridge etc was down )

At 4am battery SOC was 70%, and at 7am (when problem was detected) it was already in ESS #1 (minimum SOC 20%).

Multiplus 2 fan was running, and multiplus 2 was warm.

I am assuming MP2 got a software glitch when grid went down and all those KW (+/-10KW @3kw/h) where drain by the multiplus it self (mosfets got crazy by software glitch?).

Can you share thoughts? Where did 10Kw go if no loads where connected?.
Is this the first time someone reports this type of glitch?

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2

More data:
We can see AC-IN Power being “produced” till the minimum SOC of 20%

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3

Even though grid measure is done with shelly EM (have one ET112 but no time yet to install it :frowning: ) , after grid loss, and shelly going down, the script reports 100W.

That should not be part of multiplus starting to invert with grid loss with no loads.
I have ESS to keep 100W from grid…so even that is ok to let multiplus not need to invert as 100W is reported even with grid fail.

Any ideas?

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4

Are you sure you configured the right grid code?

Looks like anti islanding didnt work

5

I’m sure I have selected and uploaded the right grid code for Portugal:
(Portugal code is also EN50549-1:2019)

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Never failed before with that grid code.
I had version 45* (dont recall) in Multiplus 2, and last week I updated it to 552.

Maybe some issue related to version 552 (just thinking), since its the first time grid fails after this version installed, and the result was not the expected one.

As soon as I get home, I will disconnect grid and watch MP2 behavior.

And if symptom is the same, I will try some VDE code , just for testing.

6

Any other suggestions to verify?

7

Sorry for necro-posting but i’m curious about this issue. Isn’t it the case that when AC/IN trips the Multiplus supplies power to your other running loads by injecting through AC/IN? AFAIK it does that besides supplying through AC/OUT1 and AC/OUT2

8

Hi Luis,

I already changed all my connections and now I have grid going to ac-in and all loads/house, going into acout1.
I also removed shelly for grid and PV inverter (MP2 will now read grid, and for PV inverter I installed one ET112).

Regarding the old issue, I am almost sure, 2 things have happened. (Its hard to explain with text).

1 - With grid lost, shelly EM (script) does not clear the last known values to “unavailable”, so it showed 100 watts being draw from grid (lets assume 100watts).
2 - Even though ac-in relay was open, GX was receiving (script running) 100W in ac-in.
Since my “grid set point” is 50W, MP2 started to invert from baterry to AC-in to lower ac-in back to 50W.

Since there is no loads in ac-in (relay open) and no loads in ac-out (ports not used), and shelly EM is “locked to 100W”, MP2 started to invert more and more till its maximum rated inverted power to overcome those 100W and try to lower them to 50W (grid set point).

So where does that power goes if MP2 was like an island?
Well the only explanation is power draw by mosfets them-self’s.

I cannot replicate this, as my electrical system was changed as stated in the beginning of this message.

I assume Victron will not try to replicate this in their labs, since scripts and shellys are not supported.
Energy meters supported by Victron (USB, ETH, RS485) all need mains power (L-N), so when grid is lost, communication goes down and GX Software cannot see/read meters .

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But with scripts, even with grid lost, GX still continues to read energy meters as the script keeps running (there no power lost in scripts :slight_smile: ).
When power went down, also network was lost, so the script couldn’t update values either.
Thats why with power loss, values from grid meter stayed the same value.

To overcome this..yes buy a ET112.
Script is not very well coded…something is missing… in my opinion.

You can do the test:
Power down wifi/lan and check if script will keep running with last known value.
It will create a log with connection problems, but Remote console will still display last transmitted value.

Should Victron stop a grid meter script when grid is lost (or change value to unavailable)..probably.

Those are my thoughts in all this issue.

9

Cool, thanks for the followup comments

10

No! That would be dangerous, only ac out 1 is powered ac out 2 can be powered too when needed