question

Marco Nijholt avatar image
Marco Nijholt asked

Maximize grid charging with unbalanced loads in 3 phase setup

Hi everyone,

I'm using my victron setup to utilize dynamic energy prices, that means depending on the day, i need to maximize charging my 50kwh battery bank in as least amount of time as possible to save the most money.

Now i'm running a bit into an issue where if 1 phase is loaded by a critical load, it will currently limit that phase for charging, which makes sense. However, it also reduces the charging speed of the other phases.

As you can see in the image below, the system is not maximizing the grid capacity to charge the batteries. Phase L2 has a significant load, and it’s perfectly utilizing that phase to its max capacity by running round 24-25A (grid breaker is 25A).


However, L1 and L3 still have capacity leftover, i'd like to utilize that however i seem to be unable to do this in this scenario.


1673403976931.png


When the large imbalance from the phase loads is gone, it does manage to overall pull more from the grid. And L1 and L3 seem to go to around 22-23A.

Here you can see when L1 and L2 have a high load, they are both doing the full 25A, but L3 seems to under compensate by only pulling 16A

1673404840603.png

Multiphase is set to total of all phases. Changing it to individual phase does not change the behavior.

Is there any reason why it does this?

Using 3x multiplus II 10kva 230v running ESS assistant


Multiplus-II
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1 Answer
michaelvh avatar image
michaelvh answered ·

Not an answer to your question, sorry, but I experienced similar behaviour in reverse (so not while charging battery from the grid, just using the ESS system)

This is the scenario:

- A large unbalanced load on one phase reaches the max amperage of the grid breaker (was 16amp in my case), the ESS system starts assisting the grid on that phase to the limit of 16A, as expected.

=> the other 2 phases start being assisted the same surplus, effectively draining the ESS battery in to the grid, which is not expected. In your case the other 2 phases get the same limitation.

Unfortunately i have no solution so far but I believe these two behaviours are related (as to how the power flow gets calculated)

The only workaround I can think of right now, is to actually get a larger breaker on the grid side, if your grid and cabling allows it, and change that setup in ESS assistant.

41598-img-5555.png

https://community.victronenergy.com/questions/163509/3-phase-ess-unnecessarily-feeds-the-grid-when-phas.html


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