ESS fails if one phase is down

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fli037 asked Nov 19, '23

ESS fails if one phase is down

I have a 3 phase ESS setup with 3 x 5000 VA Multiplus 2, 1 MPPT, 1 Fronius ongrid inverter and a Pylontech battery bank of 20 kWh.

If one of the phases fails then the ESS system switches over to inverting mode feeding the whole house from battery. Even though the other 2 phases are present the ESS will ignore them and run the battery down to SoC then blackout the house.

From my research this is a common problem where 1 phase goes out of specs and has not been solved by Victron (found posts from 2022 describing this issue)

My ideea is to add an Automatic phase selector device that I have already purchased in the past (https://www.novatek-electro.org/pef-301/). This device gets a 3 phase input L1 L2 L3, monitors the phases and outputs 1 phase 230V, the most reliable one.

From this phase I plan to feed an aditional Multiplus 2 3000VA that will only feed the 48V bus bar to charge the battery bank.

Plese see bellow arrangement where the red lines represent the newly addition to the system.

Any toughts on this solution ? Could it be integrated in ESS to be last priority to charge batteries ?

Automatic phase selector

ESS

ess-with-multiplus.png (286.1 KiB)

phase-selector.jpg (15.6 KiB)

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Modifications Space

Node Red Space

Answer 1 · 2023-11-19T14:39:09Z

nickdb answered · Nov 19, 2023 at 02:39 PM

PV inverters complicate things a little.

You could experiment with disabling the “switch as a group “ option in the ve bus configurator as well as changing phase regulation from total to individual, in ESS settings.

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fli037 commented · Jan 20 at 04:12 PM

disabling the “switch as a group “ will disable ESS

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Answer 2 · 2023-11-20T08:30:53Z

fli037 answered · Nov 20, 2023 at 08:30 AM

Yet again AC Input shows disconnected although my on grid Fronius solar inverter functions. Could it be a malfunction of the ESS. I am not on site to check with the multimeter.

Could be something to do with the grid settings in the Multis ? Is there any time delay to recconnect back to the grid if the grid fails for a short while ?

My Shelly smart meter reads that all pahses from the grid are on and I am exporting some energy, while Victron ESS shows no grid.

1700468980414.png (47.7 KiB)

1700469266109.png (52.1 KiB)

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Answer 3 · 2023-11-25T04:01:11Z

andrew-doroshenko answered · Nov 25, 2023 at 04:01 AM

I think you can't use automatic phase selector with Victron inverters. Because, when voltage appears at the input, phase synchronization occurs before the internal relay turn on.

The proposed "automatic phase selector" will instantly switch the phase without delay, which will lead to a potential difference between L Ac in and L Ac out, which can damage the inverter. This is why the inverter's internal relay does not immediately turn on when AC in appears.

I think switching is possible if delayed. It takes time for the inverter to understand that a phase has disappeared, and then to appear, so that the algorithm programmed by the manufacturer works correctly.

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fli037 commented · Jan 20 at 03:31 PM

The phase selector that I am thinkig to install will only feed in a separate single phase Multiplus 2 used as in charger mode only and output 48V to the batteries.

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Answer 4 · 2024-01-20T15:12:42Z

fli037 answered · Jan 20 at 03:12 PM

I can see there are some more discussions on the same setup:

https://community.victronenergy.com/questions/73505/3-phase-multiplus-ii-ess-system-with-an-additional.html

If I remove "switch as a group" option then the ESS is not possible anymore. There are many threads on the same issue and there is no solution to this yet.

I will need to try to get 1 phase out of 3 with the phase selector I have and feed a 230V - 48V DC Multiplus 2 3000VA used as a battery charger only.

The question is if this multi used as a charger can communicate with ESS and Pylontech BMS and adjust the charging current as required ?

It also need to function only when AC input to ESS is malfunctioning. This could probably be done through Red Node.

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