question

bigkiss84 avatar image
bigkiss84 asked

Bug: ESS working correctly? 51Hz AC in -> Battery Charging

Hello,


I have been running an ESS consisting of the following components for about 3 months:


- EM24

- 3xMultiplus 5000

- 1x Fronius Symo 10.0 (connected to ACout)

- 45kWh battery


Everything was working fine until our network operator carried out maintenance work today and as a result the frequency in the local network was increased to 51 Hz. (at AC IN)


The Multiplus 5000 immediately began charging the battery from the mains. Although several consumers in the house should actually draw their energy from the battery, the entire house was supplied from the local network.


Is there a configuration error in the ESS?


Thank you


Best regards


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battery chargingESS
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lifeingalicia avatar image lifeingalicia commented ·

Hi should work except if input frequency range is set to disabled. (tab grid)

Accept wide input frequency range (45-65Hz): The MultiPlus accepts frequencies from 45 to 65Hz (default = enabled). If the generator is extremely stable and if that same stability is required on the output of the MultiPlus, this setting may be disabled.

https://www.victronenergy.com/media/pg/VEConfigure_Manual/en/grid-settings.html

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bigkiss84 avatar image
bigkiss84 answered ·

The “grid code“ is set to „Germany with internal NS protection“.

This means from >50.2Hz my ESS should stop Energy production step by step.

This function is correctly working because my Fronius was just producing 300W.

But it should never charge the Battery from the mains?! Especially if there are still 72% energy left in the Battery. The hole house should be powered by battery storage. Even charging was just limited through my CVL. After increasing the CVL all 3 MPII started charging with Full Power. Battery life is disabled…

Thank you for your support

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Alexandra avatar image Alexandra ♦ commented ·

@BigKiss84

The Fronius will be throttling at 51hz. You can check in it's widget on advanced or in its own site logging state

You may need to look at conditional connection and disconnect to AC to make more use of your ac solar.

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bigkiss84 avatar image bigkiss84 Alexandra ♦ commented ·
Hello Alexandra,

the throttling was working perfectly. Of course after disconnecting the 51Hz to the AC In, my ESS started discharging the Battery to consume the energy for the household.

I am sure that 51Hz is very unlikely in our European (german) grid but due to maintenance, they use 500kVA aggregates to temporarily disconnect the local transformer. The frequency is set to 51Hz to avoid damage from the solar power of all households in our little village to the aggregate.

My Multiplus are all set to german grid code. With this setting, it should not be possible that these devices start charging the battery itself, just because the Frequency of the grid was risen to 51Hz. For my understanding this is a kind of software bug and not conform with german grid code settings.

regards

Thorsten

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gerard-van-seventer avatar image
gerard-van-seventer answered ·

Since you have a German grid code I assume you are in Germany or one of the neighboring countries (like me) it is highly unlikely that the grid is at 51Hz. In the EU the grid can be +/- 0.1Hz but even that is very rare.

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bigkiss84 avatar image bigkiss84 commented ·

:-)

bildschirmfoto-2023-08-10-um-091358.png

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sesshoumaru avatar image sesshoumaru commented ·

I understood that the power company works on the transformer. They disconnected the public grid and do feed the local households by a huge generator which deliberaly has been set to 51Hz to stop the solar systems from trying to load the generator. So its a temporary local island.

I guess this is just not considered in the implementation, thus the loading logic goes haywire. Its probably not a bug, but "just" a not considered use case. But its worth adding it. Imagine how an entire area gets black started after power out.

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bigkiss84 avatar image bigkiss84 sesshoumaru commented ·
yes you got it. This is how it happened here.

If the local grid has a frequency of more than 50.2Hz in Germany (due to maintenance work), the ESS should still use the battery power until the minimum SoC is reached. And it should never charge the Battery automatically from local grid. (with german grid code settings).

I hope that someone of victron technicians read this :-)


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baxter avatar image baxter bigkiss84 commented ·
@mvader (Victron Energy) @Daniël Boekel (Victron Energy Staff)
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bigkiss84 avatar image bigkiss84 baxter commented ·
Hello @mvader (Victron Energy) @Daniël Boekel (Victron Energy Staff)

did you see my Bugreport?

Thank you.

Regards from Germany.

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nickdb avatar image nickdb ♦♦ bigkiss84 commented ·
This is such a niche use case, to cater for a temporary problem. Considering the long list of projects requiring dev work, I wouldn't hold your breath about this being looked at anytime soon.
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