Multiplus and Hoymiles in AC coupling, frequency shifting worst case scenario

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carlosg asked Sep 16, '23

Multiplus and Hoymiles in AC coupling, frequency shifting worst case scenario

Hi,

I am close to buy a Multiplus but have a few questions:

-Is Hoymiles supporting frequency shifting to be used in AC coupling? I found some thread in german stating that NS protection (NA Schutz) is supported but not 100% clear to me: https://community.victronenergy.com/questions/182753/frequenzverschiebung-frequenz-shifting-bei-hoymile.html

Anyway if after the frequency shifting the generated power by the Hoymiles is not reduced, the Hoymiles shall disconnect when reaching 51,5 Hz, correct?

-If frequency shifting fails or is not supported, what is the Multiplus doing in case that the public grid is down, the Multiplus has already reached the 51,5Hz, the battery is full and some inverter is still on? Shutting down the AC OUT to force the inverter to switch off to protect the battery?

Thanks!

Multiplus-II frequency

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Answer 1 · 2023-10-31T22:49:13Z

honu answered · Oct 31, 2023 at 10:49 PM

Hello,

Also interested, planing on adding 2 strings to charge my car, in AC coupling , Hoymiles is one of my solution, APS an other...

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Answer 2 · 2023-11-01T06:09:54Z

stromesel answered · Nov 01, 2023 at 06:09 AM

You seem to have the same scenario like me (exept I plan to use a SolPlanet WR): https://community.victronenergy.com/answers/240251/view.html

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Answer 3 · 2023-11-01T15:21:25Z

aaxc answered · Nov 01, 2023 at 03:21 PM

As far as I know all inverters that are sold in Germany/Europe are conforming to DIN EN-50549-1.

And if you look at the https://www.netzfrequenz.info/aktuelle-netzfrequenz-full (German) you will see that all inverters will drop offline at 51.5 Hz.

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honu commented · Dec 06, 2023 at 09:46 AM

Dropping is not good enough, there is a need in AC coupling, dor a smooth transition between 100% power to 0% power and not a on/off attitude from the inverter.

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Answer 4 · 2024-05-14T09:33:16Z

hansdampf answered · 2 days ago

To answer the second question: if frequency shifting is not enabled or not supported by the pv inverter, the Multiplus will shut down as soon as the battery is full and the BMS reports over voltage. I can confirm this at least for my combination of Pytes Ebox 48100R-C connected to Multiplus II GX via CAN-BMS. Max cell voltage reported by the BMS was 3.655V and the inverter did shut down quick enough so that the BMS itself didn't have to cut off the battery.

But with EU and also German VDE 4105:2018 grid profile, throttling of Hoymiles inverters via frequency shift will not be possible from 100 to 0% because of high-frequeny shut down already 51.5Hz.

The default throttling rate (frequency watt droop slope) is 40%Pn/Hz (% of nominal power per Hertz) and throttling will start at 50.2Hz. So at 51.2Hz it will be 60% and at shut down frequency it will be 52% and 0% at 52.7Hz is never reached.

To be able to cover the full throttling range of 100% down to 0%, the slope needs to be set to 100, so 0% will be reached at 51.2Hz.

In order to set this up, Hoymiles DTU + installer account are required.

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