Reduce Power of AC coupled PV - Frequency coupling

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max-payne asked Mar 18, '24

Reduce Power of AC coupled PV - Frequency coupling

There is a big Question with Blackout and ESS. What if battery is full and sun is shining and there is no grid to export to. The system otherwise is correctly spec. with 1:1 rule and appropriate kwh/wp installed.
Question:

Is there a compatibility list of PV Inverters that support frequency power reduction? I cannot find this in any manual - mostly min and max frequency is given in Fronius and Solplanet Inverters.

Fronius Dynamic Power reduction is something else entirely. I only find the working range of inverters. LAN GX connection is not what I want this should work with generic PV Inverters.

For example Fronius *should* turn off with 66Hz. But I dont see it would reduce power at 55Hz.

I cannot find which AC coupled PV Inverters reduce output if the frequency is above a certain range.

There is a sentence in the manuals:

Note that although the MG50 for instance has a higher start frequency of 51Hz, there is no real drawback using the proposed value of 50.2Hz. The system will just increase the frequency until the PV inverter regulation kicks in. The value of 50.2Hz will work with a broader range of PV inverters/grid codes.

Question 2:
This makes me assume that no matter what PV Inverter is connected: In the case of a No Grid + Battery full situation a 3 Phase ESS should increase the frequency until the PV comes offline with the ESS assistant? Am I correct?

battery charging ESS solar frequency

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max-payne answered · Mar 18 at 06:56 PM

If anyone comes and sees this here is the answer! If your PV Inverter really adheres to your grid code (which I am not sure chinese ones REALLY do - but brand ones will) here is an example for what that looks like:

Yet the producer of some PV Inverters (here Solplanet) will have this disclaimer.

So the answer is that when the multiplus creates a proper grid (3 Multi ESS) and the PV Inverter does adhere to the frequency scaling defined in your grid code (which you need to lookup) everything will work as defined in the ess assistant!

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Modifications Space

Node Red Space

Answer 1 · 2024-03-18T12:34:41Z

duivert answered · Mar 18 at 12:34 PM

hi, it hink you should read this, the disconnect value in your picture is way to high

https://www.victronenergy.com/live/ac_coupling:fronius

every inverter that is setup with the right grid code use frequency shifting to throthle down

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max-payne commented · Mar 18 at 04:23 PM

You didnt answer my question. Let me rephrase: Are the Fronius suggested settings applicable to throttle down generic inverters too?

Documentation Link as proof please.

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duivert max-payne commented · Mar 18 at 05:26 PM

Then the answer is No, settings are inverter/gridcode specific

For instance if the inverter is setup to VDE4105 gridcode then this would be the setting:

What is the idea of the VDE4105 standard? The idea of the VDE4105 standard is that the inverters are not abruptly switched off at 50.2 Hz (or above), but that the power is gradually reduced in small steps. This has given the grid operators an enormous amount of primary power that automatically stabilizes the electricity grid. Inverters that comply with this VDE4105 standard will reduce their electricity production slightly from 50.3 Hz and for every 0.1 Hz increase in the grid frequency, the power is further reduced in small steps. Ultimately, at 51.5 Hz the electricity production of the inverters will have dropped to zero.

Source: (dutch site)

https://zonnepaneelkiezen.nl/50,2-hz-probleem

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Answer 2 · 2024-03-18T17:31:56Z

duivert answered · Mar 18 at 05:31 PM

Also see:

- Most brands of PV inverters can be used for these systems, they need to be setup to support frequency shifting, often called the island-mode or micro-grid mode. For SolarEdge settings, see Integrating with SolarEdge, for Fronius settings, see AC-coupled PV with Fronius PV Inverters & for reading and controling ABB/Fimer inverters, see AC-coupled PV with ABB/Fimer PV Inverters.
- To read out SMA inverters, see AC-coupled PV with SMA PV Inverters.
Source: https://www.victronenergy.com/live/ac_coupling:start

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