question

motylu avatar image

Multiplus-II grid protections and feed-in control in 3-phase configuration

Hello guys,

I am from Czech Republic and planning to use 3x MultiPlus-II 48/3000 in 3-phase configuration and DC coupled system with PV array (2 strings, 2 MPPTs) and Pylontech batteries.

Of course I will set grid code to "Europe (EN50549-1:2019)" and there are several options for over/undervoltage and over/underfrequency protections, conditions for normal connect and reconnect after trip, controlling power according to frequency and voltage and also option for use Aux 1 input as feed-in disable signal. Setting of all protection is clear for me but our electric distributor have several requirements for connecting "micro-generators" (PVE with P < 10 kW) to the grid, so I have two questions about grid code functionalities especially in 3-phase mode:

  1. If the condition for activating grid protection on one Multi is met and therefore AC input of Multi must be disconnected from the grid, is then automatically disconnected all Multis from the grid?
  2. I want to use disable feed-in using Aux 1, because our distributor must be able to reduce power feeding to grid (for these micro-generator only two states: 100% and 0% feed-in). My question is how disable feed-in function is realized in practise on Multis and whether I must used Aux 1 on all Multis (for example with 3-pole relay, each pole for each Aux 1) or if is sufficient to use Aux 1 only on one Multi (probably on phase L1) and feed-in will be automatically disabled in general for all Multis?


Thank you very much for your answers.

Multiplus-IIgrid3 phase
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3 Answers
Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

1. All will disconnect from the grid.

2. The signal is only needed at the master (L1).

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motylu avatar image
motylu answered ·

Thank you very much for your quick response. Function is as I expected, so it will be easy to implement!

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motylu avatar image
motylu answered ·

How to set up all Multis in this configuration with control relay connected only to Aux 1 of master (L1) Multi?

I will add ESS assistant to all Multis, change grid code on all Multis and what about setting of Aux 1? Set Aux 1 for disable feed-in on all Multis together with connection only Aux 1 of master Multi? Or set it only on master Multi?

And is it possible to connect Aux 1 on all Multis to one 3 pole relay, set disable feed-in on all Multis - as backup, if there is a problem for example with one pole contact of relay or Aux 1 input of master Multi?

3 comments
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With the correct Grid code applied, AUX 1 will trigger the the system to stop exporting.
You can just put the same settings on all units but you only need to trigger the AUX 1 input of the master. It will disable feed-in on all mults if master is triggered.

Many thanks for your answer.

So this means that trigger AUX 1 of master Multi will disable feed-in on all Multis, it is definitely clear.
But what about trigger AUX 1 on slave Multis? This will not disable feed-in anyway? I am thinking this way only for redundancy control as backup in case of problem with AUX 1 on master Multi, because I have spare 4 pole relay…

I am not sure, probably ignored. I however wouldn't do it as this isn't' the intended install method and you might get some unintended results.