I have 3 MultiPlus-II 5000VA/48V/70A with 600Ah pylotech batteries and a 15kw solar installation with SmartSolar MPPT 250/100 and MPPT RS 450/200 in ESS mode and feeding into the grid.
I have 2 problems:
-When we have a Residual current circuit breaker (RCCB) or Ground fault circuit interrupter (GFCI) at the grid input before the victrons it trips when the victrons are connected to the grid (we have tested various classes and various sensitivities, with and without grid dumping), if I just use a thermal-magnetic circuit breaker it works correctly.
-We have now bought a backup generator in case there is a grid failure and we run out of batteries and sun. It is a big 20kv generator, our consumption is about 4kw, so when the ATS system switches to the generator (and we manually deactivate the mains feed) it does not synchronise, the relays are heard several times making ‘click click click click’ but nothing else, the current it gives is good 230V and 50hz, we have done everything possible from the veconfig (Dynamic current limiter, limit the amps to 3, accept wide input frequency range, activate and deactivate powerassist, activate weak ac input).
I would not expect to use an RCB or GFI on the input to the inverters. GFI is best implemented on the AC out. The Multiplus grounding relay is not configured with a delay (probably due to the fast changeover of the multis - which is more useful).
I think you mean a 20kVA generator - not kV…
However, there are also some waveform requirements as well as voltage and frequency for the Multi’s to synchronise and connect to the Gen as an AC input. If you download the VE configure software (used for configuring the multi’s, then you can access the IP protection log in the grid tab, this should give you the reason for the lack of connection. sometimes with larger generators with AVR’s the generator may require some static load (water heater) before the output is clean enough for the Multi’s to connect.
Thanks for the reply, the generator is 20kVA, yes.
I have tried connecting loads (such as a water heater) and it does not work. Yesterday I made it work by deactivating the LOM and marking the input as generator, this way it always works, first time and without problem, I have removed the RCB/GFI from the inputs (both generator and mains).
I have put a mechanism to disconnect from the mains physically if there is no mains.
Deactivating LOM will make you not compliant to the grid code and result in potentially dangerous situations.
Generators and LOM detection are known to sometimes cause problems.
Info on LOM is here.
Your generator might have a bad impedance or earth.
Check if your generator’s Neutral is connected to earth (it should be) and it is properly connected to your system’s earth (they must be the same).
If you can’t make your generator work with LOM enabled, your options are:
install a Quattro instead of a Multi
install an external LOM detection device
Running ESS with a generator is tricky as well because you need to make sure that you will never feed energy into the generator.
-We are aware that it can be dangerous, that’s why we take the necessary measures.
-The generator is correctly grounded, the neutral of the generator is also grounded.
-We have detected that at the moment we change the AC1 input from ‘grid’ to ‘generator’ the same cerbo cancels the spills and adjusts the system for correct operation, this option is great, as we have automated it with nodered just when we activate the generator relay.