I’ll really appreciate assistance, been going at this problem for over a year.
90kVA Quattro’s, 3Ph system, 2x15kVA’s per phase.
140kWh battery system.
50kW/63kVA 3Ph generator.
Grid-tie Fronius, and 450/200 MPPT DC coupled PV.
Load is average 15-30kW.
There is no Grid.
Gen connected on a 160A 3Ph breaker. Downstream of the breaker I take the Gen power to AC In 1 of each inverter (It was on AC In 2 as I try to fault find, same problem it makes no difference, currently on AC In 1).
The problem:
THE GEN DOES NOT SYNC. There’s multiple threads on here about the same problem, I’ve tried most of others’ solution but never got this one to work.
Sometimes the Gen will sync for 0.5-1 sec and then the inverters reject it.
Other times it just doesn’t accept it at all.
Other times it accepts it for 5-10 seconds and then rejects it.
Other times it accepts it for 1-2 minutes and then rejects it and the Victron trips.
I get no errors. When the Victron rejects the Gen there’s a warning on the GX but it only says no Gen input detected (Gen is in fact there, but the inverters reject it and then the warning pops up).
Gen frequency is perfectly in range, I’ve even had a Gen specialist there to fine tune it with and without load, it’s perfect with 50Hz. No load it sometimes drops to 49.6Hz, but mostly runs on 50Hz. That’s better than our local grid!
Input settings has been changed and played with multiple times, over and over. Wide voltage window. Ground relay on and off, dynamic limiter on and off, input currents high and low (Currently on 10A), Grid code is on none but I’ve also tried some grid codes. Battery charge current normal (200A-default), but I’ve lowered it to 20A thinking it’s the chargers, but still a problem. I really don’t know what else to test to get this right.
I’ve switched off the Fronius inverters thinking it might be disturbance from them, makes no difference.
Aren’t you concerned about the input data at the point of synchronisation, as well as the resulting phase load imbalance and the voltage and frequency sag? I think the answer is pretty obvious and staring everyone in the face.
Personally, if the genset does not have active frequency regulation, i would set no-load frequency a bit above 50Hz, 50.5 or even 51Hz, so that at near full load it will be around 50Hz.
Is the generator starpoint earthed? Or did you create a centralized N-PE connection upstream? Since there needs to be an N-PE connection in the system at all times, otherwise L-N voltages can skew. The moment the ACin relays switch on, the internal N-PE relay is switched off, so the generator star point is now responsible for the N-PE connection.
In all the videos the AC PV looks to be not outputting power, is it switched off on the hardware side, or solely because the victron system sometimes goes to 53Hz which then drives the AC PV into a soft shutdown?
Since its mostly L2 and L3 saying “not in sync” first, how are the phase angles, both in the island and the generator? Yes in theory they should all be 120°, but if consistently two out of three inverters say “out of sync”, then theres got to be some discrepancy. I would be surprised if its on the genset side, since the phase angles are determined by the physical generator windings, but who knows.
The victron system sending power back to the genset on two phases might also be because of this. The phase angles are merely in range, all ACin relay connect, but two phases are off by some degrees, resulting in power flowing back to the genset.
Also, i never really payed attention in other systems, is the “ignore AC” changing to 1 a reaction of the system itself to the L2 and L3 inverter going out of sync, or the other way round? Is there something in your setup that switches “ignore AC”?
The Quattro’s put a massive load on the Generator, even with the input current limit low and dynamic current limit on. I think with the load spike those voltages and frequencies dip yes, but recovers quickly after. I’ve also lowered the charger current a lot, thinking that’s what’s causing the big load, but doesn’t help. You’ll see sometimes it runs for a few minutes with no issues and then just cuts out with no load spikes. Unfortunately the VRM doesn’t record per second data so can’t see everything that happens, and I can’t find logs somewhere to see the reasons why the Quattro’s rejects the Gen, that would have helped a lot.
The Gen has a star point yes. We’ve played with the frequency a few times, for exactly the reason you describe, results stayed the same.
The PV is off mainly because I didn’t want the battery to charge up and then I can’t call the Gen.
We’ll need to connect a meter to confirm phase angles, valid point. As you state, shouldn’t be a Gen problem but should check it to cross off fault finding points.
No idea about the ‘ignore AC’ logic. The setting is unchecked in the settings. I can maybe also link to the downloaded VEConfig if that helps.
But is it bonded to PE permanenetly? That was the main question. Since once the system switches from the Quattros to the genset, the N-PE connection moves from the internal N-PE relay of the Quattros to the genset.
Or you have some other defined N-PE connection upstream, which is of course also possible.
That’s exactly what I’m telling you.
Your problem is your pathetic generator. It’s simply not capable of carrying this load.
The solution to your problem is a proper generating set rated at no less than 180 kVA.
Then the system will operate reliably. Generally, for loads like this, you should be using proper diesel generator sets with at least a 50% power reserve.
On one of my projects with a 150 kW load, we’re using a low-cost solution, an auction-purchased Caterpillar 300 kVA marine standby generator.
You could solve your problem with 2 (possibly 3) more 15kVa inverters. Thus avoiding buying a bigger generator.
Use them in charger only mode. They are connected to the generator and charging the bank directly.
No synchronisation necessary (or loads interaction) and bank charging happens.
Remove all main system connections to the generator unless you will only ever use it in pass through on the main system (in other words disable their internal chargers) incase of emergency or main system shut down.
Since you already like HA and node red, having that display or counted into VRM is not difficult.
Is the 3 fase rotation of the generator the same as the Victron installation? L1 and L2 of the generator right turning direction and L1 and L2 of the Victron installation al so a right turning direction?
