3-phase Quattro ESS: L2 stays in passthrough on-grid, works off-grid + abnormal rattling noise

[ledertom (Thomas Lederer)]

Hi everyone,

I have a 3-phase Victron ESS. It was working good for last few years but lately I am having problems.

My system setup:

• 3 × Quattro 48/10000/140-2x100
• Cerbo GX
• Pylontech battery bank, 720 Ah
• ESS: Optimized without BatteryLife
• Multiphase regulation: Individual phase
• Grid setpoint: 10 W
• Grid metering: Inverter/Charger
• Grid code: Germany VDE-AR-N 4105:2018-11, external NS protection
• External anti-islanding protection: Ziehl UFR1001E

It isnt working reliable anymore now. First, a fuse in the grid supply to the Victron system failed. The system continued running from battery until Pylontech reached about 5% SOC, which is fine since that is what I have in my settings.

I then switched the house to a direct grid bypass so the ESS was no longer supplying the loads.

After replacing the failed grid-side fuse and switching back to the Victron system, I also found that the L2 fuse on the AC output from the Victron system to the house had failed. After replacing that fuse, power was restored on all phases.

Since this event, however, the L2 Quattro behaves differently from L1 and L3 when the grid is connected.

With the grid connected, L1 and L3 behave normally under ESS and supply their loads from the battery or from pv voltage if there is any, while L2 almost always just is in passthrough/grid import.

The “Inverter” LED on L1 and L3 flashes normally while ESS is discharging the battery. On L2 it hardly flashes at all when the grid is connected.

If I disconnect the grid completely, all three Quattros switch to inverter mode (L2 also).

So the L2 inverter is capable of producing AC power. The problem only appears during grid-connected ESS operation.

The L2 Quattro has also recently become very much louder than L1 and L3.

It produces a mechanical/rattling or “knattering” noise which can even occur in inverter mode at almost zero load. L1 and L3 to not make such noice.

I have a video recording where the noise can clearly be heard.

After disconnecting and reconnecting the grid, the complete 3-phase VE.Bus system has often refused to reconnect to the grid for a long time. When looking at the cerbo here it shows correct voltange and requency for all phases but “Active AC Input is on DISCONNECTED”

The external Ziehl UFR1001E looked normal and both K1/K2 relays were active.

A VE.Bus “System reset” did not solve this problem. I then manually switched all three Quattros to 0, waited, and switched them back on one after another. After this full hardware power cycle, the grid was accepted again.

What I did already:

• 3-phase VE.Bus System Configurator check: OK
• Physical switch on L2: position I / ON
• ESS Assistant installed on all three Quattros
• L2 and L3 ESS Assistant configuration is identical
• ESS Assistant parameters:
  • LiFePO4 with external/CAN BMS
  • Battery capacity 720 Ah
  • Sustain voltage 48.0 V
  • PowerAssist unchecked
  • Lithium batteries checked
  • Dynamic current limiter unchecked
  • Storage mode unchecked
• Use AUX1 as disable FeedIn signal: unchecked
• ESS Relay test: Completed
• Pylontech CCL: 370 A
• Pylontech DCL: 370 A
• No relevant VE.Bus alarms
• Grid voltage/frequency normal on all three phases
• UFR1001E / external NS protection appears normal
• L2 successfully inverts when grid is removed
• A full hardware power cycle temporarily restores normal behaviour

I also downloaded the complete Remote VEConfigure configuration and compared the units. So far I have not found a configuration difference which would explain why L2 behaves differently from L3.

Any suggestions would be very welcome.

[Jeroen2 (Jeroen Kuijf)]

Good evening,

Looks like you had a big short circuit to the house when it was on grid.

Stupid question maybe, but, do you have filters installed?

You can check in VRM the alarms which occurred that time and also how much ampères you pulled (if you have that trend made), even you can make that trend and still retrieve that data.

The ratling sound looks like that some transistors or capacitors have given up, that you might be able to see if you make a VDC ripple trend in VRM for all 3 inverters and see the difference.

Also, sometimes it is not exactly producing the correct output voltage in battery mode only anymore, this, again is easy to see in an output voltage trend in VRM, then apply load to the affected inverter only and see if it stays in about +/-0.5V AC after starting that load, during start it might be +/-3.0V AC pending cos phi, etc.

But, as I said, find out first why you blew up fuses, as this might happen again soon, then test by these trends you have or can make easily as described above, and then, let them see here so we can help you asap, as it looks you most probably need to make a repair.

Regards, Jeroen.

[ledertom (Thomas Lederer)]

Hi Jeroen,

thanks for your reply. I checked the history in VRM and found a few things.

The blown fuse was most likely not caused by a short circuit. We have several large machines and normally do not run them at the same time. However, that time now we did it… The fuses are only 35 A per phase and when running this multiple machines it was to much for them. There were no overload or short-circuit alarms from the Quattros.

More importantly: I checked the L2 history further back and the abnormal behaviour was already present for several weeks before this fuse event. So I think the fuse event is probably unrelated and only made us notice the problem.

The main issue is still that L1 and L3 regulate normally in ESS, while L2 stays completely in passthrough as you can see in the attached figure from the last 30 days for L1 and L2… L3 looks similar to L1 so I did not attach it, but if you need it than just tell me so I can send it to you as well.

I also tried the VDC ripple trend as you suggested. VRM offers “VE.Bus Voltage ripple - unit X” and “VE.Bus Terminal voltage - unit X”, but I get no data for any available unit number. Is there another way to read the ripple per inverter live?

I found a historical period where AC input was definitely disconnected and compared the output voltage of all three phases. I do not see a clear difference on L2. The ranges were approximately L1 227–236.5 V, L2 225.8–236 V and L3 224–236 V. If I should send the pictures from that as well than please just tell me.

I would prefer not to disconnect the grid deliberately again because I also have an intermittent problem where the system sometimes does not accept the grid again afterwards, even though about 230 V / 50 Hz is present on all three inputs. A full hardware power cycle of all three Quattros restored it.

The rattling/mechanical noise from L2 is still present and can occur even in inverter mode with almost no load. L1 and L3 are much quieter.

I do not have any additional DC filters/capacitor banks/chokes installed.

Do you think the noise and the strange grid-connected L2 behaviour could be related to an internal hardware problem?

Thanks a lot.

Regards,
Thomas

Actually the last time, it really was “giving something back to the grid” was around end of july, so I guess it doesnt have to do anything with the fuse… this just made me recognize the problem…

thanks a lot for your help

[Jeroen2 (Jeroen Kuijf)]

Good morning,

What a mess that phase input 2.

I would contact your energy supplier and see what they can do to start with.

I bet that when you put that graph in detail you will be even more surprised how low and high that voltage swings.

What you can do in the meantime, on the input to the inverters you have a breaker installed, phase 1/2/3/N, switch off, switch the wiring 1 to 2, 2 to 3 and 3 to 1, the phase rotation stays the same in that way, now this bad voltage goes to inverter 3, test if inverter 3 makes the same sounds due to that bad voltage and if inverter 2 is now quiet.

If inverter 2 is still noisy and inverter 3 is quiet, then its not the input voltage, and a repair/check of inverter 2 might be needed.

Regards, Jeroen.