Overload warnings on grid connection with Victron ESS regardless of load

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danepb asked Jul 27, '20

Overload warnings on grid connection with Victron ESS regardless of load

Good day All,

I have a Client running a Victron MP2 5kVAwith an AC coupled ABB 5kW unit what shows a daily overload warning. The thing is that there is no power outage at all, or a load to justify the warning in case of the overload. The base load is around 350W.

Yesterday the system turned off due to overload, but the inverter was drawing 50W from the grid and 300W from the batteries respectively.

I have several installs running this configuration with no indication of these warnings. The firmware on all the units are up to date with no high current draw warning from the pylon battery bank either.

I thought it maybe something to do with the grid inverter, however I have seen two warnings at night when the inverter is off.

Has anyone else see or experienced this or have advise on this matter?

Thanks

MultiPlus Quattro Inverter Charger

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nickdb ♦♦ commented · Jul 29, 2020 at 11:32 AM

I have the same issue on a 3kVA multiplus.

It generates an L1 exceedance even though L1 is nowhere near 32A with moderate AC1 loads.

The alarm clears almost immediately but I have not got to the bottom of the issue.

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Answer 1 · 2020-07-29T01:24:52Z

Guy Stewart (Victron Community Manager) answered · Jul 29, 2020 at 01:24 AM

Hi,

Specific to ESS systems, there are some causes of overload conditions related to the grid - please read the FAQs in the ESS manual here - https://www.victronenergy.com/live/ess:design-installation-manual#faq

Generally speaking in on and off grid systems, there is also training on diagnosing inverter overload here:

https://www.youtube.com/watch?v=4SXtGIx0x5w

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nickdb ♦♦ commented · Jul 29, 2020 at 11:33 AM

Unfortunately alarms don't contain any debug info to assist with what happened at the time.

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Guy Stewart (Victron Community Manager) ♦♦ nickdb ♦♦ commented · Jul 29, 2020 at 11:38 AM

Did you follow the information and links provided in Question 8 of the FAQ?

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nickdb ♦♦ Guy Stewart (Victron Community Manager) ♦♦ commented · Jul 29, 2020 at 11:43 AM

It doesn't help me. The inverter does not turn off, it is not inverting. L1 overload alarms are intermittently triggered (AC load is around 3000W but on grid). The alarm clears almost immediately and contains no useful data to diagnose. VRM (on a 1 minute interval) confirms no exceedances.

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Guy Stewart (Victron Community Manager) ♦♦ nickdb ♦♦ commented · Jul 29, 2020 at 11:52 AM

It is not intuitive, but typically in the case of 'overload on ESS, regardless of measured load' refers to the Loss of Mains detection being able to shift the AC input frequency due to high AC input impedance. The shifted frequency differential between grid and multi then lead to a large invisible 'overload' current.

Options to remedy are to improve the connection to grid (bigger, or shorter wires to your mains grid distribution board from the Multi),

OR

Adjustment of the Loss of Mains detection

There is more information here (that is linked from Question 8 of the ESS FAQ). That link details how to confirm if this is the cause of the issue, by temporary disabling the Loss of Mains detection, and seeing if the overload errors stop appearing.

NOTE THIS IS FOR DIAGNOSIS TESTING ONLY - an ESS system will no longer be legally compliant with the applied grid code if this is changed (without an additional external grid protection device). So a code which is available from your installer/distributor is required to make the adjustment.

It is possible that the grid is not so weak as to lead to a total shutdown overload, but just an warning. The diagnosis test will identify if that is the issue.

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nickdb ♦♦ Guy Stewart (Victron Community Manager) ♦♦ commented · Jul 29, 2020 at 11:56 AM

Thanks. Will review the info. This only started once ESS was enabled. The first time it happened, afterwards I went and turned on every appliance and there were no alarms triggered so that confirmed it was not a loading issue. The transient nature of the alarm (immediately clearing) suggested something else was going on. I had been focused on other issues and hadn't got around to this one until I saw this post.

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danepb Guy Stewart (Victron Community Manager) ♦♦ commented · Jul 31, 2020 at 06:39 AM

Thank you Guy,

I will give that a try.

Regards

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nickdb ♦♦ nickdb ♦♦ commented · Jul 29, 2020 at 06:17 PM

Had a few alarms tonight. Seems more likely to occur when there is a low power draw and then you turn on a high power appliance (iron, microwave etc). On grid it triggers an instantaneous alarm and alarm clearance.

The grid is apparently under strain but since vrm does not report frequency changes everything else looks ok.

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nickdb ♦♦ commented · Jul 30, 2020 at 10:26 AM

I think I am getting a picture of what might be happening here.

The inverter is choosing to first pull power from batteries instead of the grid, it then feeds in grid over a few seconds reducing the battery load, and when the load disappears it returns some charge to the batteries.

Unfortunately it seems happy to hit the inverter limit when doing so.

It should not be doing this when grid is available and it seems consistent behaviour in my environment when on a sched charge and there is insufficient PV.

I can't fault anything with the grid at this point, so why it is continually pulling battery power makes so sense and particularly in that amount, exceeding set ESS limits.

When changing modes to "keep battery charged" it does not do this but then I lose the ability to use my stored charge at night.

I have logged a case with support and the local distie to assist as currently it makes my solar install somewhat unusable.

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Answer 2 · 2020-08-17T08:13:25Z

dean-d answered · Aug 17, 2020 at 08:13 AM

We have a similar thing happening on two ESS installations. The grid in our area is a bit unreliable(power cuts), therefore customers want a backup system for emergency circuits.

If there is a power cut the system operates as it should. But if the grid gets weak due to high load on the network, then the Multiplus can go into overload and turn off.

The result is that there are more power cuts than there would be without the backup system installed.

We have tested the impedance of mains and subcircuits, which when tested are low. Under 0.5Ω

Although I'm not sure if this impedance jumps up during high load on the network and we are not there to test.

Would love a solution to this problem.

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Guy Stewart (Victron Community Manager) ♦♦ commented · Aug 17, 2020 at 08:31 AM

Hi @Dean_D,

There is a procedure here to confirm if the Loss of Mains detection is the cause of the issue, and some solution for what you can do to correct or workaround the problem for a reliable system :

https://www.victronenergy.com/live/ve.bus:grid-codes-and-loss-of-mains-detection

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dean-d Guy Stewart (Victron Community Manager) ♦♦ commented · Aug 17, 2020 at 08:43 AM

Thanks, @Guy Stewart (Victron Community Manager), Currently relying on the anti-islanding in the Multi. The issue is intermittent, so we would need to disable LOM for a week or two. Without external anti-islanding, I don't think we can do this.

Do you have any recommendations on an anti island device for New Zealand? if we do this test.

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Guy Stewart (Victron Community Manager) ♦♦ dean-d commented · Aug 17, 2020 at 09:26 AM

Victron stocks part number REL100100000 the Ziehl Anti-islanding relay UFR1001E

But the only way forward would be to talk to your grid supplier/distributor and find out what they are willing to approve.

A once weekly intermittent issue sounds frustrating indeed, most other cases I have seen have this occurring more frequently.

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nickdb ♦♦ Guy Stewart (Victron Community Manager) ♦♦ commented · Aug 17, 2020 at 11:09 AM

That Ziehl relay is seriously expensive, at least here it is.

For smaller installs it would be cost prohibitive being about 50% of the cost of a smaller multi.

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Guy Stewart (Victron Community Manager) ♦♦ nickdb ♦♦ commented · Aug 17, 2020 at 01:31 PM

As it is independent of the Victron equipment, the best thing to do would be contact the local distributors and see which products are available (and competitive) and approved for use locally.

It is inherent at edge of grid (where this is usually the problem) to be more costly for everyone when it comes to reliable power supplies.

Another option is to not use an ESS system programming at all, and instead use a backup, or 'ignore AC' system where the grid interactivity is less demanding, and grid code compliance standards are less restrictive.

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dean-d Guy Stewart (Victron Community Manager) ♦♦ commented · Aug 17, 2020 at 06:25 PM

Thanks, @Guy Stewart (Victron Community Manager) ill talk to the distributor about the options. Both of our locations are close to the furthest points on the network in our town. I'm sure this has something to do with it.

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