ESS system with Generator on AC input 2 and Quattro 5kva is not stable

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nismoboy34 asked Nov 6, '19

ESS system with Generator on AC input 2 and Quattro 5kva is not stable

Good day all .

I have a victron quattro 5kva setup with a mppt 250/100 and 10kwh of lithium batteries. Ac input 1 has mains electricity. Ac input 2 has generator input. Now with out the ess assistant geneator charges batteries and supplies loads through the inverter with no issues .

When i enable ess assistant the system functions with solar and grid energy as required. However should the user require generator to backup power or charge the battery the inverter will constantly flip on and off between charge and not charging . The relays will stay on for about 2 mins and off . Then on again then off again. To try all options we have disabled ups mode. And enabled weak ac input. This still doesn't make a difference. I can only assume that this has something to do with grid feed in which is set to grid type other with no feed in . Loss of mains on both ac input 1 and 2 is set to type b safe .

Would changing the type b to disabled on the ac input 2 correct this problem with no adverse effects on the 14kva generator input 2 ??

Or should i be looking for another solution .Thank you in advance for your help and assistance.

ESS Generator

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Guy Stewart (Victron Community Manager) answered · Nov 06, 2019 at 10:39 AM

Hello @Nismoboy34,

First thing is that the system will need to be set up as described in the ESS Manual:

ESS in a system with a generator

Configuring ESS in a system which uses a diesel generator as backup - for extended mains failures - can be achieved. Grid code and Loss of Mains configuration will need special attention, see here.

A Quattro must be used with AC input 1 connected to the generator, and AC input 2 connected to the grid. The role of the generator will be to provide power during a long grid failure.

And on the GX device, select 'Generator' as the AC Input type in the Settings → System setup menu. The system will then enable generator charging; ensure that the generator is properly loaded, and will be automatically switched-off as soon as parameters are met.

Some, bigger or better quality generators, will be able to work with LOM Type B. For other less stable generators it will be required to disable LOM entirely. In that case make the installation such that it is still safe: no simple extensions cords, use enclosed wiring cabinets with warnings on the outside and/or an external ENS.

More information here: https://www.victronenergy.com/live/multiplus_faq

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Willem van Schalkwyk commented · Nov 24, 2019 at 08:25 AM

Dear Guy,

I have read, and you advise that generator needs to be connected to AC1 and Grid to AC2. Please help me understand the logic and benefit of this protocol.

Is AC1 not a ‘higher priority’ input than AC2, meaning that if both are active AC1 is connected? If so (I use CCGX to control generator) then if the generator is automatically started due to low battery SoC during grid failure, then if the grid returns during the period while the generator is running, the grid will not be connected to the Quattro and the genny will continue running until stop conditions are met?

I have a problem similar to an issue discussed in another feed, with a generator disconnecting repeatedly when the battery charge increases to 2kW (10kVA Generator). I am trying to understand all options to get to the bottom of the generator problem.

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hennie-mouton Willem van Schalkwyk commented · Dec 05, 2020 at 06:19 AM

I have same issue as nismoboy34 - an ESS system with a Quattro 8000, mains on AC-IN1 and generator on AC-IN2. When mains failed and GEN on, IN2 does not get used - it shows voltage on AC-IN2, but zero current going to either load or used for battery charge. CCGX is set to reflect MAINS on AC1 and GEN on AC2. It just does not work. I thought it was GEN's frequency, and spent money on getting 49-51 Hz control on the GEN, even though LOM is set for wide frequency range (I forget the exact setting).
So, I have the same question as Willem above:
1) Why if AC-IN1 is the dominant one, does the manual suggest that GEN be on AC-IN1?
2) Why does GEN on AC-IN2 not work?

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Daniël Boekel (Victron Energy Staff) ♦♦ hennie-mouton commented · Dec 05, 2020 at 10:33 AM

Hi @Hennie_Mouton

Using AC-IN1 or -2 for generator depends on the kind of system.

It usually makes more sense to use input 1 (because the system can start from input 1 with an empty battery), the same can apply the other way around, if for example on a boat you want shore power to have priority.

Having a DC charging source (MPPT's) can also make a difference, as they can also cold-boot a system with an empty battery.

So usually generator on AC-IN1 makes more sense.

As to why it doesn't connect to your generator, my guess is that you need to disable LOM detection on that input, as you can read in the document already linked:

https://www.victronenergy.com/live/multiplus_faq

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hennie-mouton Daniël Boekel (Victron Energy Staff) ♦♦ commented · Dec 05, 2020 at 03:57 PM

Thanks Daniel

It was my thought as well that the LOM is keeping AC-IN2 from working, which is why I changed to type B and also added an elecronic pump frequency control to my generator, to keep the frequency pretty constant. The V stays at 230 - 242 V, and the F 49.8 - 51.9 Hz when on generator, no matter the generator load, But AC-IN2 does not allow any power through - AC INPUT graph shows 240 V but 0 Amps on AC2, and shoots to normal 18 A as soon as AC1 (mains) is back.

I must keep mains on AC-IN1, as I don't want to run off generator when mains is back.

What else could I try?

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Daniël Boekel (Victron Energy Staff) ♦♦ hennie-mouton commented · Dec 05, 2020 at 06:10 PM

@Hennie_Mouton

You need to disable LOM detection on that input (not use 'type B' but disable)

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Nicholas Herbst Daniël Boekel (Victron Energy Staff) ♦♦ commented · Jul 15, 2021 at 09:17 AM

Hi @Daniël Boekel (Victron Energy Staff)

I am still struggling to understand why Victron recommends connecting the Generator to AC-IN1 and Grid to AC-IN2 when setting up an ESS system.

Is this just because Victron perceives the Generator as being the primary/preferred supply?

We have a number of ESS setups where we have connected the Generator to AC-IN2, and it is because we enable the feature in Generator Start/Stop Control that states "Do not run Generator when AC1 is in use".

You have also made reference to a cold start condition, suggesting that having the Generator on AC1 allows you to start a system with a depleted battery. Would a Generator on AC2 not provide the same capability to cold start a system?

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Daniël Boekel (Victron Energy Staff) ♦♦ Nicholas Herbst commented · Jul 15, 2021 at 09:30 AM

Hi @Nicholas Herbst

Yes indeed: ac input2 doesn't have cold start possibility.

also: when grid fails but not on all phases (or still a bit of voltage present), the system might not switch to generator input on input 2

I've asked if we can make it possible to select 'do not run generator when AC2 is in use'

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Answer 1 · 2019-11-06T07:23:01Z

petajoule answered · Nov 06, 2019 at 07:23 AM

We have such a configuration running, although we have mains on AC IN-2 and the Genset on AC IN-1 (for priority reasons).

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