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gagan-ranatunga avatar image
gagan-ranatunga asked

Quattro 15kw AC coupled with fronius and AC input generator

HI I have a system with a Quattro 15kva and fronius gen plus 5.0 and a generator as the AC input I have used PV assistant and generator start stop and a general flag to ignore ac input.

The issue I am having is when the generator is on during the daytime and if the quattro output is low assume 700Ws, the Fronius trips out and I checked the frequency and it fluctuates from 48.8 to 53Hz which causes the Fronius to trip.

It only happens when the load is low.

The battery was at 48% with 6xUS3000c batteries.

1717836232211.png

This shows the generator inputting 2kws

1717836287604.png

At 11.45am the fronius drops to 0 with High Frequency fault


1717836472186.png


The frequency Jumps upto 53.1hz which affects the fronius to trip. Ignore the frequency fluctuations before 9.30am, it was because of the pv assistant configured wrong.

MultiPlus Quattro Inverter ChargerAC PV CouplingFroniusac ignore
1717836232211.png (27.4 KiB)
1717836287604.png (54.8 KiB)
1717836472186.png (155.1 KiB)
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7 Answers
gagan-ranatunga avatar image
gagan-ranatunga answered ·
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Matthias Lange - DE avatar image Matthias Lange - DE ♦ commented ·

"crying" for attention isn't appreciated and I tend to ignore such questions ... for a while.

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gagan-ranatunga avatar image gagan-ranatunga Matthias Lange - DE ♦ commented ·
  1. @Matthias Lange - DE sorry for troubling you. Apologies !
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sean avatar image
sean answered ·

Do a little research in the ESS documentation, specifically the 1:1 rule - all should be revealed.

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gagan-ranatunga avatar image gagan-ranatunga commented ·
HI Sean,

I read it and I have used a PV assistant, not the ESS assistant but I still cant figure out whats wrong with the frequencies jumping up to 53Hz when there is a lower load.

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vicens avatar image
vicens answered ·

Esto pasa porque el fronius injecta energia hacia el generador.

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Alexandra avatar image
Alexandra answered ·

@Gagan Ranatunga

The fluctuations is likely generator instability. Try lowering the input current limit to stabilise it. Unless it is one that does not have great regulation? Just guesses here. But to do with that.

Second thing is add DC mppts lower loads are easier to run off that. Also battery absorption charge is easier for the system to take care of.

And check the Fronius frequency needs inthe ESS manual. Yes PV assistant is not ESS but fronius needs what it needs.

The control and settings for fronius as well need to be correct as well.

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gagan-ranatunga avatar image gagan-ranatunga commented ·
HI @Alexandra thanks alot for the reply, My only issue is when the load drops to close to 500ws the whole system frequency ramps up to 53Hz, I have no Idea why this is happening generator is around 3kw and the solar at that time is close to 2kws. I have used a PV assistant not the ESS.
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Alexandra avatar image Alexandra ♦ gagan-ranatunga commented ·

The pv assistant doesn't work when there is incoming grid power. That is why it is designed and used for offgrid.

The frequency shift settings are the same as ESS.

What frequency is the generator output?

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gagan-ranatunga avatar image gagan-ranatunga Alexandra ♦ commented ·

HI @Alexandra the generator output is 50.1Hz and do u mean that i need to use ESS assistant and not the PV assistant? but if I put the ESS assistant it will try to feedback to the Ac input isnt it?

I have attached the AC output and AC input frequencies

AC output



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1717920486699.png (195.3 KiB)
Alexandra avatar image Alexandra ♦ gagan-ranatunga commented ·

The pv assistant is designed for offgrid. If you are offgrid use it. What i am saying though is that the PV assistant switches off pv production when grid or generator are present on the input.

ESS mixes the two.

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gagan-ranatunga avatar image gagan-ranatunga Alexandra ♦ commented ·
Hi yes i want to mix both so both can supply and charge but issue is what should i use as grid standard and will it start injecting power back to the generator
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gagan-ranatunga avatar image gagan-ranatunga gagan-ranatunga commented ·
@Alexandra
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Alexandra avatar image Alexandra ♦ gagan-ranatunga commented ·

You will have to use ESS.

Then set the generator to run a frequency that throttles the fronius a bit to prevent feedback.

Use grid code other for ESS since you don't technically have a grid.

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gagan-ranatunga avatar image gagan-ranatunga Alexandra ♦ commented ·
HI @Alexandra I am using another solar system with batteries as the AC input on the Quattro, technically it is another offgrid system connected as the AC input to the quattro.

So you are suggesting me to put the ESS assistant and use grid standard as other isnt it?

I still have to ignore the AC input until the SOC drops to 50% and after 80% charged. Can I use the General flag and Gen start stop assistants with the ESS?

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gagan-ranatunga avatar image gagan-ranatunga gagan-ranatunga commented ·
@Alexandra and Do i need to use the ZERO feed in on fronius aswell?
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Alexandra avatar image Alexandra ♦ gagan-ranatunga commented ·

@Gagan Ranatunga

Yes. And have a higher grid set point as well.

Your system is starting too sound too complicated for the forum.

It is probably much better to seek advice from and experienced installer or distributor.

Please remember we dont have details of your system. Advice found here will be very general since i am not privvy to all the information about your system. And unless you know how to evaluate what you are discussing it can cause damage.

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gagan-ranatunga avatar image
gagan-ranatunga answered ·

Hi @Alexandra, thank you heaps on your help, I will test this and see whether it works.

So is it okay if i use the generator start stop and general flag with the ess?

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gagan-ranatunga avatar image
gagan-ranatunga answered ·

Hi @Alexandra

The system seems to be working but it sends close to 100ws back to the generator input, any idea on how to fix this?

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Alexandra avatar image Alexandra ♦ commented ·
@Gagan Ranatunga

Run the generator at a higher frequency.

Or set a higher grid set point. This you wil have to experiment with.

Make sure ac coupled feedback is switched off.

Change also the LOM detection.

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gagan-ranatunga avatar image
gagan-ranatunga answered ·

hi @Alexandra do u mean to disable the Lom detection or?

And on the fronius do I need to change the settings for zero feed in using modbus

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Alexandra avatar image Alexandra ♦ commented ·
No in ess settings switch off the feedback there.

Make sure the fronius is programmed as described in the ess manual. Please take time to read it

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gagan-ranatunga avatar image gagan-ranatunga Alexandra ♦ commented ·
Hi @Alexandra sorry for bothering you, I still have the issue of backfeeding to generator, I dont have a datamanager on the genplus 24 fronius inverter, so is it fine if I only untick the grid feed in on the ess menu?


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Alexandra avatar image Alexandra ♦ gagan-ranatunga commented ·
@Gagan Ranatunga


How is it connected to the GX then? ESS cannot control what it does not know exists.


The only other way is to throttle using generator output frequency as previously mentioned.

But if you are feeding back then is suggests you have enough production to cover load so why is the generator running?

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gagan-ranatunga avatar image gagan-ranatunga Alexandra ♦ commented ·
Hi @Alexandra i need to run the generator when the soc drops to 50% and stops at 80% this usually happens during the night time but in rare cases like winter time during the daytime the soc can go below 50% thats when both should work together.

My issue is what happens if the generator is on and then the sun comes out and the fronius puts out the max power.

With the pv assistant I had this issue when the generator starts and when the sun comes out the fronius trips with high freq error, that I understood with what you said about pv assistant where freq shift will stop when the ac input is active.


Im running gen start stop and general flag to ignore the ac input.

Coz on my fronius web i cant see any setting to change the modbus settings

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