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aussiedreamland avatar image
aussiedreamland asked

Multiplus II - ESS - Very unstable grid although loads are fairly stable - Too much waste!

Hi there,

pretty new to the whole ESS Victron thing, but I've learnt a lot over the past weeks and I'm an electronic technician which helps a lot...;)

Here's my setup:

1x Multiplus II GX 48/3000/35-32

1x SmartSolar MPPT 250/60 (connected via VE-Bus & hooked to 4 KWP solar)

2x Plyontech US2000C Batteries (4,8 KWH)

2x PV-Inverters each hooked to 1,5 KWP solar and connected to the grid (one on L2, the other on L3) without communication to the MP.

1x Gridmeter EM24 (RS485)

Everything including the ESS (set to 0 W feed-in) has been configured and running for about 6 weeks and working quite well apart from a very unstable grid when there's not enough power coming from the PV-Inverters and the batteries aren't full yet.

The MP reacts to loads but pushes far to much energy into the grid and instead of then leveling out the fairly constant loads, the MP decreases the energy to the point where energy is pulled from the grid although the loads are still present and stable.

This happens all the time as long as there's not enough power coming from the two PV-Inverters and the batteries aren't full yet.

I don't even use the MP's charger since this only makes things worse, I only use the MPPT to charge the batteries and then I send 1500 W to the grid to make sure I always have more energy than I need. This works fine until the sun starts setting and the solar power decreases to the point where my loads are higher than the produced solar energy.

Once that happens the above issue starts all over again until all the energy is coming from the batteries, but even then, the MP is fairly unstable (sometimes up to +- 2 KW even though there's a stable load of around 300 watts).

I have been reading for weeks in the forums but haven't managed to find an answer to my problem and I'm pretty sure it's not normal.

Any information on how to solve this issue or at least what I could try out would be appreciated...;)

Also, if I can post any other data, let me know...

Thanks...

Roland


The uploaded video shows a 1,4 KW load but the MP is really not being able to get it anywhere close to a zero feed-in.





Multiplus-II
mp2.mp4 (2.9 MiB)
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aussiedreamland avatar image aussiedreamland commented ·
No one has these problems???
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lifeingalicia avatar image lifeingalicia commented ·
Bist du sicher L1 L2 L3 sind korrekt in Reihenfolge aufm EM24 angeschlossen¿

Sending 1500W to grid - So Inverter power is limited to 1500W?

Aller Ueberschuss geht erst in Batterie bis max charging current (32A).

And Multi ist auf L1 (sicher?) Multi software gehet von L1 aus...

Inverter auf L2 und L3 (sicher?) L3 zeigt stabile positive Last L2 negativ relativ stabil?

Auf jeden Fall die Verkablung nochmal genau pruefen

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aussiedreamland avatar image aussiedreamland commented ·

The problem has been fixed, but I don't know exactly what the problem was.

I deleted the ESS assistant on the MP2 and re-installed it with the exact same parameters as before....AND NOW IT WORKS!

Instead of the behavior shown in the first video, the system is now stable within +- 100 Watt when the load is about 2-3 KW.

If the load is under 1 KW it's actually around +- 50 Watt

So I'm happy so far...

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3 Answers
Marco Nijholt avatar image
Marco Nijholt answered ·

Do you have the ESS phase setting configured to "total of all phases" or "individual phase"? If you have it set on individual phase, change it to total of all phases. Its possible this hotfixes the issue of not being able to get the grid to 0 setpoint.

If this "hotfixes" the issue, then the underlying issue might be a wrong order of phases. Victron in single phase setup always assumes its on L1. However if it's actually connected to L2 or L3, the measurements from the meter makes the individual phase regulation mode not work.

If this is indeed the case, then the solution would be to either change the phase victron is on. Or change the phase order on the EM24 so the phase victron is on is on the spot of L1 (switch them on both inputs and outputs).

The reason Total of All phases setting hotfixes is that it looks at the total grid power, and tries to get that to 0. This makes it so it does not matter which phase gets the energy to draw it back to 0. However in single phase regulation it tries to pull each phase to 0, and not the total. It can also lead to wrong "calculated" values on AC loads.

If total of all phases does not resolve this issue or is already configured, you can pretty much ignore my whole response.

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aussiedreamland avatar image
aussiedreamland answered ·

Thanks Marco, but I already have the system set to "all phases" and the Multi's input is connected to "L1", so I think I have it connected correctly.

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netrange avatar image netrange commented ·
... Are the other2 PV Inverters are connected before or after the EM24 ?
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marekp avatar image
marekp answered ·

@Aussiedreamland

Maybe you have recently quite popular problem with the external CT jack in MP-II inverter.

Try inserting 3.5mm plug (many times) into the external CT socket to clean its contacts.

Turn the system OFF first.

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aussiedreamland avatar image aussiedreamland commented ·
I don't use the "CT jack", I have an EM24 as a grid meter, that's it.
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marekp avatar image marekp aussiedreamland commented ·

@Aussiedreamland

If you do not use external CT the internal CT is used.

Unfortunately 3.5mm CT socket sometimes is faulty and internal CT is also disconnected on the 3.5mm socket contacts (Moving those contacts by plugin and unplugging helps to clean them).

This fault can cause erratic valuse of current flowing into the MP-II because even if you have external power meter the internal CT is still used.

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aussiedreamland avatar image aussiedreamland marekp commented ·

How do I find the internal socket of the internal CT?

I probably have to open the MP in some way, correct?

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marekp avatar image marekp aussiedreamland commented ·

@Aussiedreamland

screen-shot-2022-08-16-at-101750-am.png

screen-shot-2022-08-16-at-101816-am.png

To clean the contacts in this "Current Sense" socket just plug in and unplug (many times) a 3.5mm headphones plug.

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screen-shot-2022-08-16-at-101750-am.png (141.6 KiB)
screen-shot-2022-08-16-at-101816-am.png (10.7 KiB)