Multiplus not limiting inductive load effect on Induction Generator - Shore Power Curret Limit

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undergrowth asked May 19, '23

Multiplus not limiting inductive load effect on Induction Generator - Shore Power Curret Limit

I am Dyslexic and have tried to gather info to explain our problem bellow, and been as clear as i can.

  TLDR: Shore power limit on a Multiplus does not appear to activate quickly enough to stop inductive load problems with our induction generator and controller. (IGC)

  Overview: We are struggling with the detail of what happens when Shore Power Limit, is limiting. (does it have a curve? is it timed? what bandwidth activates it? how does Power Factor effect its activation?) This matters to us because the Shore Power Limit is needed to protect our Hydro induction generator and controller from inductive loads.

  Scenario calculations: We live in an off-grid housing coop with Solar and Hydro. We are using the power assist feature on our Multi-plus compact 24v 2000 50-30 230V Which has a Shore power limit of 4.5amps. Latest Firmware. A colour GX screen. Our hydro generator is an induction motor with an Induction Load Controller (IGC). The IGC needs half of the power produced by the hydro as 'headroom' to balance inductive loads.

Edit: (added info)

The IGC dumps the spare hydro power variably to our immersion hot-water tank / heating element before the Victron AC input.  
We have two 12 volt Rolls S12 290Ah AGM batteries (24v)
We have a 250/85 MC4 Maximum Power Point Tracker (MPPT)
We have 2k of solar (angled for summer sun when our hydro is off)
And the Multi-plus compact 24v 2000 50-30 230V

 The lowest 4.5 amp shore-power low current limit setting on our Victron is 1035W at 230V
 The IGC needs double this to balance the generator 2070W at 230v (9Amps) 
Our hydro produces 2400W @ 230v (10.4Amps) Max stably.

Problem: When a washing machine (10Amp Max) is powered with element and motor engaged (8-9Amps on a clamp meter) the IGC frequency and voltage are not balanced enough and the washing machine 'blanks off' at cycle points and restarts the portion of the cycle. Other induction loads like fridges and battery chargers are Audibly strained.
The Multiplus switches to Inverting, but not in time to limit the Induction generator effecting the voltage and frequency. With the batteries and solar providing most of the power the induction loads still effect the Induction generator enough for the frequency and voltage to effect the washing machine again. It switches back and forth syncing the waveforms. 

Other factors: I did try narrowing the low and high voltage and frequency range via victron connect 3 and our Colour GX. I did also think about a 'prorotise solar' Ve configure assistant, to protect the AC input a lot of the time, but the same problem would exist when a higher loads are present.
Our washing machine benefits from the Victrons ability to provide more than 2K to the house because it can supplement the 2k from hydro so we are capable of 3K for shorter periods or sunny times.

N.B The IGC dumps the spare hydro power variably to our immersion hot-water tank / heating element before the Victron AC input.  

The Question we need help on: can anyone think of a way to find out what is going on at the point the limit kicks in? i.e whether the inductive loads power factors are effecting the Victrons ability to limit? Or where details/settings of this might be online? If I can get this Charger inverter to limit, then i could justify advising the Housing Coop to replace it for a model with an even lower shore power setting. (see bellow) wich would work when our hydro is running lower than 2.4K (when the induction problems are much worse)

Possible solution 1. Buy a different Victron Charger/Invertor with a lower shore power Limit.

MultiPlus 24/2000/50-32 - 2.4 Amps
MultiPlus-II 24/3000/70-32 - 3.6 Amps
MultiPlus Compact 24/2000/50-30 - 4.4 Amps (Our installed invertor chrager)

  Possible solution 2. Buy 2x vicron 16a 24v Bluesmart battery chargers with a Victron Digital Control Display to limit charge current to four 'stages'. Or a larger Skyler 25A charger with variable charge control. But with higher losses and inverter working all the time.

Thanks for reading. Phew that took 6 hours writing!

Multiplus-II MultiPlus Quattro Inverter Charger current limit shorepower

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Michelle Konzack commented · May 20, 2023 at 05:20 AM

I would say, your MultiPlus is one number to small. A bigger 3000VA would eat it.

The MultiPlus 2kVA has only 1600W which is simply to small to catch the starting load of the Freezer/Fridge/Washing machine.

I strongly suggest the MultiPlus 24/3000 since you are Off-the-Grid and do not need the features of the MultiPlus-II and also save you some bucks.

P.S.: An Induction Load Controller which suck 50% of the produced energy is highly inefficient. What are you doing with 1000W heat energy and maybe even more? Heating your house?

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undergrowth Michelle Konzack commented · May 24, 2023 at 11:40 AM

Thnak you, yes i agree, a larger MultiPlus would help, though our batteries are only 2x Rolls 290Ah 12v Thanks for the info and recomendations.

And yes, though the hydro is quite often lower than 2.4k (average 800w for most of the year) we use the spare power to hear our twin coil immersioin heater, and once thats full, the load controler switches to a 40 year old, proberably experimental underfloor heating - which it never touches the sides of, but is a good dump. :o)

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Modifications Space

Node Red Space

Answer 1 · 2023-05-20T03:15:14Z

mvas answered · May 20, 2023 at 03:15 AM

Have you tried the "Weak AC" setting?

Is "Dynamic Current Limiter" enabled?

Voltage Drop on generator wires?

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undergrowth commented · May 24, 2023 at 04:35 PM

Thank you, I have tried 'Weak AC' setting after your suggestion, and previously the 'Dynamic current' setting. To no avail that i can see.

The hydro generator wires are propperly sized we think (50M on 3X6 XLPE 1KV BS5467) the Induction Generator Controler (IGC) is at the house end of the 50M

I have now realised a marked difference on inductive loads between the 2 (or 4) modes of the Multplus. I might have got the ANmes of the Modes wrong.

✔ While Inverting, using batteries and solar (with 4.5a of hydro assisting) the inductive loads don't apear to effect the hydro or IGC or washing machine - i.e the victron does not cut the AC input, the washing machine does not 'blank' off (presumably low/high voltage or high/low frequncy) and the IGC does not go into overvoltage or cut the Hydro. The Multiplus is happy with a 2.4kw of load - washing machine element and motor plus fridge motor and other house loads.
✖ While in Assist mode (with battery and solar assisting the 4.5 amps of hydro) the washing machine is not ok.

This can be proved again, when the washing machine is using lots of power and the Victron is in inverting mode, everything is fine. But when the heating element portion of its cycle has ended, the Multipluss switches to Assist Mode (because load is reduced from 1.6kw to 400w) the washing machine then 'blanks off'. BUT if i then put a load of a 1kw heater on in the house, the washing machiene is fine, as the victron is Inverting mode again.

I presumbe the 4.5amp shore limit and the load are the deciding factors of which mode to be in?

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Michelle Konzack undergrowth commented · May 25, 2023 at 07:03 AM

How do you run a load of 2,4kW on a Multiplus Compact 24/2000?

Since your Hydro Power Plant does not deliver a constant power, the Inverter is hopeless too small. It will be forced to run always under full load.

For your installation you need minimal a 3000VA version.

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undergrowth Michelle Konzack commented · May 26, 2023 at 12:23 PM

Thanks for the further replies Michelle. We apriciate the help and the conversation.

Question: How do you run a load of 2,4kW on a Multiplus Compact 24/2000?

As i understand it, the multipluss can only invert 2kva, but it's output stage can handle more. In assist mode as the two AC sources wavforms are in sync, it can also combine them to handle larger loads. It gives a warning light at some point, but between 2-2.6kw it is fine. I saw 3kw flash past once.

Back to the original question:

We want to know why the input current limit is not limiting inductive loads. A new Multipluss might not help if we have the same problem. The current Multipluss runs the washing machine ok in 'inverting assist mode'. But not in 'passthrough assist mode'. A larger multipluss will help with our washing machine when only using batteries and solar, but only if we had more batteries. They are very small. ATM it doesn't cope with out assist. It's low battery, not over-current that stops it. But i agree a 3k invertor would be more comfortable. It's a trade off with how low the shore power limit goes through atm. (This one was sized for solar only. The original idea was to run on solar in summer and hydro in winter, but we ended up with an invertor that can sync AC sources. So we want the assist modes to work)

We are lookimg at a 3k invertor as an option, as stated in the original post, however before de-installing and selling and buying, our main question surrounds why the multiplus is not limiting inductive loads via the shore power setting (when conditions on paper should allow it to). 4.5 amps setting - 2.4kw production on hydro - double the 4.5amp setting so that the Induction generator controler can have 50% headroom for inductive loads. And atm this does works when the Victron is inverting primarily with assist.

It seems to me there are effectivley 4 modes:

1. Passthough (AC generator only)

2. Passthrough + Assisst (as above but with Invertor power synced and added from DC batteries and solar)

3. Inverting (DC batteries and solar only)

4. Inverting + Assist (as above buit with Generator power synced and added from hydro)

Inductive loads are a problem in 1. and 2. and don't apear to be a problem in 3 and 4.

The system gets rapidly even more untenable when the hydro is turned down atm and only producing 600w as the victron Input Current Limit setting can't get anywhere near that low.

We are trying not to invert most of the time. (more efficinent and saves our equipment) Opperating the multipluss in passthrough mode. If the load rises above the capacity of the Hydro generator (wich varies 600w to 2.4k.) the multipluss will assist with battery. Any spare power going to our hot water tank before the Victron.

We are trying to find out if we should sadly get two battery chargers instead of a ne victron, and send the hydro into the batteries instead with a switch to limit their charge rate based in how high our hydro is running.

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Answer 2 · 2023-05-27T03:56:15Z

Michelle Konzack answered · May 27, 2023 at 03:56 AM

@undergrowth

Goid morning,

I have just used a small 750W GenSet on my MultiPlus-II 24/5000/120-50 and configured it for 1 and 2 in your list...

My 5000VA MultiPlus-II got a hickup when I started my convection Bakingoven (Camry CR-6008) with 2000W. Both mode did not work at all, because the minimum input is for my Inverter 6A while the GenSet deliver only around 3A.

Ok, then I used my 2000VA GenSet and also here my MultiPlus-II got a hickup. The typelable on the GenSet show maximum current, but I limited it to 6A, because this cheap 300€ GenSet simply does not proved the 2kW.

However, it worked when I rented several month ago a SDMO/Kohle HX6000 which can deliver up to 4800W but I limited the input current to 15A. The MultiPlus-II was charging with 3800W and when I switched a load of ~6000W on, the Baking oven, two induction plates plus standard loads like fridge and freezer and heating circulation pumps, it was working.

Hence my conclusion is, if the ACin can support the same load an the AC1out (4kW) then everything is working fine, but if the I put source has lesser power as the output of the Inverter, then it hit some problems.

Even with viewing all the training videos and reading the manuals, I was not able, to get the setup (6kW output) working with a smaller GenSet as the HX6000.

Maybe someone can enlighten me too.

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