question

gnagflow avatar image

Why don't 3phase ESS systems support phase compensation functionality for heavy unsymmetrical loads like electric vehicle charging?

Dear Guy Steart at Victron Expert Community,

I can show you 15 very unsatisfied customers within this forum who all have the same problem.

They are very disappointed about the fact that their investment in 3 phase system is not able to make phase compensation and so their investment is not satisfying their needs.

Loading electric vehicles will not be supported by Victron. Is this your strategy and can you tell us that you dont want to support solutions with ESS+EV's or is it just an unwanted failure and this important change request did never pop up at your programming experts and product managers?

Please look at the threads that are unanswered:

https://community.victronenergy.com/questions/55480/ess-system-doesnt-react-not-balanced-to-high-ac-lo.html

https://community.victronenergy.com/questions/53345/phase-compensation-is-not-working-in-3-phase-ess-g.html




3 phase
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It is hard to imagine a 3 phase dc charger, NOT posing an equal load across the input phases.

nobody has a dc charger at home. Prices start for a chinese chargers for 20kW from 5tEUR without transport and tax.

most electric vehicles have 1 phase charger, some have two phase charger and some have three phase charger.

3 phase charger do make equal loads in the input phases.

4 Answers
daryl avatar image
daryl answered ·

I have this problem too.


I have 3 x 5kVA Multiplus 2 units, I read all the documentation (multiple times) and did the victron professional training before I purchased the units and still got caught out by this :-(

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at the moment we are Germany/Austria/Sweden who have the problem. Which country are you from?

I'm in Australia, and I have a large single phase air conditioner that uses more than 5kVA

markus avatar image
markus answered ·

Hi, isn’t this also exactly the reason, why your EV charger is not offically allowed in AT to be connected to the grid? Because it represents a too unsymmetrical load?

So this could be the reason too, why your Multis do not compensate big loads? Becouse it is not allowed with AT Grid Code setting.
...just a guess from my side.

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Hi, thank you for your participation.

Yes, it is not allowed to connect unsymmetric loads > 4.6kW. But it is allowed to buy a car that has a single phase charger that can make unsymmetric loads until 7kW.

But two points:

a) my wallbox manages that the unsymmetric load is always below 4.6kW it reduces the charger load when necessary and reads out all data from the energy meter from the venus-gx. So, this is easy and normal.

b) when providing 2.5kW by the Multi and 4.6kW by the grid, i get the 7kW max. of the charger.

c) i always try to explain problems by extrem points this is 7kW on one phase. Most situations are lower. When i turn on my oven and cook it is the same problem. I mostly do not charge with 7kW, i dont need it, most time i use around 4,5kW on a phase, so that my solar energy from the day can go directly to the car.

d) It is not the problem that 7kW unsymmetric load is not allowed --> most cars can charge only 3.6kW or 4.5kW on one phase, so the problem stays the same. Victron does only support such loads in 3 phase systems with 2.4kW (full power of one inverter, which is on the most inefficient operating point of the inverter)

e) In reality in this situation I invested 1000EUR into a transformer 430V->230V to get out of two phases, one to charge the EV --> only to feed my free solarpower (15kW of panels) into the car, but people who invest in green energy want to have solutions that pay of in some years.

d) You can turn it around like you want. The main players like Froniux, SMA, Solaredge, Costal and ALL others do provide symmetrical inverter power and use phase compensation in combination with a battery storage.

Sounds like a badly designed/chosen system for the desired purpose.

Multiplus/Quattro inverters are supposed to use big batteries and also don't have any way to charge/supply power from solar by themselves.

Sounds like you wanted a grid-tie inverter instead.

This is an interesting discussion.
So for my own understanding: If you consume 7kW on Phase 1, it is from a grid perspective 7-2.4=4.6kW of imbalanced load.
So if you would start to backfeed 2.4kW on Phase 2 and 2.4kW on Phase 3 the imbalance of the phases would get even worse?

The imbalance would be by 9.4 kW then?!

marekp avatar image marekp markus ♦♦ ·

This is exactly what I was thinking.

If the 4.6kW taken from the grid is a problem, than 7kW EV charger should be connected directly to the battery.

7-2.4=4.6 :)

:o) thanks Marek. I have corrected my calculation.

good question, honestly i think that the imbalance only counts loads and a feed in is not a load.
feed imbalance is max. 3.6kW
load imbalance is max. 4.6kW

I think: feed + load is not equal the total imbalance regulated by law.

because:

- my net provider allows me to provide balanced feed in, in big amounts, depending on situation of transformer etc. but usually its not a problem to have 15kW-30kW balanced feed in.
In this situation the grid provider doesn't care about the load.

- and on the other side, the net provider allows, "consumers" on one phase upt to 4.6kW.
In this situation the grid provider doesn't care about a symmetric feed in.

So, probably at the end, the 7kW charger is against the law anytime, but I can also charge with 4.6kW with this charger and this is allowed, but not supported by Victron.

I hope your net provider uses the same logic as the rest of us. :)

The key is the meaning of the word "imbalance".

Imbalance can be measured between phases.

If you can have feed imbalance of 3.6kW that means on one phase 3.6kW on the other ZERO.

But if you feed on phase one 3.6kW and draw on the phase two 4.6kW than "imbalance" is 8.2kW.

Do your net provider have the requirements for this situation?

Just called my electrician. In Austria, only the feed in imbalance must be <3,6kW. We dont have a load balancing rule <4,6kW like Germans have. The unsymmetry is only measured for the feed-in.

woliver avatar image woliver markus ♦♦ ·

Hi Markus,

thera are grid rules in germany for feeding-in and for consumtion. It's a little bit confusing, I know, but you have to accept it for a grid-parallel setup.

"... In the case of unbalanced generating plants, the single-phase generation output must not exceed 4.6 kVA (or 4,6 kW with cos phi =1) at the network connection point with the low-voltage network..."


Forof the grid providers a multiplus three phase setup is a unbalanced system because every phase is handled individual. So a multiplus 5000 with 5000 kVA is a no go.

A possible reason could be, but I am not sure, that it is for the case when a high load on one phase suddenly disappears while the other both phases are at zero. There could be a feed-in-peak to the grid over the 4,6 kVA which can cause an unstable behavior.

marekp avatar image
marekp answered ·

If you have 3 phase system build on 3 MP-II 3000 you have 7.2kW total power of this system.

There is no way you can load one phase with 7kW EV 1 phase charger.

No amount of phase balancing will let you do it.

If yo want to charge your EV with 7kW charger, you need to buy 3-phase charger.

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the key word is "phase compensation" not "phase balancing" that means:

at L1 MP2 delivers 2.5kVA to the grid

at L2 MP2 delivers 2.5KVA to the grid

at L3 MP2 delivers 2.5kVA to suppport the 7.5kVA load of the EV charger on L3.

Its not possible to change the charger in the EV to a 3 phase charger.

You can buy a new car for around 45tEUR. Or you buy addional 3x MP2, or you write a little update on the VenusGX so that the system behaves like every other 3phase inverter hybrid system does, like e.g. Solaredge, Fronius, Costal, ... their inverter systems provide on each phase the same power. So, if you need on any phase 3kW, they provide on each phase 1kW, with phase compensation that means:

INVERTER:

1kVA on L1

1kVA on L2

1kVA on L3

Energy Meter:

-1kVA on L1

-1kVA on L2

+2kVA on L3

makes in total 0W from the grid -> that means phase compensation. The grid supplier only looks at the sum of the 3 phases and not at the individual phases.


That is normal "phase compensation". This has many advantages for the consumers:

a) all the inverters are equally loaded --> longer livetime

b) all inverters work more efficient, because all three work with 1kVA and not one inverter has to take the full load of 3kVA

c) the system has more total power 3x3kVA = 9kVA for imbalanced loads is better than only 3kVA

This is a better solution for ESS applications. There is no single advantage of controlling system that Victron applies for 3 phase systems. This is developed for boats, camping, etc. but not for consumers that use it as ESS solution.

Independet of the fact that most EV chargers dont have a 3phase charger, all big power consumers of the house are not balanced through the 3 phases. When you switch on the oven, than it is on a single phase. When switch on the washing machine, it maybe is on the same phase again. There exists no good balanced load in any house. As good as I try, it is always very unbalanced. The mass on houses on one grid transformer makes in average a kind of balanced load, so it is ok for the grid.

Again.

There is no physical way to push more than 2.4kW continuously through MP-II/3000.

This is not Victron fault, it is just basic physics.

There are 3-phase chargers available on the market and you do not need to buy new car to get it.

Phase compensation, you described, has nothing to do with this problem.

https://www.greencharging.co.uk/single-and-3-phase-charging/

https://www.50five.co.uk/blog/1-phase-and-3-phase-ev-chargers-whats-the-difference.html

https://evtun.com/chargers/accelev-3-phase-charger-11kw-22kw.html


Yes, but this is not the problem. I dont care if it delivers 2.4kW or 2kW that is no difference for the big problem.

I would be happy if i could get 1.5kW *3 = 4.5kW to support a charge.

In this case it is no matter if it delivers 2kw, 2.2kW or 2.4kW continously --> this is nothing to charge a car. You need the power of all three inverters and that requires a change in the controlling programm. Just read this thread:

https://community.victronenergy.com/questions/55480/ess-system-doesnt-react-not-balanced-to-high-ac-lo.html

This is not optimal it requires an update:

1615386914999.png


1615386914999.png (26.9 KiB)

Again.

The only way to pull more than 2.4kW from 3 phase system build on 3x MP-II/3000 is to use 3-phase charger.

Why are you keep saying @gnagflow wants to pull more on a phase?
If you have 3 multiplus, you have the ability to push 3x2.4kW in to the grid. That is 7.2kW
If you have one heavy consumer on one phase that will draw 7..2kW, the total of all phases would be zero.

L1 2.4kW from Multiplus + 4.8kW buying from the grid
L2 2.4kW from Multiplus

L3 2.4kW from Multiplus

At grid meter

L1 +4.8kW

L2 -2.4kW

L3 -2.4kW


Sum of all phases: 0W

That is what we are after. "Phase compensation" not balancing

Yeah, I did, after posting this, and was not fast enough to delete my comment.
Good that you now understand what we are after. I hope someone at Victron also understands what we are after

Now I remember post made by one of the Victron "guru" on this community couple months ago and he wrote that ZERO feed is possible but limiting feed to some other value is not yet possible.

Sorry I do not remember the topic.

I am interested in this because I am in the process of setting up my system, and I am afraid that use of ESS by me will not be possible for many reasons.

One of them being that there is no grid code for Poland.

Let's try and find this 'guru'!

Unfortunately, this has nothing to do with our problem. ZERO feed in is only a thing for people who are not allowed to feed back into the grid, but want to install a grid parallel installation.

Well, naming is one thing. We could call is something else. ZERO feed out then :)

I think we know what is wanted regardless of the naming.
I would like to achieve a "ZERO electricity bill". I am allowed to feed in and take from the grid, as long as the total of all phases are ZERO

I welcome you and i am very happy that you understand the problem. Yes we all want ZERO bill --> 3 Multiplus that only symmetrical invert and are controlled the total of all 3 three phases to be ZERO.

I opened this thread for two reasons:

1. getting support from other people, who have the same problem (you)

2. i hoped that any victron staff will answer properly, why they dont want to invest a day in a change request that helps soo many people, who are disappointed of the way the 3 phase system works out.

My result from this thread is very disappointing:

1. most people who answer dont understand the problem

2. Victron does not comment.

--> maybe the world is different to Austria/Germany and our market is somehow not of interest (i am joking)

--> maybe Victron does also not understand, how ZERO electricity bill is helping at ESS customer setups.


But maybe we have to sign a petitition: :-(

For sure, you get my sign! ;-)

We are three people here in Sweden that just made a 3-phase victron battery solution, that would gladly join in

ZERO feed is just version of "Power_limit_feed".

ZERO is possible but any other number of kW feed or load is not possible in current soft.

Is it not what you are after?

No it is definitely not.
With three inverters we have 7.2kW of power at our disposal.
If the house needs 4kW, take 4kW of the 7.2kW, distribute it how every you want, as long as it is 4kW.

If the house needs 16kW of power... take 7.2kW from the inverters and buy the rest from the grid.

It is not an absolute ZERO. We are still allowed to buy electricity, it is just that we don't want too, if the inverters could give it to us.

A better name for "ZERO electricity bills" is
"Even phase distribution"

Simplified calculation:

Grid total needed 5000W
Number of phases 3

5000 / 3 = 1666 W

Each victron should invert 1666 W of power and send to each phase.

(the more advanced calculation - some aspect to grid maximum allowed power needs to be taken in to consideration).

Eg you need 12000W. You have a PV array that gives you 9000W. (3000W per phase)
You need to buy 3000W. If the load is uneven. Say you charge two cars. On each phase with 6000W each

L1 +3000 (6kW car and 3000W from PV)
L2 +3000 (6kW car and 3000W from PV)
L3 -3000 (just 3kW from PV)

Victron would need to offset 3000W. (1000W/phase) that would be

L1 +2000 (6kW car and 3kW from PV and 1kW from multiplus)
L2 +2000 (6kW car and 3kW from PV and 1kW from multiplus)
L3 -4000 (3kW from PV and 1kW from multiplus)

Total is now ZERO

But special consideration needs to be taken for L3 it would exceed the feed out capability of a 16A grid fuse.

The result would have to be

L1 +1800 (6kW car and 3kW from PV and 1.2kW from multiplus)
L2 +1800 (6kW car and 3kW from PV and 1.2kW from multiplus)
L3 -3600 (3kW from PV and 0.6kW from multiplus)

(but then is wouldn't bee even distribution, so with even distribution it would be)

L1 +2200 (6kW car and 3kW from PV and 0.8kW from multiplus)
L2 +2200 (6kW car and 3kW from PV and 0.8kW from multiplus)
L3 -3800 (3kW from PV and 0.8kW from multiplus)

You are buying 600W


I am getting confused here.

Is it not you who complained (in the other topic) that you have max grid point set to 500W and your Victron is taking from grid 990W?

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David Ferguson avatar image
David Ferguson answered ·

Why not run all your inverters on one phase (parallel) and use phase compensation rather than run in pure three phase mode?

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In some countries, you are not permitted to connect too much load to a single-phase (Unbalanced loading).
For example in Germany the limit is 4,6kVA

yes in Austria it is the same. But L1 -2,5kVA, L2 -2,5kVA, L3 +2,5kVA is already 7,5kVA which you can provide. And on the load, in my specific case, of a hyundai kona with one phase 7kW charger -2,5kva provided on the charger phase by the inverter results in a <4,5kva load unbalancing.

With openWB it is easy to set a limit for unbalancing load and it regulates the charge current automatically. So, it is no problem to set everthing within all regulations.

But on the other side, in reality most customers don't care about their unbalancing EV loads. They just use an 32A fuse and a cable an thats it - use one phase for the car and the other two for the house.

Most people i know who buy a car, also have solar. Almost all who invest in a car and in solar play with the thought of a storage.


Then do it off-grid.

I had one 5kva MP2 inverter which was not going to get approved by the grid supplier, because it is not allowed to have a single phase inverter >3,6kva. Than i changed the whole system to 3x3kva MP2 to get approval.

It‘s exactly the same in my case. The german net provider doesn‘t accept one multiplus 5000 so I switched to three multiplus2 3000 in a three phase setup. The main problem is that if I have a load higher then 2400 W on one Phase I have grid consumption and the other two multiplus are in standby.

In Germany we have on the other hand a net metering which counts the power-sum over all phases. So why is it not possible that a multiplus on phase 1 which is on his power limit will be supported by the other multiplus’s on phase 2 and 3?! That‘s at the moment a real problem not only for german customers.

exactly. Many people have the same problem. But Victron does not answer to the question since a year.

And I realy realy like all the Victron products - but i dont understand, why this problem doesnt find an ear.

There is no physical way to move power between phases.

For higher loads you need 3-phase supply.

yes of course. But in countries like Germany and Austria and i dont know how the rest in europe works, the grid supplier only measures the "net" consumption over the phases.

Imagine:

- you have a one phase inverter MP2 3kVA on phase L1 which delivers 1kVA.

- on the other side you cook and it consumes 1kVA on L2

the grid meter does count the total of all three phases that is in this case ZERO. You have to pay ZERO EURO to the grid supplier and energy supplier. You served your energy requirement from your powerwall.

This is so-called "phase compensation" or "net-metering" or I dont what the right name else could be.

You dont shift energy between phases,


Measuring and transporting energy through phases are two different things.

If I understood you correctly, you want to load one phase with 7kW EV 1 phase charger but that phase is only capable of providing 2.4 kW.

It will not work.

It has nothing to do with phase_compensation or net_metering.

Almost right. The phase can provide around 35A*230V from the grid plus 2.4kW from the MP2 inverter.

And it is working when you put all three inverters on phase L1 and you put the car with 7kW charger on phase L2, than I can load my car for free, if my 60kWH powerwall is filled up with the sun power.

yes it works. i did it and it works.

Victron calls it within their settings "phase compensation" and it is only possible to use it, when you dont have a three phase system. I have serveral such systems installed. It works quite well.


OK.

If your grid can provide max 5kW per phase and you have 3F MP-II/3000 system, you can use power assist to add 2kW from batteries to 5kW from grid and this way you get 7kW for EV charger on one phase.

For it to work you need proper size battery and/or enough PV power either AC or DC.

I am not sure if the battery will be charged at the same time from other 2 grid phases.

What we in Germany need is a compansation over all phases so that the sum for the grid meter in an on-grid system is zero.

A parallel installation of two multiplus per phase isn‘t allowed by the grid provider. But in sum 7200w ober all phases ( each phase 2400W) to compansate a high load on one phase is allowed.

It has nothing to do with physics, is only math ;-)

Thank you that help and understand me.


Are you saying that current flow differently in Germany then in the rest of the world?

If you can only draw 3kW per phase, there is no physical possibility to draw 9kW from one phase.

Perhaps You missunderstood the situation.

The victron system setup is a three phase ESS system with three multiplus2 3000 installed as on-grid system only connected to the grid on AC IN each phase.

So if your load on phase 1 exceeds 2400 W the rest can‘t be compensated so it will come from the grid and you pay for it.

If the ESS system would behave symmetrical like other hybrid invertes do ( eg fronius or e3dc) the load will be compensated with the invertes on the other phases.

For example:

L1 has a load with 3000W each multiplus should deliver 1000W so that the sum for the grid meter is zero.

At the moment ESS behaves that on L1 only 2400 W will be delivered and 600 W will be delivered from the grid. The Meter of the grid provider only counts the sum of all phases. So you could draw on one phase from the grid and deliver on the other phases to the grid, if the sum is zero everything is fine.

In Germany unsymmetrical inverters like Victron ESS are only allowed to feed max 4,6 KW per phase into the grid. If you want to deliver more than 4,6 KW to the grid the power output of the inverter per phase must be symmetrical. E.g. L1= +5000W , L2= +5000W, L3= +5000W.


If you would habe such a Victron behaviour you could deliver symmetrical 3x 2400W to the grid to compensate a Load on one Phase with 7200 W and the grid meter would display zero!

OK, so your problem is not the inability to draw 7kW from one phase, but fact that when you do, 2.4kW comes from batteries and 4.6kW from the grid and you have to pay for this 4.6kW. You would not have to pay for it, if the other two phases had fed 4.6kW to the grid, so the total energy is ZERO.

If that is correct, why its so important to you, not to draw power from the grid?

That energy in the batteries would have to come from somewhere.

Battery storage efficiency is lower than 100%.

Yes, now we come closer ;-)

The energy in the Battery comes from solar for free, so each multiplus delivers max 2,4KW and in sum 7,2 KW to compensate loads which are in sum 7,2 KW but distributed unbalanced over all phases.

In Germany we have to pay only for the total sum of energy consumed over all phases, it doesn‘t matter if I sell on one phase and buy on the other phase.

But if the multiplus only compansate unbalanced loads in each phase separatly I have to pay for the 4,6 KW to my grid provider while the other two multiplus do nothing.


What we need is mentioned in the Victron ESS manual but not possible to choose in the software setup.

Otherwise the multiplus hasn‘t to work on its limit to compansate a load of 2,4 KW on phase 1 because each multi could deliver 800 W from the battery at night.

2c2d6ea3-ef6f-4bce-a405-fb1545b4fdd8.jpeg

Now I got it.

The reason why it was hard for me to get your point, is that in Poland we do not have the "net_metering" and only one out of four energy providers uses proper vector based phase_balancing. :(

We can store our PV energy in the grid system in the summer to take it out in the winter with 20% loss (or 30% if PV is bigger than 10kWp).

Battery is for that reason not very popular.

The one reason to have the battery is to auto-consume more energy on the spot and in the grid storing only that part of it that is needed for winter.

The other reason for battery and Victron is to compensate for terrible grid quality and blackouts.


Oh! That's cool! So there's no need for big battery systems in Poland.

In Germany we pay arround 0,30€ per KWh from the Grid and you get only arround 0,08€ per KWh delivered to the grid. So your main concearn is to use as much solar energy directly whitout the grid provider. In case of that, battery (hybrid) systems become more and more popular in Germany.

In my example above I had to pay 0,30€ x 4,6 KWh = 1,38 €/h extra while two multis do nothing and the battery is fully charged. On the other hand one big multiplus2 5000 isn't allowed by the grid provider in germany. So the only possibility is the multiplus2 3000 as single or three phase setup. But in an three phase setup with high unbalanced loads over 2,4KW you have no advantage with ESS.


I think if Victron doesn't realize this problem of the missing possibility to setup a symmetrical ESS profile in the GX-Device, the German market will flew by victron. The german grid is so stable that most of the customers would use an ESS setup with grid connection on AC IN with an EM24 or ET340 and also the loads connected on the input side. (this is also the favored setup of other big players like Fronius or SMA in Germany). There is no need to connect all the loads through the multi on AC OUT1 or AC OUT2.

Yes, it is cool but it has its drawbacks.

One is that you can store your energy in the grid only for one year.

If you put into the grid more than you can use in the year it will be lost.

We have no possibility of getting payed for that unused in the year EE.

Going back to your problem of charging EV.

Why not charging it directly from the battery.

You can have your EV charger connected to the battery through one powerful inverter. If you have 7kW EV charger you can put 2 MP-II/5000 in parallel.

The best would be the EV charger that can be connected directly to the 48V battery.


In my case I would use the setup also for my house which is an three phase AC System. For that only one multi 3000 is allowed by the grid provider in an on-grid setup.


If a multi 5000 would be allowed I had no need for an three phase system because most of my loads are in sum over all phases not higher than 4000W but some loads on a single phase are higher than 3000W

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But the OP wants to charge an electric vehicle, not to feed in into the grid.

Yes, on one phase with 7KW as I understood.


Wish:

L1: -7KW EV as load (+2,33KW by Multi)

L2: +2,33KW by Multi

L3: +2,33KW by Multi

--> total sum ZERO!


Reality:

L1: -7KW EV as load (+2,4KW by Multi)

L2: 0KW by Multi

L3: 0KW by Multi

--> total sum -4,6KW from the grid !!!

its not allowed, the grid supplier only approves to put unbalanced inverters on one phase <3.6kVA

Because that would provide more power than the main fuses would tolerate.
I have 3x20A fuses. I can only buy or sell a total of 4800W on each phase (and actually only 3800 W on the cable connected to the victron. It is on a 16A fuse)

When my PV inverter SolarEdge produces 9000W from the sun, it distributes it evenly on all phases. 3000W on each.

I can have major imbalances between the phases, if I charge my car it draw 25A from L1, but L2 and L3 can still be selling (l1 is selling some, but mostly buying)


If Victron could have an "ESS Assistant option" like "Even phase distribution" yes/no

It would solve everyones problem, and everybody would be happy with their victron 3-phase setup