question

wesley-corbet avatar image
wesley-corbet asked

3 Phase Quattro, ESS and 3 phase Gen Set on AC In 2

Hi Matthijs,

I have passed the question below on to my distributor on around Oct 26 and whilst they are attempting to assist me, I do not have a solution yet and feel I need some higher level advice on this occasion. The system is installed, it is an on-grid system, is there a way to make this work? Despite the gen set being brand new and 33KVA, it is obviously not supplying 'mains quality' power and unless I disable AS4777, the gen input will not be accepted by the Quattro's. I need to keep the AS4777 settings, can you recommend a solution?

I designed the system using the Quattro's with 2 AC inputs purposely so grid and generator could be utilised as per the Quattro data sheet and did not expect this issue. It seems to me that the selected grid code settings are applied to both AC inputs and unless they can be separated, it cannot work.

The system is in the 30-100KW category as the 15KW's of PV inverters downstream are added to the overall capacity, so I also have secondary grid protection installed by way of an external AS4777 approved protection relay (in case you were wondering about on-grid compliance).

Thanks,

Wes Corbet


Previous question:

I have recently installed a 3 Phase on-grid ESS system using 3 x Quattro 10's with back-up 33KVA 3 phase diesel Gen set. The issue I am having is the system does not accept any current from the gen set despite the gen voltage being present on the AC input 2 terminals of the Quattro's, AC In 2 being programmed for Generator in the GX (AC Input 1 is grid) and having the grid voltage, AC In 1 turned off.

I switched the 3 Quattro's to charger only with gen on and grid off, no luck there.

I tried most things suggested previously on the community also with no luck.

Whilst onsite, I did change the grid code from AS4777 to "Other Not compliant to any grid code standard", I suspected the strict grid settings for AC Input 1 (grid) might also be active for AC Input 2 (gen set) and the charging started, at least for a couple of minutes before it disconnected (grid still disconnected)

I checked the NS protection Log after it stopped charging and there was an error there referencing "ROCOF". I then took particular notice of the gen-sets frequency and it seemed to change quite quickly from 49.8Hz up to 50.4Hz.

Question, do AC input 1 and AC input 2 share the same grid settings when a country code is selected? To get my system to work correctly it would seem I need the grid compliant settings for AC Input 1 and more relaxed settings (or user configurable settings), especially frequency, for the generator on AC input 2.

@mvader (Victron Energy)

ESSGenerator
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

5 Answers
Paul B avatar image
Paul B answered ·

I MAYBE big time wrong here - so please double check this first - but my thoughts are the complying with a grid code is only needed when you are connected to the grid.

If you are using a generator then you are OFF grid then the code does not apply so diable the lom associated with the generators connection

so disable the LOM setting for the AC2 in and then the gen should work fine

thats if ACin2 is the generator or vise /versa


do the same on ALL 3 inverters if you do do this


1636291045171.png


1636291045171.png (20.9 KiB)
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

wesley-corbet avatar image
wesley-corbet answered ·

Thanks for taking your time to reply Paul.

The problem is the system is grid connected with a generator. If the grid has failed and the batteries are flat, it will automatically start the generator on low SOC. You are correct that when running on generator without the grid, the grid code settings don't apply, however, as it is always a grid connected system, the country code settings are required. Disabling of the grid code settings would need to happen automatically when the system becomes an off-grid system, unfortunately there is nothing I can do in the software to enable this. An idea I had was once the AC input was assigned to a generator in the GX, the grid code settings are disabled for that input, or alternatively, a check box the same as for LOM, so the grid code can be enabled or disabled for each AC input. Obviously this would require some code and some time to make this happen and there may also be wider implications. I just need some advice from Victron, I am hoping they may have a solution without needing any re-design.

1 comment
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Paul B avatar image Paul B commented ·
Hi Wesely, but why are you wanting to change the country code, that can stay as it is.

the generator and the grid are never connected at the same time so you are on grid when connected to AC1 Grid power and then OFFGRID when connected to the generator - or am I missing something

the lom is only being turned off for the generator on AC2 and then the generator then connects - is this not the case, then when the Gernerators stops and the grid comes back online then the lom is operational again for the grid on AC1
0 Likes 0 ·
wesley-corbet avatar image
wesley-corbet answered ·

Hi Paul,

Thanks again for your help.

This might help to explain further.

Like this with gen in AC IN 2, it does not accept the gen set:

1636330671856.png

Like this, it does accept the gen set:

1636330891883.png

The voltage is quite stable from the gen set, the frequency is a bit up and down as previously mentioned. I believe the issue is frequency related, either rate of change of frequency or frequency imbalance between phases. Disabling LOM does not disable all of the grid protection settings and there is a frequency setting left in there causing the issue.

Thanks Wes Corbet


1636330671856.png (25.4 KiB)
1636330891883.png (20.8 KiB)
1 comment
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

porcini avatar image porcini commented ·
Hello, your screenshot shows UPS function enabled, have you already disabled that?
0 Likes 0 ·
wesley-corbet avatar image
wesley-corbet answered ·

Hi,

Despite no attempt from Victron to assist with this issue, I have, through my own investigating, discovered that with the country code AS4777 enabled and LOM disabled on the generator input (AC In 2), there is still a frequency range active that the AC input must fall within on initial connection, in my case, it is 47.5Hz up to 50.15HZ. Once connected, this range is then 47HZ up to 52HZ as per AS4777. I was unaware there were two frequency ranges, it was not in any documentation I read and this information would of been useful at the start.

As soon as the generator speed was reduced to within the frequency start range, and it was only ever so slightly, away it went.

Victron, you need to lift your game when it comes to after sales service.

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Paul B avatar image
Paul B answered ·

Hi Wesley, good to see you got it nailed - these sorts of things are hard to nail down on sites from time to time, and thats were these community discussions are so helpfull - you just have to remember all the tips :):):):):) - and there are a lot

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.