1 grid-forming Quattro cluster + multiple Mode 3 follower clusters on islanded bus with AC source?

DIY
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1

Hi all,

I’m looking for guidance/experience with a fully islanded system using several independent three-phase Quattro battery systems on one common AC bus.

The proposed arrangement is:

  • 3 independent BESS clusters
  • Each cluster has 3 × Quattro 48/10000/140-100/100 120 V, configured as a three-phase 120/208 V VE.Bus system
  • Each cluster has its own battery bank and Cerbo GX
  • BESS #1 would be the designated grid-forming / black-start system
  • A small DC generator is connected to the DC bus of BESS #1, together with its battery bank
  • BESS #2–#3 would operate as grid-following systems
  • An external controller would provide active-power, and ideally reactive-power, commands to BESS #2–#3
  • The common 120/208 V islanded AC bus also has:
    • AC-coupled PV inverters (grid following)
    • an AC-coupled wind inverter (grid following)
    • site loads

I understand that the current s97 Victron Microgrid / Hybrid Droop application is intended for multiple Victron Power Banks sharing the bus through droop control, but the current documentation does not support AC-coupled PV/wind or other additional AC generation on that same Microgrid bus.

Because PV and wind need to remain connected to the common AC bus, I am investigating whether a master/follower architecture using standard VE.Bus / ESS Mode 3 is a better approach.

I would really appreciate input on the following:

  1. Has anyone successfully operated one Quattro system as the island grid-former and multiple completely independent Quattro systems as grid-following followers using ESS Mode 3 or another external-control method?
  2. For that architecture, would the normal arrangement be:
    • grid-forming system supplying the common bus from AC-OUT-1
    • follower systems connected to the same bus through their AC-IN?
  3. Can the follower systems be reliably commanded to charge/discharge through their AC-IN while another independent Quattro system is forming the bus?
  4. Has anyone operated this type of master/follower arrangement with AC-coupled PV or wind on the same bus?
    • Were there stability problems when the grid-forming Quattro used frequency shifting?
    • Is direct external curtailment of the PV/wind inverters preferable to frequency shifting in this type of system?
  5. For Quattro 48/10000/140-100/100 120 V, which firmware path would be appropriate for this architecture?
    • standard firmware such as 2754556.vff
    • or 2754561-s97.vff with Microgrid operation disabled
  6. If s97 firmware is installed but Microgrid operation is disabled, can the system use the ESS Assistant / Mode 3 external-control functions, or does the s97 requirement for Grid Code “None” prevent that?

I have found a few Community discussions where a central inverter forms the island and other ESS systems operate as externally controlled followers, including Mode 3 examples, but I’m trying to understand whether this can be made reliable with multiple three-phase follower systems plus AC-coupled renewables on the same island bus.

Thanks in advance for any practical experience or guidance.

4

Because it is big power and not DIY level thing it is best to work through the main sales a distribution centre
So do that.

https://www.victronenergy.com/where-to-buy?continentid=1

The forum is not a place for design either. Especially not at this scale.

Many of your questions are already covered in the manual

The microgrid is not AC PV ready in any case. It is recommended to use DC PV for each bank separately. And they don’t share power over the bus.

5

Thanks, LX. To narrow it down to one specific question:

Is ESS mode 3 appropriate and supported method for operatring independent Quattro BESS clustures as an externally commanded P/ Q grid following units, where one Quattro BESS forms the islanded AC bus through AC-OUT and other BESS clusters connect to that bus through their Quattro AC IN terminals? If so, can the external controller command active power P and reactive power Q for follower clustures when AC coupled sources, also supervised by external controller, are connected to the same bus?

6

It is not designed to work like that.
Please consult a qualified supplier for this scale system.
Thanks for understanding.