Hello,
I want to enquire about a very specific scenario, and I was wondering if anyone had implemented it in OpenEMS.
Essentially, we need to connect 2x sets of inverters to the same battery cabinet (the reasons are related to specific grid-code restrictions on inverter capacity)
These are:
- On-grid inverter for charging the battery from the grid
- Off-grid inverter for powering large loads (EV charging)
The on-grid inverter is exclusively used to charge the batteries and the off-grid inverter is exclusively used to discharge to power the loads.
This is of course an unusual setup. It is not possible (for reasons of grid code/regulation) to size the on-grid inverter sufficiently large to power the load (and the load only runs for a few hours per day).
I am interested in how this can be controlled in OpenEMS. The typical Generic ESS component is not really suitable because of the fact that the 2x inverters operate quite differently.
The controller in the EMS would need to manage the charging schedule for the on-grid inverter.
The off-grid inverter could largely manage itself as its power output should be automatically managed through droop control.
I think that it would be possible to write a specific component to handle this, which takes references to the on-grid inverter, off-grid inverter and the battery cabinet. It is difficult to reason about how OpenEMS controllers would work in this setup.
Alternatively, OpenEMS could only manage the on-grid side (i.e managing the charging schedule), and the off-grid side could be automatically managed by the inverter itself.
I am interested to hear others’ perspectives on this topic. Maybe someone out there has implemented something similar before.