We have seen a lot of Low Voltage warnings and Alarms on this Plant, and I think I understand what is going on here.
Initially, we suspected excessive resistance of the battery cables and fuses, but our calculations show this to be around 10mΩ.
That would only result in 1V drop from the battery to the VE.Bus at 100A, which is way less than drop that the logs for 21 Sept show (see attached graph).
Looking closely at the sequence of events around 05H35, it is clear that the VE.Bus voltage drops sharply just after the SoC setpoint of 40% is reached, and then immediately recovers. It's not a battery current problem, as that was even higher at 05H01.
So what I think is happening is that the transition from Battery power to Grid power has a dead band that is too long for the inverter's internal reservoir capacitors to sustain the VE.Bus rail voltage.
To fix it, there are two options:
- increase the capacitors (not viable in this case)
- reduce the dead-band with a firmware update
Please advise,
