Hello,
I’ve got a new issue with my setup which wasn’t occurring before.
I have 3x 10kw MP2, 80kw of batteries; running latest firmware’s and Cerbo early release.
In the past, if the grid cuts out my system would act as big UPS and buffer any drops or dips in voltage.
However having just had a grid power cut, I found that the system had a big drop (at a load of 5kw) causing all computer systems and electrical devices to drop out and reboot.
Can anyone give me some idea what to look for as to why this is happening now?
FYI if I switch my MP2s to invert only, there is no issues (including when the grid drops).
So why is the drop happening when the MP2s are “on”.
What grid code and LoM are you using?
Does this occur if you manually trip the main breakers for grid?
Do you allow feedin to the grid?
If this was a grid brownout, were all three phases dropping or just one?
Looking at VRM grid power and grid meter data to see if anything unusual was happening.
What is the largest ripple you have observed in your system?
Were there any ripple or low battery alarms during this event?
Are you confident that there is sufficient battery capacity in the system? (sounds like it)
Have you measured round trip resistance or voltage drop from batteries to inverters?
Thanks for your reply.
Grid Code - G99 - UK
LOM - just inverter detection; no islanding. LOM B type
Yes feed into grid is allowed
Thus far I’ve only noticed the drop when 3 phases are all lost. I can re-create it by manually turning the isolator to the grid’s supply off. It seems like the UPS function is very slow to kick in.
I’ve got no ripples at all, nothing on the logs, alarms, events. Everything appears to be normal for the voltage until the grid drops.
Battery supply is perfectly fine - as mentioned this issue never used to occur, and as long as the MP2’s are pre-selected into invert mode this issue doesn’t happen which suggest the system is all fine, but the MP2 just can’t respond quickly?
Ok, the reason I asked is because I had a problem here where I could not reproduce the same issue by manually isolating the grid. I ended up adding external DC capacitance near the inverters to get through grid brownouts. Doesn’t sound like that would help for you.
My impression based on other posts is that LoM and certain grid code settings really slow down the UPS function enough that this can happen. No warnings or errors, everything just drops.