Common DC Bus on a Battery-Inverter system

[Xnikan]

Hi all,

This time I have different issue which is not very clear to me.

Let's say that I have a system with 5 Batteries and 5 Inverters (as it can it be seen on the photo) which are connected to the low voltage grid. For my application I would prefer to have a common DC Bus for all the batteries and the inverters (assumming that the inverters support this "parallel" operation). Let's also assume that the EMU (Energy Management Unit) of the system is capable of balancing the charging and discharging of the batteries.

I read somewhere that this configuration might increase very much the Common Mode Voltage (CMV). How that would happen? Do you see any other problems -electrically related- that might arise from that kind of system?

Thanks again

 

[itsmoked]

You have tied all the batteries together in parallel (well, sort of, since the dots miss in places

)

Tying the batteries together defeats a big part of any redundancy you have. If one battery loses a cell shorted it will take down all the other batteries as they try to balance with it. Well, at least until it explodes. You should not parallel them.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[FreddyNurk]

Your fault current is going to be spectacular with that arrangement too.
Also, assuming your system is bidirectional, unless you have the capability within the inverters, you'll end up with one unit doing all the work and the rest sitting idle, as they won't share the load or charging duties.
Any systems I've seen that have needed multiple strings in parallel for capacity have used load sharing capable units, there's nothing to gain if you don't have that capability.

EDMS Australia