I have been running a Victron Microgrid with Multiple independent systems as a Test for a larger system. Has anyone else done anything similar?
More Info: https://shaneyake.blogspot.com/2021/09/micro-grid.html
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Microgrid with multiple Nodes
This is very interesting, I've been considering the Idea of running multiple ESS on an islanded microgrid but am unsure how stable it would be. Don't have the means to investing in two more multiplusses and batteries to find out!
I've made a control algorithm to instruct each ESS shown below to help balance the grid and storage.
Yeah, it isn't that difficult till the Main system has SOC of 100% and you need to throttle down the export of the other units. That is the hardest part to get stable.
Okay nice that's encouraging, I'm thinking the main grid would be better using ultra capacitors and kept at 50% instead of providing any significant storage. I'm a fan of load banks to dump any excess when the ESSes are full.
You don't actually need to do that. I have implemented this with regular LFP at the master, you just don't bring it all the way to 100%, like 95% works fine.
But I do have communication between all the nodes, so the master can set export limits for the slave nodes in realtime. There is a way to do it with frequency shifting but I haven't been able to tune that to be perfectly stable.
The only issue with this type of system is that the grid forming node - the master system MUST have a power equal to that of the permitted reverse power of all the other nodes combined. This is needed to follow Victrons 1:1 rule for ac coupled systems. Given that restraint, there is no reason why this should not be made to work.
You actually don't have to follow the 1:1 rule. You just have to be able to handle the peak output for a few seconds till you can ramp down the nodes.
The master node has to be bigger than any of the slave nodes but does not need to be equal to all slave nodes. I have tested this and it is stable.
