Trying to peak shave PV output via BESS but i cant figure out the control system.

Hello,

I am trying to make a BESS either charge, discharge or be at standby depepnding on the output power from a PV array. The charging and discharging are dependent on, if the output power either increase or decrease, so if it increases the bess will charge to lower the output peak and vice versa....

I have made a PV array boost converter and mppt, and i have a bidirectional DC/DC converter. These have a common DC-Bus where i want the output power to be smoother. But i simply cant work out the control or how i am going to do it... Does anybody have anything like this that works i might be able to look at?

I have added a picture my simulink model.

How can i make this battery be able to either charge, discharge and be at steady state at different times via some kind of control?

Best Regards

Peter

Answer 1

[Joel Van Sickel]

A good starting point is to come up with a supervisory controller that will provide set points to the different systems. You will typically want most or all of your systems to take current commands (to control power flow) but you may want one of your systems to maintain the dc link bus voltage. The solar panel converter comands are already being handled by MPPT, so you need to decide how to control the dc/ac converter, and the battery dc/dc converter. There are multiple ways to do it and in this drawing, since there is an ideal three phase source, I would use that system for stabilizing the voltage, and then use current commands to control power flow from the battery and the solar panel. This is far from the only control scheme that could do this, but hopefully it gives you a starting point to try something. If you have a current controller on the battery , you can control power flow directly by controlling current flow, and the dc/dc converter is well suited to current mode control techniques.