I am working on voltage control of a Standalone DC Microgrid consisting of Single PV source, a battery and loads. The PV is interfaced through Buck converter to the DC bus, the battery is interfaced through Bidirectional DC-DC Converter(BDC) and the loads are directly connected to the DC bus. The aim is to maintain DC bus voltage at a reference value irrespective of variations in PV power and load power. Battery plays a key role in balancing the power and maintaining the voltage in the system. Accordingly I have designed a simple cascaded PI control(outer voltage loop control and inner current loop control) for BDC, such that the DC bus voltage and power balance is maintained. This control is working well and fine for all cases when SOC of battery is in between the limits (20% < SOC < 80%)
The problem which I am facing is that if I choose an initial SOC of battery as 85% (or one can assume that battery SOC has reached >80%) and in that situation I got PV generating more than load requirement for some time. In other times the PV power is less than load. When the case of excess PV power generation I thought of designing a logic to stop switch the BDC and moving the PV from MPPT (off-MPPT) and operate it. But the problem here is that the PV should itself do the voltage regulation and power balance. I couldn't achieve this properly inspite of my efforts. Please give some specific suggestions on the method to solve this problem.
PS: Sorry for a long question. Thank you in advance for your patience in reading it.
I recommend you to study this article
"A Hybrid MPPT method for grid connected photovoltaic systems under rapidly changing atmospheric conditions"
Malyala Venkata Satya Sai Chandra
hello, have you solved your problem ?
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