Online Overvoltage Prevention Control of Photovoltaic Generators in Microgrids

For grid-connected microgrids with high penetration of photovoltaic (PV) generation, overvoltage caused by reverse power flow is a major factor that limits PV power output. To tackle the challenge, this paper proposes a new online overvoltage prevention (OOP) control strategy to maintain PV terminal voltages within specified range while maximizing the PV energy yields. The proposed method is based on a precise active power limit prediction using the dynamic Thevenin equivalent. The active power output of PV array can be modulated in real time such that the voltage at a point of interconnection (POI) is always maintained within a specified range without triggering overvoltage protection. Simulation results using the IEEE 33-bus single-phase test system and IEEE 34-bus three-phase system have validated the effectiveness and accuracy of the proposed control method.