An Active/Reactive Power Control Strategy for Photovoltaic Power Station Under Grid Fault

Grid-connected photovoltaic (PV) systems are usually supposed to provide voltage support during grid faults to help the recovery of power system from voltage sags. This paper investigates the optimized distribution of active and reactive power of grid-connected PV system in case of balanced grid fault, with the purpose to provide maximum grid voltage support during fault conditions. Taking the grid impedance into consideration, the principles of voltage support during grid fault are analyzed in detail, which revealed that the maximum voltage support can be achieved by injecting active and reactive current proportional to the R/X ratio of the equivalent grid impedance. Meanwhile, it can be observed how the penetration level of PV systems exerts influences on the voltage support effect. Several scenarios of simulation are conducted to verify the theoretical analysis.