A Reactive Power Control Method Based on Dynamic Virtual Impedance for PV Micro-grid

In the AC microgrid system composed of photovoltaic, the inverter is connected to the large grid through the common connection point. Droop control is usually used to maintain the power balance and voltage stability of photovoltaic power supply point, and the voltage stability is realized by reactive power compensation. In the actual photovoltaic microgrid system, due to the transmission line impedance mismatch, there are errors in reactive power distribution. In order to solve this problem, this paper proposes a virtual impedance to improve the accuracy of reactive power distribution, specifically using dynamic virtual impedance to improve the resistance characteristics of the system and compensate for voltage drop. Aiming at the transient impact caused by the voltage surge caused by load removal in photovoltaic microgrid, the changes of active and reactive power are analyzed, and a reactive current control strategy is proposed to stabilize and consolidate the bus voltage. The above strategies are verified by Matlab / Simulink simulation and experiment to verify that the proposed scheme can effectively improve the control performance of photovoltaic microgrid.