有功指令共享下的两级式光伏VSG并网系统故障穿越策略OA

To address the issues in traditional two-stage grid-connected photovoltaic(PV)systems based on virtual syn-chronous generators(VSGs)such as unclear active power commands,slow PV power regulation and excessive short-cir-cuit current,a fault ride-through strategy that shares active power commands with a supercapacitor is proposed in this paper.Under this strategy,the maximum active power command that the grid can withstand during a fault is calculated and further distributed to both the active power-frequency loop of a PV inverter and the control loop of the supercapaci-tor,thereby achieving the active power command sharing.The active and reactive power control loops are coordinated to maintain power angle stability and suppress the short-circuit current.Meanwhile,the structure of supercapacitor control loop is improved to stabilize the DC bus voltage and absorb the surplus system energy.Simulation results demonstrate that the proposed strategy effectively suppresses the short-circuit current,maintains the stability of power angle,virtual rotor speed and DC bus voltage,and enhances the system's response capability to fault disturbances,providing an ef-fective scheme for ensuring the safe and stable operation of grid-connected PV systems under fault conditions.