Low-voltage Ride-through Control Strategy for Grid-connected Photovoltaic Power Generation System

Based on the requirement of low voltage ride-through capability of the new energy grid-connected power generation system under grid fault conditions, taking suppressing the negative sequence current as the control target, the control model of the two-stage optical storage grid-connected power generation system under the αβ coordinate system is established. The pre-stage photovoltaic system adopts a variable power trajectory tracking control strategy based on layered voltage to ensure the stability of the DC bus voltage and the output power of the photovoltaic system during fault crossing. Simultaneously, the stability of the system under frequency offset conditions and system's anti-disturbance capability can be enhanced by using a control strategy with grid voltage feed forward for double closed-loop quasi-proportional resonance strategy on the post-stage grid-connected inverter. The reactive power priority control strategy is used to support the recovery of the grid voltage during the fault by using the improved phase-locked loop module, this module can Synchronization of grid voltage signals under complex conditions and control the magnitude of the reactive power generated by the inverters. Finally, simulation module is built in Matlab/simulink under the fault conditions of frequency offset, phase jump and voltage asymmetry to verify the effectiveness of the proposed method.