Low Voltage Ride-through of PV System Based on APFF

Aiming at problems of two-stage photovoltaic (PV) grid-connected system including inverter overcurrent and large fluctuation of DC-side capacitor voltage when the grid voltage drops, a low voltage ride-through optimization control strategy based on active power feed forward (APFF) mode is proposed. This mode is relied on the principle of two-stage PV system max power point track and double PI grid-connected control strategy. The key of mode is to calculate active power reference of inverter and a proper duty cycle of DC/DC converter to adjust the output power of PV array to maintain the power balance of the first-stage and second-stage modules at the moment of power grid voltage sags. This strategy can implement current limitation, inject reactive power to grid and suppress fluctuation of DC side capacitor voltage. Finally, the correctness and effectiveness of the proposed strategy are verified by MATLAB/Simulink.