Research on the Control Technique of Low Voltage Ride-through for Grid-connected Photovoltaic Inverter

According to the new requirements of large-capacity MW solar power station, this paper establishes a mathematical model of the inverter, analyzes the drawbacks of synchronous reference frame phase-locked loop in low voltage ride through, improves the performance of decoupled dual synchronous reference frame phase locked loop and designs the proportional integral controller parameters. It uses the feed-forward decoupling, grid voltage feed-forward control and coordinated control in current control loop. The experiment results show that the proposed control techniques can make the three-phase photovoltaic grid-connected inverter operate stably and reliably under low voltage ride through condition, and make the inverter meet the relevant standard requirements. This proves the validity and feasibility of the proposed control technologies.