Fault ride-through control strategy for solar grid-connected inverters

Based on the control system of high-power solar grid-connected inverters, an adaption fault ride-through control strategy was proposed for fault gird conditions in this paper. The strategy is based on high-power grid-connected solar inverter topology using LCL active damping control, and analyzes the steady-state performance by establishing system models. The paper analyzed the operation status during fault grid voltage conditions in detail, then proposed a fault ride-through control strategy to solve the fault detection, phase synchronization and unbalanced grid fault problems. Finally, the control strategy was based on 500 kW grid-connected solar inverters to conduct Matlab/Simulink simulations and field experiments. The results show that the control strategy can suppress the negative sequence current so effectively and keep current high degree sinusoidal under different fault conditions that it can achieve secure ride through. The proposed control strategy successfully passed the LVRT certification test of the State Grid Electric Power Research Institute. © 2014 Chin. Soc. for Elec. Eng.