直 驱 风 机 低 电 压 穿 越 行 为 对 并 网 点 电 压 的 影 响 及 优 化 控 制

With the increasing penetration rate of wind power, its low voltage ride-through behavior has growing impact on the safe and stable operation of power grids. Based on massive field test data, low voltage ride-through response characteristics of direct-driven wind turbines are analyzed, and the whole low voltage ride-through processes are divided into low voltage ride-through process and recovery process. In the low voltage ride-through process, the impact of wind power penetration rate and its power characteristics on the recovery level of the voltage of the grid-connected point is discussed, and the fact is revealed that the delayed voltage recovery will lead to the loss of more wind power which further aggravates the frequency dip. In the recovery process, the sources of the voltage fluctuation caused by the reactive power control switching and reactive power recovery strategy are discussed, which may cause continuous low voltage ride-through and tripping accident of the wind turbine. To suppress the voltage fluctuation and achieve fast and stable voltage recovery, the optimal control strategy of low voltage ride-through for wind turbines are proposed. Finally, the simulation is conducted on PSCAD/EMTDC platform, and the results verify the impact of the low voltage ride-through behaviors of wind turbines on the voltage of the grid-connected point and the effectiveness of the proposed optimal control strategy of low voltage ride-through.