永磁直驱风电机组故障穿越优化控制策略研究

永磁同步发电机构成的直驱型变速恒频风力发电系统通过全功率变流器与电网连接,当电网发生严重故障时,不仅对HVDC设备造成损害,甚至可能影响风力发电系统的整体安全稳定运行。对系统故障期间直流电压失稳的机理进行了分析,基于永磁同步发电机转子的惯性储能特性以及网侧换流器的无功补偿能力,提出一种适用于提高永磁直驱风电机组故障穿越能力的优化控制策略。在网侧故障期间通过分段式转速控制调整风机侧输入的有功并对网侧无功进行补偿,减小了中间直流系统注入的不平衡功率,抑制了故障期间直流电压的骤升。应用PSCAD/EMTDC电磁暂态仿真软件建立单机系统模型,仿真结果验证了所提出的控制策略的有效性。

Research on the fault ride-through optimal control strategy of PMSG-based wind turbine

The directly-driven variable speed constant frequency wind power generation system, which consists of the permanent magnet synchronous generator (PMSG), is connected to the grid by full size power converters. When severe faults occur in grid, the faults would not only cause serious damage to HVDC devices, but also have an adverse impact on the stable operation of overall wind power generation system. The disability mechanism of DC voltage during faults is analyzed. Based on the inertial energy storage characteristics of PMSG rotor and the reactive power compensation capability of grid-side converter, a novel coordinated control strategy aimed at improving the fault ride-through capability of PMSG is proposed. In order to decrease the imbalance power injected to the DC-link and suppress the overvoltage of DC-link, the proposed control strategy adopts an optimal generator-side segmented rotor speed controller to adjust the active power from wind turbine and increase the reactive power to grid on the basis of the grid-side converter with reactive power adjusting capability. A single-machine infinite-bus power system model in PSCAD/EMTDC is used to validate the effectiveness of the proposed control system for improving the fault ride-through capability of PMSG.