提升直驱型永磁风电机组故障穿越能力的改进控制策略研究

A coordinated control strategy for fault ride-though capacity of direct-drive permanent magnet wind power generating units

为了提高直驱型永磁风电机组故障穿越能力,提出一种新的故障穿越策略。通过采用紧急变桨技术,减少故障期间风机的出力,降低直流母线两端的功率不平衡,以限制直流母线过电压。提出一种新颖的控制直流母线侧电容器投切方案,故障期间增加直流电容容量,进一步限制故障期间直流母线电压骤升。充分利用风电机组的无功能力,网侧变流器采用电压控制模式,为系统在故障期间提供无功支撑。给出了详细的故障穿越方案,并在仿真软件DIg SILENT中建立仿真模型,设计了低电压故障和高电压故障两个算例。仿真结果表明,所提出的控制策略可有效的限制故障期间直流母线过电压,为系统提供了足够的无功支撑,协助并网点电压快速恢复,提升了风电机组的故障穿越能力。

To improve the direct-drive permanent magnet wind turbine fault ride-through capability, a new coordinated control strategy for enhancing the fault ride-thought（FRT） is proposed, which adopts emergency pitch technology to reduce wind turbines＇ output during fault, and to reduce the active power deviation of the DC-link. A novel DC-link parallel capacitors control strategy is adopted to provide means for power evacuation during grid fault conditions, and then limit the fault during the DC bus voltage swell further. In order to make the reactive power control capability of PMSG, the grid-side converters are utilized to provide reactive power for the grid prior to operating the voltage control mode. A detailed FRT control strategy is given, and a simulation model is established by DIg SILENT. The results verify that the coordinated control scheme not only limits the DC bus overvoltage, but also provides certain dynamic reactive power supporting to the grid, which has a fine effect for the wind farm achieving the low/high-voltage ride through capability during grid fault.