基于主动式Crowbar的双馈风电机组LVRT性能优化分析

面对短路故障引起的电压大幅跌落,为避免直接脱网对电网造成的不利影响,双馈感应风电(DFIG)机组多采用撬棒保护电路(Crowbar)实现低电压穿越(LVRT)功能。文章利用磁链平衡原理对含Crowbar电路的DFIG三相短路电流简化表达式进行推导,提出旁路阻值的优化整定方法。为验证整定方法的有效性及Crowbar退出时间对LVRT性能的影响,利用PSCAD/EMTDC平台对电压骤降情况下DFIG的LVRT性能进行了一系列仿真分析,结果表明:在确保网侧变流器正常工作的前提下,Crowbar阻值在整定范围内取偏大值且Crowbar在故障清除1个周波后退出运行,会使DFIG得到更好的LVRT效果。

Analysis on LVRT Performance Optimization of DFIG with Active Crowbar

For DFIG-based wind turbines,Crowbar is commonly used as protection method against sudden drop of the grid voltage caused by short-circuit fault during the period of LVRT(Low Voltage Ride Through).Based on flux linkage balance principle,the simplified expression of three-phase short-circuit current for DFIG with the crowbar circuit is deduced,and optimized setting method of the resistor for bypass circuit is presented.To verify the effectiveness of setting method and the influence of exiting time of crowbar on the performance of LVRT,the performance of LVRT for DFIG under voltage sudden drop are simulated and analyzed by using of PSCAD/EMTDC.The results show that when the larger value of crowbar resistance is selected in the setting range and the crowbar is out of operation after fault being cleared in a cycle,DFIG can obtain better LVRT performance.