基于直接磁链跟踪控制的无刷双馈电机无Crowbar对称低电压穿越方法

Crowbarless Symmetrical Low-voltage Ride Through Method for Brushless Doubly Fed Induction Generators Based on Direct Flux Tracking Control

低电压穿越(low-voltage ride through,LVRT)能力是并网型风电机组重要的性能指标之一。该文提出一种基于直接磁链跟踪控制的无刷双馈感应发电机(brushlessdoubly fed induction generator,BDFIG)无Crowbar对称低电压穿越方法。该方法基于开关表,通过直接选定电压空间矢量来控制无刷双馈电机控制绕组(control winding,CW)磁链的幅值和相位,以迅速抑制低电压穿越期间控制绕组的感应过电压和由此导致的过电流,同时快速向电网注入动态无功电流以支撑电压恢复。该方法无需坐标变换、系统结构简单、磁链动态响应迅速。样机实验结果表明,低电压穿越过程中,有功恢复及无功功率动态响应满足国标相关要求,且控制绕组电流得到有效抑制,验证了所提控制策略的有效性。

Low-voltage ride through(LVRT)capability is one of the most critical performance indicators for grid connected wind turbines.In this paper,a crowbarless symmetrical LVRT method for brushless doubly fed induction generators(BDFIG)based on direct flux linkage tracking control is proposed.Based on the switch table,the method controls the amplitude and phase of the BDFIG control winding(CW)flux linkage by directly selecting the voltage space vector,so as to suppress the induced overvoltage rapidly,causing overcurrent in the CW during LVRT,while rapidly injecting dynamic reactive current into the grid to support voltage recovery.The method requires no coordinate transformation,with the advantages of simple system structure and quick flux dynamic response.The experimental results show that during the LVRT,active power recovery and reactive power dynamic response meet the relevant requirements of the Chinese national standard,and the CW current is effectively suppressed,which verifies the effectiveness of the proposed control strategy.