电网电压不对称跌落下DFIG低电压穿越控制策略  

Low Voltage Ride-through Control Strategy for DFIG under Asymmetrical Grid Voltage Drop

作　　者：姜惠兰[1] 李希钰 贾燕琪 王绍辉[1] JIANG Huilan;LI Xiyu;JIA Yanqi;WANG Shaohui(Key Laboratory of Smart Grid of Ministry of Education,Tianjin University,Tianjin 300072,China)

机构地区：[1]天津大学智能电网教育部重点实验室,天津300072

出　　处：《电力系统及其自动化学报》2021年第12期27-33,42,共8页Proceedings of the CSU-EPSA

基　　金：国家自然科学基金资助项目(51477115)。

摘　　要：风电机组在电网电压不平衡下低电压穿越的能力提高是高风电渗透率系统安全稳定的重要保证。本文通过理论分析不对称故障情况下双馈风力发电机的暂态特性,得出转子感应电动势的暂态和负序分量是导致转子过电流的直接原因。进一步推导了不对称故障下定子电流微分与转子感应电动势暂态分量和负序分量的关联关系,基于此提出一种计及风机转子侧变流器容量限制的低电压穿越控制策略。基于转子电流对于转子感应电动势暂态分量和负序分量的敏感度,给出优先抵消使转子电流变化更灵敏的转子感应电动势暂态分量的方案,使得风机转子侧变流器有限的容量得到合理分配。仿真结果表明,所提方法能有效降低转子电流冲击,并最大程度抑制了二倍频分量。The improvement of the low voltage ride-through(LVRT)capability of wind turbines under unbalanced grid voltage is an important guarantee for the safety and stability of a system with a high wind power penetration rate.Through the theoretical analysis of the transient characteristics of a doubly-fed induction generator(DFIG)in the case of asymmetric fault,it is pointed out that the transient and negative-sequence components of the rotor induced electromotive force are the direct cause of rotor overcurrent.In addition,the correlation between the stator current differential and the transient and negative-sequence components of the rotor induced electromotive force under asymmetric fault is deduced,based on which a LVRT control strategy that takes into account the capacity limitation on rotor-side converter(RSC)is proposed.According to the sensitivity of rotor current with respect to the transient and negative-sequence components of the rotor induced electromotive force,a scheme is given to preferentially cancel the transient component of the rotor induced electromotive force that makes the rotor current change more sensitively,so that the limited capacity of RSC can be reasonably allocated.Simulation results show that the proposed method can effectively reduce the impact by rotor current and suppress the double-frequency component to the greatest extent.

关 键 词：双馈风力发电机 不对称故障 低电压穿越 控制策略 

分 类 号：TM71[电气工程—电力系统及自动化]