双馈感应发电机(doubly fed induction generator，DFIG) 因其对电网故障的敏感性，其低电压过渡(low voltage ride-through requirement，LVRT)控制技术一直是国内外研究的热点。在分析电网故障时DFIG产生转子过电流机理的基础上，对采用串联网侧变换器(series grid-side converter，SGSC)的新型DFIG系统提出了电网电压正常时的“零电压矢量”改进控制策略及电网故障时保持DFIG系统不脱网运行的故障改进控制策略。所提故障控制策略从限制定子磁场暂态直流分量和负序工频分量及减小从风机吸收能量的角度出发，通过控制串联网侧变换器抑制定子磁链暂态直流以及负序分量对发电机转子侧的不良影响，通过控制转子侧变换器(rotor-side converter，RSC)进一步限制故障时的定、转子电流，从而实现DFIG系统在电网故障时的低电压过渡运行。在电网对称和非对称短路故障条件下，对一台采用SGSC的2 MW DFIG系统进行了仿真研究。并与采用传统“crowbar protection”方案和改进励磁控制策略方案的DFIG在电网故障时的不脱网运行能力进行了对比。仿真结果表明，所提控制方案可实现电网故障时DFIG系统的零电压过渡运行，系统具有良好的低电压过渡控制功能。

Doubly fed induction generator (DFIG) is very sensitive to grid faults. Its low voltage ride-through (LVRT) technology attracts more and more attention in recent years. The reason for rotor over current was analyzed in this paper. On the basis of this and combined with the new configuration of a DFIG system with series grid-side converter (SGSC), a “zero voltage vector” improved control strategy during normal grid condition and an improved fault control strategy allowing DFIG to ride through the grid faults were proposed. By controlling the output voltage of SGSC to suppress the transient DC flux and negative sequence flux components in the stator flux and also by controlling the rotor-side converter (RSC) to further restrain the stator and rotor currents, a successful ride-through during grid faults was achieved. Simulation on a 2 MW DFIG system with SGSC under symmetrical and unsymmetrical grid faults was performed. The LVRT performance of the proposed control strategy was also compared with the traditional “crowbar protection” strategy and the improved excitation control strategy. Simulation results demonstrate that the proposed control strategy can make the DFIG system with SGSC achieve zero voltage ride-through. The DFIG system has good LVRT performance.

国家高技术研究发展计划项目(863计划)(2007AA05Z422)；重庆市科委科技计划项目攻关项目(CSTC 2008AB3047)。