基于新型转子撬棒的双馈风电机组低电压穿越技术

The low voltage ride through of dfigs based on new crowbar

针对目前双馈风力发电系统低电压穿越方案所存在的问题,尤其是转子侧投入撬棒后在穿越过程中的一些不足,提出了一种新型的阻容式转子撬棒以改善双馈风力机组的低电压穿越能力。在分析了双馈风力发电机故障期间投入撬棒后特点的基础上,结合其对应的等效电路,推导出双馈风力发电机定子侧与转子侧的无功功率表达式。对无功功率表达式定性分析后,得出提高低电压穿越能力的方案,并以此设计出一种不同于传统撬棒的新型转子撬棒,即阻容式转子撬棒。利用MATLAB/simulink搭建仿真模型进行验证,仿真结果表明:新型阻容式转子撬棒不仅可以在定子侧加快故障电压的恢复,而且可以限制转子侧过电流,抑制因撬棒的投切而对机侧变流器的暂态冲击,最终实现了有效提高双馈风力发电系统低电压穿越能力的目的。

Aimed at the problems of LVRT for DFIGs system,especially some drawbacks after crowbar is used in rotor side,a new RC-crowbar is proposed to improve the LVRT ability.Based on analyzed the characteristics of DFIG during fault,combined with the corresponding equivalent circuit,and the reactive power expression of stator side and rotor side are derived for DFIG.After qualitative analysis of the reactive power expression,a scheme for improving the LVRT of DFIG is proposed,and then a new type of rotor crowbar is designed that is different from the traditional crowbar,namely RC-crowbar.Using the MATLAB/Simulink to establish simulation model,the simulation results show that the new type of RC-crowbar can not only speed up the recovery of fault voltage in the stator side,and can limit impact current in the rotor side,suppress the transient shock of RSC,the objective that is effectively increase the LVRT ability is aehieued.