电网电压骤升时DFIG定转子电流分析及无功电流配置改进

Analysis of DFIG Stator and Rotor Current Improvement of Reactive Current Configuration in Case of Grid Voltage Swell

在双馈感应发电机(DFIG)高电压穿越(HVRT)问题中,电压骤升引起的暂态过电流不足以触发撬棒保护动作,致使HVRT下的定转子短路电流特性比低电压穿越(LVRT)更复杂。推导了计及电磁暂态过渡过程和转子侧换流器(RSC)调控共同作用影响下的定转子电流表达式。在此基础上考虑并网规范要求的DFIG无功电流支撑,控制RSC和网侧换流器(GSC)输出与骤升幅度相对应的分量,使DFIG工作于无功支持状态。仿真结果表明,定转子电流表达式准确描述了HVRT期间的故障电流,所得结果更具一般性,且对故障电气量的计算具有重要意义;改进无功电流配置实现了DFIG的HVRT。研究结果对掌握DFIG的动态过程具有一定的参考价值。

In the problem of high voltage ride through(HVRT)of doubly-fed induction generator(DFIG),the transient overcurrent caused by voltage swell is not enough to trigger crowbar protection action,which makes the short-circuit current characteristics of stator and rotor under HVRT more complex than those in the case of low voltage ride through(LVRT).Different from the inherent analysis of stator and rotor current,the expressions which take into account the combined influence of electromagnetic transient transition process and rotor side converter(RSC)regulation are derived.On this basis,considering the requirements of grid connection specification for DFIG reactive current support,the outputs of RSC and grid side converter(GSC)related to the swell amplitude are controlled,so as to make DFIG work in the reactive support state.The simulation results show that the expressions of stator and rotor current accurately describe the fault current during HVRT,and the results are more general and are of great significance to the calculation of fault electrical quantity.The improved reactive current configuration realizes the HVRT of DFIG.This research has a certain reference value for mastering the dynamic process of DFIG.