不同电压跌落深度下基于撬棒保护的双馈式风机短路电流特性分析  

Short Circuit Current Characteristics of Doubly Fed Induction Generator With Crowbar Protection Under Different Voltage Dips

作　　者：周宏林[1] 杨耕[1] 

机构地区：[1]清华大学自动化系,北京市海淀区100084

出　　处：《中国电机工程学报》2009年第S1期184-191,共8页Proceedings of the CSEE

基　　金：国家自然科学基金资助项目(60674096)~~

摘　　要：双馈式并网风力发电系统在低电压过渡(low voltageride-through,LVRT)时一般采用转子侧撬棒方法来抑制短路电流。在分析撬棒保护下双馈发电机(doubly fed inductiongenerator,DFIG)磁链暂态特性的基础上,给出分析最大短路电流的简化线性模型。指出由转子侧变流器续流二极管导致的直流母线箝位效应的存在,及其对短路电流的影响。对于短路电流的研究,提出一种考虑直流母线箝位效应的撬棒电阻选择方法。对1.5MW DFIG风力发电系统进行仿真,结果表明,当撬棒电阻选择较小或短路故障较轻时,不会出现直流母线箝位效应,简化线性模型能准确地评估最大短路电流;当撬棒电阻选择较大或短路故障较严重时,短路电流的评估必须考虑直流母线箝位效应。受该效应的影响,过度增大撬棒电阻不能明显改善过渡范围,反而会增大转子侧变流器续流二极管的负担。For wind turbines with doubly fed induction generator(DFIG),crowbar is a commonly used protection method against surge current caused by sudden drop of grid voltage during low voltage ride-through(LVRT) periods.Based on the detailed analysis of the transient flux characteristics of DFIG with crowbar fired,a simplified linear model was proposed to analyze and approximate the short circuit current accurately.Then the dc-link voltage clamp effect was pointed out and a crowbar resistance design method based on the dc-link voltage was proposed accordingly.A typical 1.5 MW DFIG wind turbine was used for case study.The analysis and simulation results show that,when the crowbar is small or the fault is not severe,the dc-link clamp effect does not occur so the linear approximate model can give a satisfactory approximation of the short circuit current;otherwise,the dc-link clamp effect must be taken into account in determining the short circuit current.In this case,excessive increasing of crowbar resistance would not improve the LVRT capability substantially,but putting more pressure on the fly-wheel diodes of the rotor side converter.

关 键 词：风力发电 双馈发电机 低电压过渡 撬棒保护 短路电流 

分 类 号：TM614[电气工程—电力系统及自动化]