考虑三重因素的双馈风电机组撬棒电路保护控制策略分析

Crowbar Protection Control Strategy of Doubly-fed Induction Generator Considering Triple Factors

撬棒(Crowbar)电路作为提高双馈风电机组低电压穿越能力的主要措施之一,其控制策略的选取对风电机组动态特性影响较大。针对电网故障持续时间、机端电压跌落深度以及故障时刻风机运行状态三重因素,在Matlab/Simulink平台上搭建含Crowbar电路的双馈风电机组模型,通过对转子侧电流分析,验证了这三重因素对转子侧电流的影响。仿真结果表明,在电网故障持续时间较长、电压跌落较深、风机运行点较高时应采用Crowbar阈值投入故障清除后延时退出的控制策略,相反则应选择Crowbar阈值投入延时退出的控制策略,并给出Crowbar动作区域曲线和Crowbar控制策略选择区域曲线,明确两种控制策略的适用范围,初步得到了Crowbar保护控制策略。

Crowbar protection circuit as one of the main measures to implement the capacity of low voltage ride through （LVRT） of doubly-fed induction generator （DFIG） ,the selection of its control strategy has great influence on the dynamic characteristics of wind turbines.By analyzing the rotor current via a simulation model of DFIG with crowbar circuit built on Matlab / Simulink platform, the influence of the three factors including the duration of the fault,voltage drop levels and DFIG operating state during the LVRT is evaluated.The simulation results show that crowbar circuit should follow the control strategy of threshold input and delayed exit after the fault clearing in case of long duration of grid failure, deeper drop of the voltage and higher point of DFIG operating.Conversely,the control strategy of threshold input and delayed exit should be adopted.The crowbar action area curve and crowbar control strategy selection area curve are provided.The scope of application of the two control strategies are identified clearly and a crowbar protection control strategy of doubly-fed induction generator obtained.