考虑撬棒保护动作时间的双馈式风电机组短路电流特性

Short-circuit Current Characteristic of Doubly Fed Induction Generator Considering Crowbar Protection Insertion Time

撬棒(Crowbar)保护是否动作及动作时间会对双馈感应发电机(DFIG)短路电流特性产生影响。目前计及撬棒保护影响的相关研究均按照故障后撬棒保护瞬时动作来分析短路电流特性,但实际上机端电压跌落时,撬棒保护并非瞬时投入运行,而是根据故障严重程度带有不同的动作延时,这给短路电流的精确分析计算增加了难度。文中针对这实际问题,以机端发生不对称故障为例,将故障电流分解为正向和反向同步旋转坐标系下的正序和负序分量,并根据撬棒保护动作时刻将故障过程分解为两个阶段,通过数学解析的方法给出整个故障过程的短路电流计算表达式。通过与MATLAB/Simulink的DFIG标准模型对比,仿真验证了计算表达式的有效性,并分析了撬棒保护不同动作时间对DFIG短路电流特性的影响。

The activation of Crowbar protection and its action time both have impacts on the short-circuit current characteristics of doubly fed induction generator（DFIG）.Nowadays,most studies assume the instantaneous activation of Crowbar protection after the occurrence of voltage sag.However,in practice,the Crowbar protection acts with different time delay depending on the severity of the voltage sag,which complicates the precise calculation of the short-circuit current.Aiming at this practical problem,this paper takes asymmetrical fault occurred at the stator terminal as an example.The fault current is divided into positive and negative sequence component in the forward and reverse synchronous rotating reference frame respectively,and the fault process is divided into two stages according to the Crowbar insertion moment.The formula of the fault currents during the fault process is derived in detail,and compared with the standard DFIG simulation model provided by MATLAB/Simulink. The comparison results validate the proposed formula and the effect of insertion time on DFIG short-circuit current characteristics.