双馈风电机组短路电流特性分析

Short Circuit Current Analysis of DFIG

提出了一种分析计算双馈风电机组(DFIG)短路电流的新方法。该方法结合了物理过程分析和频域计算法的优点,根据物理过程分析法,可以将故障后的DFIG频域方程分解为零状态响应和零输入响应。通过求解各响应的方程式,可以得到短路电流的解析计算表达式。通过对比对称和不对称故障下短路电流表达武,电网对称性故障下交流分量会快速衰减完,不对称故障下交流分量会最终达到一个稳定值。最后通过仿真验证了对称性和不对称性故障下短路电流表达式的正确性。

A new method of analyzing and calculating fault current of DFIG is presented,which combines the advantages of physical process analysis and frequency domain analysis.According to the physical process analysis,the frequency domain equation of DFIG is divided into several equations about zero state and zero input response.By separately solving the several equations,formulas for the calculation of fault current are deduced.Based on this method,the fault current characteristics of DFIG under symmetrical and unsymmetrical fault are compared.Comparison result shows that AC component of fault current of DFIG under symmetrical fault soon decays end.But AC component under unsymmetrical fault is stable at the end.Simulation results show the validity of proposed formulas under symmetrical and unsymmetrical fault.