中文摘要：

在系统故障期间,双馈式风电场电源的等值内阻抗会发生变化,给风电场送出线路距离保护的适用性带来了很大影响。讨论了双馈式风电场的电源特性和故障暂态特征,对采用电压极化的比相式距离保护的动作特性进行了分析。分析结果表明,当系统发生故障时,阻抗圆的时变特性会造成距离保护不正确动作。RTDS仿真试验验证了理论分析的正确性。

英文摘要：

The internal equivalent impedance of DFIG may change during the system fault,which obviously impacts on the applicability of distance protection for the outgoing transmission line of wind farm. The power source characteristics and fault transient characteristics of DFIG-based wind farm are discussed and the action characteristics of phase-comparison distance protection based on polarized voltage are analyzed.The analytical results show the time-varying impedance circle characteristic may cause the improper action of distance protection during the system fault and the results of RTDS simulation prove the correctness of theoretical analysis.