Firstly, based on the equal circuit of power grid with doubly fed induction generators (DFIG), the paper studies the frequency components of short circuit voltage and current in the place where the protection devices are equipped with. And the analyzing result leads to different frequency characteristics of voltage and current for wind farms during faults. Secondly, simulations based on Matlab/Simulink verifies the particular characteristics and yields the relationship between transition fault impedance and the characteristics of short-circuit voltage and current. Following the frequency’s feature of short circuit current, the reliability and adaptability of distance protection are analyzed. Finally, simulation results verify the adaptive failings of this traditional protection in wind farms, and the results also have some certain instructional significance to relay protection test. This work is supported by Science and Technology Project of State Grid Corporation of China (No. 52100113058M) and National High-tech R & D Program of China (863 Program) (No. 2012AA050203).%基于双馈风机风电场的电力系统等效电路研究了输出线路短路故障点保护设备安装处的电压电流的频率成分，得出了含风电场的电力系统短路故障时所特有的电压电流频率的不一致性。基于Matlab/Simulink仿真平台验证了频率不一致的特性，总结过渡阻抗与短路点电压电流频率成分之间的关系。分析了电压电流频率的不一致性对于距离保护所产生的影响，研究了距离保护及其测试在风电场中存在的适应性问题。最后，算例仿真验证了分析结果的正确性，从而为风电场继电保护的设置和测试工作提供参考。
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