双馈风电短路电流特性对距离保护的影响分析

摘要

The short-circuit current characteristic of doubly-fed wind turbine is different from traditional synchronous motor,which brings new problems to algorithms and principles of protection.The deviation expression of the full-wave Fourier algorithm caused by speed frequency components is deduced,and the impact of double-fed wind turbines short circuit current on the full-wave Fourier algorithm is analyzed.Then simulation demonstrates the correctness of theoretical analysis.Meanwhile considering that wind farms are generally weak fed,for distance protection,taking into account different types of ground faults and different value of transition resistance,measured impedance of distance protection of wind farm feeders is calculated and verified by simulation using the DIgSILENT software.The impact of speed frequency short-circuit and weak fed character of doubly-fed wind farm on distance relay are analyzed and the pattern of measured impedance of distance relay varying with the speed frequency current is revealed.The conclusion can provide reference for the protection and configuration of wind power connect-in system.%双馈风电机组短路电流特性不同于传统同步电机,给继电保护算法和原理带来新的问题.解析推导了转速频率分量使全周傅里叶算法产生计算偏差的表达式,进一步分析了双馈型风电机组短路电流对全周傅里叶算法的影响,并通过仿真论证了理论解析的正确性.同时考虑到风电场一般具有较强的弱馈性,以距离保护为例,考虑不同类型接地故障并计及过渡电阻,对风电场侧送出线距离保护测量阻抗进行了机理分析,并辅以DIgSILENT仿真验证,分析了双馈风电短路电流中的转速频率分量以及风电场弱馈特性对送出线距离保护的影响,揭示了转速频率分量对于距离保护测量阻抗的影响规律.所得结论可为风电接入系统的保护与配置提供参考.