电流互感器饱和对风电场送出线纵差保护的影响及对策

目前风电等新能源应用越来越广泛,而风电场送出线路电流互感器的配置依旧采用常规的方法进行选型计算。当风电场送出线发生故障时,由于风电场呈现出弱电源特性,且输出故障电流含有大量的非周期分量使电流互感器易发生饱和现象,从而导致送出线路纵差保护误动。利用PSCAD和Matlab软件,针对风电场送出线路电流互感器的不同饱和情况分别进行了仿真分析。为了提高纵差保护的可靠性,给出在保护中采用改进递推两点乘积算法的措施。仿真结果表明,改进递推两点乘积算法能有效避免电流互感器饱和所带来的区外故障保护误动作的问题,且计算、动作时间更快,从而提高了送出线路纵差保护的可靠性和快速性。

Influences and countermeasures of the saturation of current transformer to the differential protection of wind farms' output transmission line

New energies, such as wind and electricity, have been widely applied. However, for the configuration of current transformer of the output transmission line in wind farms, people still do the lectotype calculation in conventional ways. When the output transmission line breaks down, the power supply of wind farms will be weak, and a large number of aperiodic components in the faulty current will be easy to make the current transformer become saturated, which will result in the malfunction of the differential protection. In the aim of improving the reliability of differential protection, we will use PSCAD and Matlab to conduct a simulation analysis on the different saturation situation of the output transmission lines, finding out the solutions to the improvements of the reliability of differential protection. The results of simulation show that the improved recursive two-point product method can effectively prevent external mal-operations caused by the current transformer saturation. Besides, the calculation and operation time of this method can be faster, which will enhance the reliability and improve the speed of the differential protection of the output transmission line. This work is supported by Natural Science Foundation of Shandong Province (No. ZR2016EEM13) and China Electric Power Research Institute Innovation Fund Project (No. XT83-17-002).