串联补偿对差动保护的影响分析

根据冀北地区万顺500 k V特高压输电线路建立模型,分析串联补偿线路出现"电流反向"问题的根本原因和可能性。结合万顺具体算例,研究串补线路中差动比例系数K值在不同故障点、串补度、经高阻接地和MOV是否被击穿等情况下的变化趋势。代入现状运行方式下的具体参数,通过RTDS对模型进行数字模拟实验,深入探讨单双回串补线路运行状况下串联补偿对零序差动和分相差动保护动作特性的影响,得出过渡电阻、故障点、系统参数以及负荷变化等情况的差动保护动作结论,并给出万顺串联补偿线路保护装置的合理改进建议。

Research on influence of series compensation on differential protection

This paper analyzes the primary causes and its possibility of the reversed current in serial compensation lines, according to the model of Jibei Wanshun 500 kV ultra-high voltage transmission line. Besides, the variation tendencies of differential protection ratio coefficient K of serial compensation lines on the condition of at different failure points, degrees of series compensation, grounding circumstances via high resistance and MOV breakdown are discussed by specific cases in this study. Practical variables under current operation mode are taken into simulation by RTDS. The performance characteristics of zero-sequence differential and phase difference protection affected by serial compensation are presented under single/double line operation modes. Since then, the performances of differential protection with variant transient resistance, failure points, systematic variables and load are obtained, furthermore, the improvements of Wanshun serial compensation protection devices are recommended at the end.