多串补线路保护动作性能分析

从理论上分析了多串补线路故障后的电气量特征,随着故障点的变化,线路多处会发生电流反相和电压反相,故障后电气量中存在多个低频暂态分量。研究了线路保护(电流差动保护和距离保护)的动作性能,提出了串补线路保护配置方案,并给出2点改进建议:一是采用保持记忆电压作为距离保护的极化电压,防止电压反相造成距离保护误动作;二是通过比较故障电流和记忆电压的相位来识别电流反相,当故障后电流相位超前记忆电压,判断为电流反相,闭锁电流差动保护。利用RTDS系统搭建了1 000 kV输电线路模型并进行了仿真验证,仿真结果与理论分析一致。

Analysis on Protection Performance of Transmission Line With Multi Series Compensation Capacitors

The post-fault characteristics of electrical quantities in transmission line with multi series compensation capacitors are theoretically analyzed.With the change of fault location,voltage reversal and current reversal will occur in different places along the transmission line,so multi low-frequency transient components exist in the post-fault electrical quantities.Based on the analysis on protection performance of current differential protection and distance protection for transmission line with series compensation capacitors,a protection configuration scheme for this transmission line is proposed and two improvement suggestions are given: one of which is adopting the memory voltage as the polarization voltage for distance protection to prevent the malfunction of distance protection due to voltage reversal;anther of which is recognizing current reversal by comparing the phase of fault current with the phase of memory voltage,when the phase of post-fault current takes lead in the phase of memory voltage,the current reversal is confirmed and the current differential protection must be locked.The RTDS based simulation of 1000kV transmission line with multi series compensation capacitors is performed,and simulation results conform to that of theoretical analysis.