串补电容引起的次同步谐振对距离保护的影响

Influence of Series Compensation Capacitor Caused Subsynchronous Resonance on Distance Protection

基于实际系统参数搭建仿真模型,通过模拟仿真并观测保护测量阻抗的轨迹图,研究次同步谐振对距离保护的影响。研究表明,次同步谐振对距离保护Ⅰ段有影响,而对Ⅱ、Ⅲ段没有影响。串补线路上区外故障时,保护Ⅰ段可能误动作,而区内故障时保护不会拒动作。在非串补线路上,若保护安装点到故障点的线路上有串补电容存在,保护可能会误动。次同步谐振对距离保护Ⅰ段的影响与串补度、故障点、故障类型和串补电容安装位置都有关。对保护安装处的电压、电流进行频谱分析表明,保护误动作本质上是由于电气量中含有次同步分量,造成测量阻抗发生了偏移。

By building simulation models based on actual parameters of the system,simulating and observing the measured impedance trajectory diagram,studies on the influence of subsynchronous resonance on distance protection are carried out in this paper. Simulation results show that the subsynchronous resonance has an influence on distance protection section Ⅰbut not on section Ⅱ and section Ⅲ.When there is outer fault in the series compensated line,section Ⅰ may be misoperated,while the line has internal fault,the protection will not refuse action. In the transmission line without series compensation,if the line,from protection installation point to the point of failure,has series compensation capacitor,section Ⅰ may be misoperated. Influence factors of the subsynchronous resonance on distance protection section Ⅰ include series compensation percentages,fault points,fault types and locations of series compensation capacitors.Spectrum analysis of the voltage and current at the protection installation point shows that the voltage and current contain subsynchronous harmonic components,resulting in the deviation of the measured impedance.