适用于串联电容补偿线路的距离保护新原理

Research on New Principle of Distance Protection Adapted to Series Capacitor Compensated Line

以串补电容安装于线路末端的运行方式为例,定义保护与串补电容之间的线路末端的计算电压为补偿电压,分别分析了在串补电容前和串补电容后故障时补偿电压的不同特征。在串补电容前故障时,补偿电压和保护安装处的电压反向,在串补电容后故障时,补偿电压和保护安装处的电压相位接近。据此提出了串联电容补偿线路故障点位置识别的方法,配合传统的距离保护形成新的适用于串联电容补偿线路的距离保护新原理。串补电容前故障距离保护动作情况完全由阻抗继电器决定,无需考虑串补电容影响。新原理能可靠防止距离保护的超越问题,且灵敏度基本不受串补电容的影响。EMTP仿真验证了新原理的有效性和可靠性。

Focusing on the operating mode of series compensation capacitors being at the end of transmission lines, this paper defines the terminal calculating voltage between the location of the protective relay and the series compensation capacitor as the compensation voltage. Then the characteristics of the compensation voltage are analyzed in the events of the fault location is before and behind the series compensation capacitor respectively. When the fault location is before the series capacitor, the phase of the compensation voltage is opposite to the voltage at the relay location; when the fault location is behind the series capacitor, the phase of the compensation voltage is close to the voltage at the relay location. According to the above results, a new method for fault location identification is put forward. Cooperating with traditional distance protection principle, a novel distance protection principle which is adapted to series capacitor compensated line is proposed. When the fault location is before the series capacitor, the distance protection operation is only decided by the characteristics of the impedance relay, immune to the effects of the series capacitor. This new principle can effectively avoid the overreach problem of distance relays and its sensitivity is generally not affected by series compensated capacitors. The validity and reliability of this principle is verified by Electro-Magnetic Transient Program （EMTP）.