基于光学电流互感器的非周期分量线路纵差保护

Study on Line Aperiodic Component Current Comparison Pilot Protection Based on Optical Current Transducers

采用输电线路分布参数模型,用拉氏变换法推导了高压、长距离输电线路故障时两侧的暂态非周期分量,研究结果表明,线路两侧的非周期分量在区内故障时表现为故障电流,区外故障时为穿越性电流,经过计算、比较,可准确判断区内、外故障。基于光学电流互感器能够准确测量非周期分量,提出一种新的线路非周期分量纵差保护原理,并给出动作判据。仿真结果表明,该原理保护不受故障类型、故障位置和故障过渡电阻的影响,基本不受线路对地分布电容影响,解决了传统工频量线路纵差保护因受线路对地分布电容电流影响而性能降低的难题。

Using Laplace transform calculates the transient non-periodic currents at two ends of HV long transmission line under distributed parameter model. Analysis indicate that non-periodic currents at two ends, which behave as fault currents in line internal fault whereas traversing currents in line external fault, could distinguish line external fault from internal fault via calculating and comparing. Based on optical current transformer, which can measure non-periodic currents accurately, a novel line non-periodic current differential protection is presented with its criterion. Simulation shows that its performance is free from the influences of various fault types, fault positions and fault path resistance, and it is basically not affected by the line distributed capacitor to ground, which can solve the puzzle of the traditional line fundamental current differential protection＇s performance degradation due to the line distributed capacitive current to ground.