暂态电流保护选择性的研究(Ⅰ)--故障暂态过程分析

针对保护出口处发生金属性或小电阻短路故障时，暂态电流保护完全失去选择性的严重缺陷，利用时域分析方法，进行了详细的故障暂态分析和仿真研究。研究结果表明，线路出口故障时暂态电流保护完全失去选择性的根本原因是，在给定的采样频率的限制下，难以捕捉到过渡过程中极其短暂的母线分布电容中的暂态电流，从而故障线路与非故障线路暂态电流波形的奇异性相近，根据故障线路和非故障线路的暂态保护判据计算结果不能正确识别故障线路。

Study on the Selectivity of the Transient Current Protection(Ⅰ)--Transient Analysis of Line Exit Fault

For the severe limitation that the selectivity of transient current protection will lose when the fault with small resistance or without resistance takes place at the end of transmission line,the basic reason for the selectivity loss of transient current protection was investigated. The transient analysis and simulation studies in time-domain showed that the transient capacitance current of busbar is unable to be caught due to the limitation of the given sampling frequency, therefore the transient current singularity of the fault line and the non-fault line will approximate, which prevents to identify the fault line with the criterion calculation result of transient current protection.