一种电压互感器断线新判据

牵引变压器低压侧采用单相电压互感器,现有的判据无法准确识别电压互感器的断线故障。针对电压互感器断线会导致变压器低压启动过电流保护误动,提出一种新的电压互感器断线判据。利用两个不同时刻的电压和电流值可以计算出系统的等效阻抗,通过对比计算阻抗与实际阻抗可以检测出电压互感器是否发生断线故障。利用Matlab软件以成渝线石板滩变电所为例进行仿真,在断线故障、负荷变化、系统阻抗变化、对侧故障等情况下的仿真结果表明,新判据可以准确、快速地检测出电压互感器断线故障。

A Novel Method to Detect the Break Line of Voltage Transformer

The single-phase voltage transformer is used in the low-voltage side of traction transformer.The existing method can't detect the break line fault of voltage transformer correctly.In view of that the break line fault may cause the overcurrent protection with low-voltage enabled to misoperation,one novel method to detect break line of voltage transformer is proposed.With the voltages and currents at two different times,the system equivalent impedance can be calculated.By comparing the calculated impedance with the actual impedance,the break line fault can be detected.Matlab is used to simulate the Shibantan substation in Chengdu-Chongqing railway line.The simulated results in many operation states,including break line fault,load swing,system impedance swing and contralateral fault,indicate that the method can detect the break line fault of voltage transformer rightly and rapidly.