基于测距函数相位特性的T型高压线路故障定位原理

A Novel Fault Location Algorithm Based on Phase Characteristics of Fault Location Function for Three-terminal Transmission Lines

针对现有T型高压线路故障测距方法在T节点附近高阻短路故障时有测距死区这一不足,提出一种适用于T型高压线路的故障快速定位法。通过分析可知,在故障支路故障点前后测距函数的相位会发生一次突变,在正常支路上测距函数的相位不会发生突变,因此可根据故障支路上测距函数的相位突变点即为故障点这一特征进行故障定位。该方法将故障支路判别和故障测距融为一体,无需事先判别故障支路即可测距。该方法无测距死区,较好地克服了传统方法在T节点附近有死区的不足。该方法对电弧故障具有良好的适用性。PSCAD/EMTDC仿真结果表明,该方法基本上不受过渡电阻、故障类型、故障位置和负荷电流等因素的影响,在各支路参数偏离设计值时依然能正确识别故障支路,保持较高的测距精度。

While the high resistance fault occurs near the teed node, the current fault location methods used for teed lines can’t identify the fault section correctly, thus fail to locate the fault. To overcome the defect, a new fault location algorithm based on the phase characteristics of fault location function is proposed. The fault location function is established on the basis of the concept that selects a reference point to match the fault. It is concluded that, the phase characteristics of the function in the fault branch is different from that in the healthy branches, and the phase of the function will have a step jump when the reference point changes from the left to the right of the fault in the fault branch. So the position in the fault branch where the fault location function has a step jump is the fault position. The method can locate the fault without identifying the fault section first, thus remedies the defect of traditional fault location methods in which dead zone of fault location exists. The accuracy of the proposed method is hardly affected by fault location, transition resistance, fault types and load current, and has less amount of calculation than the current fault location methods. The results of simulation by PSCAD /EMTDC show that the proposed algorithm is correct and can locate the faults accurately.