高压电缆护层交叉互联时的行波故障测距

为研究采用三相护层交叉互联方式的高压电缆线路的行波测距方法,讨论了裸露高压电缆(电缆沟或隧道敷设)的相量参数和模量参数的计算方法。通过分析模量参数的特征,将电缆中的模量分为内模量和外模量,分别计算了直埋电缆和裸露电缆的内、外模量波速,计算表明裸露电缆的外模量波速高于内模量。电缆护层交叉互联时,内、外模量会因行波折反射而相互转化,波速较快的外模量会对内模量波头造成干扰,给裸露电缆的双端行波测距造成影响。理论分析和数值计算表明,采用三相芯线电流之和作为行波测距信号,可有效消除外模量干扰,大大加强内模量波头特征,有利于提高行波测距准确度。

Traveling Wave Fault Location for Crossbonded HV Cables

To develop a traveling wave fault location method for crossbonded cables,which might be buried underground or naked outside,the paper presents a method to calculate the phase and modal transform of naked High Voltage(HV) cables,which are laid in tunnel or ditch.Based on the characteristic of modal parameter,the modulus are classified as inner modulus and outer modulus.Wave velocities of both directly-buried cables and naked cables are calculated,and results show that the outer modulus waves travel has higher velocity than the inner modulus waves in the case of naked cables.If the cable sheaths are crossbonded,then the inner modulus and outer modulus will be reflected and refracted to each other at the crossbonding point.For naked and crossbonded cables,the outer modulus waves will make distortion to the inner modulus wave-front and add trouble to fault location.It is suggested that using the sum of three core currents as fault location signal can eliminate the distortion efficiently and reinforce the wave characteristic greatly.With this method,the fault location accuracy is highly improved.