Power cable defect location method based on frequency domain reflectometry

• 1、State Key Laboratory of Power Transmission Equipment & System Security and New Technology,Chongqing University,Chongqing,400044

Abstract： The safe operation of a power grid requires quick and nondestructive location of defects in power cables before faults occur. Insulation aging and physical wear and tear may damage underground power cables, although defective cables can temporarily transport electricity, the inability to detect local insulation defects early on can result in serious power failure in the action of electric field.The method measures the reflection coefficient (S11) spectrum at one end of cables, and then the location of local defects of cable is obtained after Inverse Fast Fourier Transformation (IFFT). In this paper, first, the cable distribution parameter model is established, and the feasibility of using the S11 spectrum to locate local defects is proved in details. Then the simulation model of the local insulation defect is built. Location of different local defects caused by the variation of cable distribution parameters was carried out.This method is a non-destructive measurement method with high sensitivity, and the location process takes a short time. Simulation results show that the defect can be accurately located with a spatial resolution as short as 0.01m, even if the distribution capacitance only changes +2.5%.The method is of great significance for quickly and accurately detecting the power cable defect point and reducing the fault range.

Keywords： electrical theory and new technology cable defect reflection coefficient frequency domain reflectometry