Modeling and Experimental Verification of Covered-Conductor for PD Detection in Overhead Distribution Networks

—Modeling Covered-Conductor Overhead Distribution Networks for PD Detection—

Abstract

Partial discharge (PD) measurements are universally accepted as an effective and reliable tool for on-line condition monitoring of high voltage equipments. A relatively new application is conducting on-line high frequency PD measurements to detect falling trees on covered-conductor (CC) overhead distribution lines. In this paper, theoretical model of CC overhead distribution line is presented and the frequency-dependent distributed transmission line (TL) parameters, wave propagation characteristics (attenuation, phase constant, and propagation velocity), and characteristic impedance are calculated. The derived wave propagation characteristics are compared with those obtained from the time domain reflectometry (TDR) measurements to validate the theoretical model of the CC line. An accurate determination of the TL characteristics for CC lines can be used as a design aid to develop PD measuring system for condition monitoring; thus deciding the optimal locations of the sensors in getting reliable PD detection results to detect falling trees on CC overhead distribution lines.