TDR Measurement with Utility-pole-distance Resolution in Overhead Distribution System

Abstract

It is necessary to detect a fault point in overhead distribution system for failure restoration. To search the fault point effectively and precisely, we apply TDR (Time Domain Reflectometry) measurement with utility-pole-distance resolution. In this method, we inject a pulse wave into distribution lines and measure the reflection. In this paper, the authors confirm propagation characteristics of overhead distribution system and compare the measurement of the reflected wave with the simulation result. Through the experiments, the authors confirm an influence of parasitic capacitances in overhead distribution facilities such as a transformer and a switchgear. When distribution facility is not connected with distribution line, the reflected wave from every utility pole and the end terminal are observed; the reflected waves from every utility pole are caused by parasitic capacitors between the distribution lines and cross arms. When distribution facility such as a transformer and a switchgear is connected with distribution line, the reflected waves caused by these facilities are observed. As a result, we confirmed that parasitic capacitances of distribution facilities affect the propagation characteristics of distribution failure pulse wave. In addition, the authors developed a simulation tool to evaluate the propagation characteristics of the pulse wave in the overhead distribution system based on the result utilizing the test distribution system, and confirmed that the simulation results corresponded to the measurement results.