A method of measuring three phase transmission line parameters for relay settings

Abstract

The purpose of this study is to develop a method to measure transmission line parameters for protection relay setting. For relaying schemes such as distance relays, current differential relays and fault locators, it is very useful to ascertain the precise setting values in service, without the need for setting calculations prior to installation, and also for the relays to be able to adaptively change their settings as the system configuration changes. This paper describes a method of untransposed live line measurement of the parameters of a three phase transmission line. We propose a mathematical approach using synchronous voltages and line currents at both ends of the line in different states, where two models, the equivalent PI circuit and distributed constant circuit, are employed. The efficiency and issues are shown using several simulation examples in MATLAB.