microprocessor based measurement of π-model transmission line parameters under fault conditions

This paper presents design, development and testing of an Intel-8086 microprocessor based system for the measurement of transmission line parameters (R and X) under fault conditions. The value of R and X from relay location to fault point are required to be known in order to determine whether the fault point lies in the relay´s protective zone or not. In differential equation solution based on series R-L transmission line model, shunt capacitive effect is ignored. Obviously, algorithm is not accurate particularly for medium and long transmission line protective relaying design. Therefore, it is necessary to measure and consider the shunt capacitance of transmission line. The algorithm used for the measurement of transmission line parameters is based on the solution of differential equation using pi-model transmission line.