Estimation of transmission line parameters from measurements

This paper describes the method of estimating the transmission line parameters from voltage, current, and power measurements at the two ends of the line. This becomes necessary if a new parallel transmission line is constructed between two substations due to load growth or if an underground cable replaces an overhead line and the overall parameters of the paralleled lines or the cable are desired to be determined. The parameters of the equivalent pi network of the line are obtained from the measurements at the line ends by using the Newton–Raphson method to solve the non-linear equations. The proposed method then gives the resistance/m, inductance/m, and capacitance/m, considering the distributed nature of the transmission line. The technique to determine the conductance parameter is also presented.