On-line Estimation of Transmission Line Parameters Using Synchronized Measurements

A new on-line method for estimating transmission line constants of a power system is proposed in this article. The method applies a digital dynamic filter technique to perform the estimation based on minimization of residual least absolute value. The proposed technique can be used on-line to account for any dynamics changes in line constants. Synchronized phasor measurements are used to feed the dynamic filter. The synchronized samples of voltage and current waveforms, at both the receiving and sending end terminals, are used to set an over-determined system of equations. The problem is formulated as an estimation problem. Different practical case studies are presented. Eventually, the proposed discrete dynamic filtering algorithm estimates the ABCD constants and, consequently, the line parameters of both short and long lines. Effects of different factors, such as noise and unsynchronized samples, are studied. Results obtained show the reliability and accuracy of the method in estimating the transmission line parameters.