Utilization of PMU Measurements for Three-Phase Line Parameter Estimation in Power Systems

A new method is developed for synchrophasor-based estimation of three-phase transmission line (TL) impedance parameters, applicable for both fully transposed and untransposed TLs. The method is based on accurate time-synchronized measurements of the voltage and current phasors at both ends of a TL. The method estimates the line impedance values using a robust estimator with the property that the influence of outliers on the final results is minimized. A robust estimator is chosen as an alternative to well-known ordinary least-squares estimators which are highly sensitive to outliers. The performance of the method has been evaluated using a laboratory setup simulating real power system conditions. The necessary conditions for algorithm convergence as well as the requirements for measurement accuracy have been studied. In addition, this paper describes validation results of the proposed method in real high-voltage power system conditions by measuring voltage and current phasors with two phasor measurement units installed on both terminals of a 400-kV fully transposed overhead TL.