A Novel Approach to Noninvasive Measurement of Overhead Line Impedance Parameters

Transmission line impedance parameter estimation forms an essential part in modeling and monitoring of electricity networks. The accuracy of the estimated parameters has a direct impact on various functions of network operation, such as state estimation, fault location, and dynamic thermal line rating. Impedance parameters can be estimated from voltage and current measurements taken at the ends of the transmission line. Previous research has produced a range of methods with the purpose of maximizing the accuracy of the estimated values. However, the input measurements from the line ends can contain systematic errors that are introduced by the instrumentation channel and significantly reduce impedance parameter accuracy, which is not taken into account by most of the existing methods. In this paper, a novel method is presented that estimates correction factors for the systematic errors and, thus, increases the accuracy of impedance parameter values. The performance of the new method is compared with an existing one in a case study on laboratory measurements.