PMU-based Technique for the Estimation of Line Parameters in Three-phase Electric Distribution Grids

Line parameters are the foundation of an electric network model, which is the basis for many monitoring and management applications. Improving the knowledge of these parameters can allow better performance of state estimation and protection measures, among other applications. Phasor Measurement Units (PMUs) can provide synchronized voltage and current measurements, referred to a common time reference (usually the Coordinated Universal Time, UTC). This feature, as well as the high accuracy and reporting rate of PMUs, can be exploited for the evaluation of line parameters of the monitored network. In this paper, a PMU-based algorithm, designed for the estimation of line parameters in a three-phase distribution network, is presented. The estimated parameters include the resistances and reactances in the phase impedance matrix of each three-phase line. The uncertainty induced by the components of the measurement system, mainly instrument transformers and PMUs, is included in the model. The algorithm allows for performing estimations either on a single branch or on a set of branches of the network, using time-aligned and coordinated measurements to improve the estimation accuracy. The validity of the approach is verified though simulations performed on a small portion of a test medium voltage distribution grid.