Compensation of Systematic Measurement Errors in a PMU-Based Monitoring System for Electric Distribution Grids

摘要

The availability of accurate measurements is the prerequisite for the actual implementation of many monitoring and management applications in smart distribution networks. 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 an accurate network monitoring. At the same time, the smartness of the grid can include the possibility for the measurement system to self-detect its weak points and improve its performance. In this perspective, a technique for the estimation and the compensation of systematic errors existing in the components of a PMU-based distributed measurement system suitable for monitoring three-phase distribution networks is presented. The uncertainty induced by the components of the measurement system, mainly instrument transformers and PMUs, is included in the model, along with the uncertainty affecting the values of the network line parameters. The method exploits the possible constraints introduced by the grid topology (presence of multiple lines, injected currents, etc.) to improve the accuracy of the estimation so that a proper compensation of the estimated errors can be allowed. The validity of the approach is verified though simulations performed on a small portion of a test medium voltage distribution grid.