PMU-Based State Estimation: A Multi-Snapshot Approach for Mitigating the Impact of Systematic Errors and Line Parameters Uncertainty

The widespread installation of phasor measurement units (PMUs) revolutionized transmission systems monitoring, providing timestamped measurement data to state estimation algorithms. In this respect, there are two key aspects that are often overlooked, even though they cap overall performance. Firstly, the knowledge of line parameters is typically subject to rough errors. Moreover, the most significant uncertainty contribution affecting phasor measurements is given by the systematic errors introduced by the instrument transformers. Both of these errors clearly exhibit strong time correlation. In this scenario, the present paper proposes a new multi-snapshot approach to state estimation that merges data collected in different time instants and enables improving accuracy by properly modeling the aforementioned correlations. The remarkable advantage of the method is demonstrated both analytically and through extensive numerical simulations carried out on the IEEE 14-bus test system and validated on other IEEE standard networks. A greedy procedure for retrieving the best subset of time instants to be combined is proposed and validated. Results highlight its effectiveness with respect to the exact solution, in spite of a high reduction in computational cost.