Analysis of Hybrid State Estimators: Accuracy and Convergence of Estimator Formulations

This paper provides a comprehensive analysis of several hybrid state estimators (HSEs) to assess their performance and identify their unique characteristics in transmission network. The results reveal that the formulation of an HSE can have a significant impact on both the estimation accuracy and the convergence properties of the estimator, which are the two most important performance factors for an HSE. Furthermore, the analysis performed has identified the formulation that maximizes these factors. The assessment can be divided into three parts. The first part conducts comprehensive simulations for the IEEE 14 bus test system for every possible phasor measurement units (PMU) placement. The second part validates the conclusions made in the first part using simulations of the IEEE 118 bus test system with both random PMU placements and optimally and suboptimally selected placements. The third part further validates these conclusions and directly explains the reasons for the differences in estimation accuracy observed for the different formulations of HSEs through mathematical analysis.