Impact of Simplified Models on the Accuracy of Transmission System State Estimation

The classical formulation of the transmission system state estimation process assumes balanced loads, symmetric networks, and measurements with independent random errors. As a result, most State Estimators (SEs) found in the literature utilize a single-phase model along with a diagonal weighting matrix. However, if at least one of these hypotheses is false, the results of these SEs are compromised. This paper examines the effects of asymmetric networks, unbalanced loads, and measurement dependency on the accuracy of SEs when applied to Transmission Systems (TSs). The investigation considers a real Brazilian TS and three different SEs. Each is based on different hypotheses about network characteristics and the statistical properties of measurement errors. Several simulation results have demonstrated the significant impact of asymmetric networks, unbalanced loads, and measurement dependency on the accuracy of SEs when applied to TSs.