A Comparison of State Estimation Based External Network Modeling Methods

Real time external network modeling for online security analysis is a major issue in today´s interconnected power system. In this paper, a comparison of two different methods: one pass state estimation method and two pass state estimation method, for real time external network modeling are presented. The contamination of the internal system state due to the external network model is compared for the two methods. A set of significant external branch measurements are identified based on their sensitivities on the tie-line power flows. Those external measurements are updated in real time. Both the methods are implemented on the IEEE 118-bus system. The results indicate that the two pass state estimation method has a lesser impact of the external network model on the internal system state