Performance of Three-Phase WLS Distribution System State Estimation Approaches

The roadmap towards the so-called Smart Grids calls for a clever and efficient management of the distribution systems. In this context, Distribution System State Estimation (DSSE) tools play a crucial role to acquire the knowledge about the effective operating conditions of the network and to enable the proper management and control functions operation. DSSE is usually performed by relying on a Weighted Least Squares (WLS) method. Different WLS formulations can be designed depending on the state variables used in the estimator. In this paper, an analysis concerning the two main classes of WLS approaches proposed for distribution systems is presented. Three-phase estimators with state variables based on both node voltages and branch currents have been considered. The performances in terms of accuracy, efficiency and numerical properties are analyzed and discussed. Results obtained on the 123 IEEE distribution network are presented and discussed.