A state estimation algorithm for monitoring topology changes in distribution systems

This paper proposes a state estimation algorithm for the monitoring of topological changes in distribution networks, using real measurements at substations, pseudo measurements at load and distributed generation buses, and zero injections at transition buses. This is accomplished by a generalized state estimation formulation, based on a weighted least squares approach with equality constraints, which involves both real and pseudo analog measurements and operational constraints for the switching devices. Estimates of state variables and switching device statuses are simultaneously provided. The normalized residual test is used to effectively identify gross errors in analog and topological data. The network splitting problem, caused by switching operations, is also investigated by introducing appropriate pseudo measurements. An advantage over previous methods is that the proposed approach eliminates the need of repeated state estimation runs for alternative hypothesis evaluation. A 17-bus distribution network is employed to demonstrate its effectiveness.