Distribution System State Estimation Algorithm with Improved Angular Reference Treatment

The efforts to build smarter grids with automatic control and intelligent functionalities for Distribution Systems (DSs) rely upon correctly determining the operational condition of these circuits, which is the purpose of a State Estimator (SE). DSs are complex and unbalanced networks, and in the last years several studies have evaluated the use of SEs in DSs. Despite some good theoretical results, one incorrect assumption is usually made: considering the Reference Bus (RB) to have balanced voltage phase angles. This paper proposes a three-phase state estimation algorithm that enables a correct treatment of the RB, which allows the determination of the unbalance at this bus as part of its iterative process, without relying on Phasor Measurement Units or external information that can be imprecise. Simulation results on IEEE 34 and 123 bus test feeders show the feasibility of the algorithm and the effects of the RB’s mistreatment on the SE accuracy. •The proposed method provides the correct treatment of the reference bus in Distribution System State Estimation.•The algorithm enables to capture the voltage unbalance at the network correctly.•Identifying the number of references needed for three-phase state estimation through observability analysis.•Three-phase modelling for Distribution System State Estimation.