Tracking State Estimation in Distribution Networks Using Distribution-level Synchrophasor Data

State estimation is often a challenging task in distribution systems due to numerous nodes and limited number of measurement sources. As a result, distribution system state estimation is often not real-time; instead, it is done once every 5 to 15 minutes, e.g., when smart meter measurements are available. Accordingly, this paper proposes a novel method for tracking state estimation in distribution systems to update the system states following an event, e.g., a sudden load change, that occurs in between the 5 to 15 minutes intervals of a typical distribution system state estimation cycle, without the need to rerun the whole state estimation. This method is of great interest for real-time monitoring and control applications. The proposed method uses measurements from as few as only two distribution-level phasor measurement units, a.k.a., micro-PMUs, that are installed at the substation and at the end of the main feeder or laterals. The method is developed based on the compensation theorem in circuit theory to generate an equivalent circuit according to the pre-event and post-event feeder data in order to update the state estimation results. The effectiveness of the proposed method is demonstrated through simulating the IEEE 33-bus test system.