Identifying the unknown circuit breaker statuses in power networks

Abstract

This paper describes an approach by which the circuit breaker status errors can be detected and identified in the presence of analog measurement errors. This is accomplished by using the least absolute value (LAV) state estimation method and applying the previously suggested two stage estimation approach by A. Monticelli (see ibid., vol.8, no.3, p.1143-9, 1993). The ability of the LAV estimators to reject inconsistent measurements, is exploited in order to differentiate between circuit breaker status and analog measurement errors. The first stage of estimation uses a bus level network model as in conventional LAV estimators. Results of stage 1 are used to draw a set of suspect buses whose substation configurations may be erroneous. In the second stage, the identified buses are modeled in detail using the bus sections and the circuit breaker models while keeping the bus level network models for the rest of the system. The LAV estimation is repealed for the expanded system model and any remaining significant normalized residuals are flagged as bad analog measurements, while the correct topology is determined based on the estimated flows through the modeled circuit breakers in the substations. The proposed approach is implemented and tested. Simulation results for cases involving circuit breaker status and/or analog measurement errors are provided.