On the Evaluation of Monitoring Systems for Distribution System State Estimation: Observability, Reliability, Estimation Accuracy

As renewable energy sources are integrated into distribution grids, efficient monitoring systems are needed to ensure efficient grid operation. This paper presents a comprehensive evaluation approach for distribution grid monitoring systems, focusing on observability, reliability, and estimation accuracy. Through a critical assessment of observability, it is demonstrated that the linearized Jacobian matrix can be effectively utilized for observability analysis in distribution grids. Building on this foundation, a method for approximating state estimation accuracy is developed, using the linearized Jacobian matrix to reduce computational effort. The accuracy is characterized by constructing confidence intervals derived from the covariance matrix. Two methods with varying levels of simplification provide qualitative or quantitative results, which can be used to design monitoring systems for distribution system state estimation.