Improved Observability in Distribution Grids Using Correlational Measurements

This paper develops a novel pseudo-measurement construct termed a Correlational Measurement (CM) to improve observability and state estimation accuracy. CMs utilize the correlation between similar classes of loads and DERs. The modifications required to accommodate CMs in traditional node voltage or branch current based state estimators are derived. Additionally, an observability analysis framework for distribution systems with DERs is presented to seamlessly integrate CMs. The framework assembles an observability test and an observable island identification procedure from the literature along with a novel observability metric. Finally, an on-line CM parameter estimation procedure is presented. Simulations on the IEEE 123 bus test system and real field data from Pecan Street demonstrate the utility of the proposed CMs and the observability analysis framework in improving observability and state estimation accuracy.