Use of phasor measurements and tuned weights for unbalanced system state estimation

Most energy management system applications are based on the positive sequence network model. Since most systems do not operate under fully-balanced operating conditions, methods to minimize the impact of the balanced operation assumption on the network applications must be developed. This paper studies the impact of load imbalances on state estimation results by comparing state estimates using different measurement assumptions. In particular, the use of PMUs and systematic tuning of measurement weights are studied as practical ways of addressing this issue. Several scenarios are simulated using IEEE test systems with different measurement configurations and performance improvement of the state estimator in response to the proposed changes is illustrated by simulations.