Power system state estimation using three-phase models

Phase imbalances can occur at both the distribution and transmission levels of an electric power system. It is shown that these imbalances can have a significant negative impact upon the performance of a state estimator which utilizes only a positive-sequence model of the power system. A state estimator which uses a full three-phase model of the system is developed and various transmission and distribution networks are simulated. Depending on the level of imbalances, the improvement in state accuracy can be dramatic. In addition, an explanation for large reactive power measurement errors is presented and empirically validated.>