POWER-SYSTEM STATE ESTIMATION USING 3-PHASE MODELS

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