Modeling Unbalanced Power Systems for Supervisory Monitoring and Control

A technique for modeling passive control devices in unbalanced power systems for application to supervisory monitoring and control is described. The methodology is based upon a linear graph theoretic development of a multiport model for an unbalanced power system. The capability for dynamic updating of the model to account for the quasi-steady-state behavior of passive control devices is provided. A power flow solution is presented for a system containing both topological and load imbalance. The solution is based upon an admittance model which uses phase coordinates to account for both unbalanced component configurations and passive control devices. The solution yields control device tap settings and port voltages that are calculated with respect to their particular voltage reference. This technique gives an accurate multiphase model usable for distribution system automation applications.