Techniques for the Steady State Representation of Unbalanced Power Systems: Part II. Simplification of System Model and Representation of Passive Control Devices

A power system model that accounts for mutual coupling effects, the effects of neutral and static conductors, and the finite conductivity of earth is generally large and explicitly represents many uninteresting currents and voltages. A systematic procedure is presented to greatly reduce the order of such a model without loss of information regarding suppressed variables. A convenient method is presented for representing the effects of passive control devices such as tap-changing-under-load transformers, and an example multiphase load flow solution is given for a small unbalanced power system.