Optimal Capacitor Placement on Three-Phase Primary Feeders: Load and Feeder Unbalance Effects

Generalized procedures are presented for optimizing the net dollar savings resulting from reduction of power losses through shunt capacitor placement on three-phase, four-wire, multi-grounded primary distribution feeders. These procedures are based on a voltage-dependent model which is developed from results of a three-phase a, b, c phase-frame of reference load flow. Power-invariant transformations are introduced to decouple the actual three separate phases and thereby yield three equivalent single phases with common definition of feeder length. The effects of ground-wire and earth-return paths for balanced and unbalanced system and load conditions are accommodated within the models presented.