Calculations on voltage unbalance for 3-phase synchronous systems

THE steady-state behavior in regulated systems which become unbalanced has been treated in an earlier paper.1 The treatment there was concerned principally with fault-type unbalances, though general unbalance was considered and amplified with an example. A need was felt for an extension in the direction of further quantitative evaluation of the degree of unbalance in voltage experienced as a function of load impedance unbalance in typical synchronous systems. The fact that in smaller systems the infinite bus concept no longer is tenable also calls for a simultaneous consideration of generator and load in affecting the final net bus line voltages. The work described here is a step in that direction, taking up general unbalance in wye-wye neutral-connected systems with illustrations for typical load conditions.