Three-Phase Subharmonic Oscillations in Symmetrical Power Systems

Abstract

This work makes a three-phase TNA study of the most commonly observed subharmonic oscillation, that is, the 1/3-order subharmonic. Symmetrical Y-connected systems are studied wherein the neutral is firstly solidly-grounded, and secondly resistively-grounded. The influence on the subharmonic performance of this, and other system parameters, is determined. The belief that 1/3-order subharmonic oscillations could not occur in ungrounded symmetrical systems is shown to be incorrect.