Analysis of sudden unbalanced short circuits in synchronous machines by applying the principle of harmonic balance

Abstract

The fundamental idea of the principle of harmonic balance is introduced; the simplified flux-linkage and voltage equations of 3-phase synchronous machines were obtained by means of some necessary assumptions; then by applying the principle of harmonic balance, the sudden line-to-line unbalanced short circuit of 3-phase synchronous machines were analyzed concisely, the magnitudes of the odd and even harmonics of short-circuit currents and their time constants of decay were gained at the same time. The method can also be used in the analysis of unbalanced short circuits of 6-phase and other multiphase machines.