Transient Analysis of Symmetrical Three-Phase Sudden Short-Circuit at Stator-Winding Terminals of a Loaded Salient-Pole Synchronous Alternator

Only sudden short-circuits at the open-circuit stator terminals of synchronous alternators are analytically studied in monographic and periodical technical literature, even if they hardly ever occur in industrial practice. Hence, an analytical approach is developed in this paper for the transient response to a symmetrical three-phase sudden short-circuit occurring at stator-winding terminals of a stand-alone three-phase salient-pole synchronous alternator, which is initially operating under loaded steady-state conditions. Closed-form analytical expressions are derived for the transient time-functions of electrical current strengths in stator-phase winding, rotor field winding and rotor equivalent short-circuited damper windings, as well as of the resistant electromagnetic torque of the considered salient-pole synchronous alternator, during the three-phase sudden short-circuit process. The transient analysis is corroborated by meaningful case-study numerical results.