Analysis of Damper Transient Currents in Salient-Pole Synchronous Generator With Skewed Armature Slots Considering Interbar Currents

Salient-pole synchronous generators with skewed armature slots have damper interbar currents that flow transversely between the damper bars through the core. The pattern of interbar and damper bar currents under disturbances is useful information to designers for comprehensive knowledge of damper's electromagnetic performances and potential improvement of design. This paper presents the measurement of the interbar and interpole resistances and develops the multislice two-dimensional (2-D) finite-element model with integrated interbar circuit for a 10-kW model generator. The damper currents of the generator under 3-phase sudden short circuit are calculated with this model and compared with the measured results for validation. The influences of the variation in skew and bar-iron contact resistance on the pattern of interbar and damper bar transient currents are investigated by calculations for the fault of 3-phase sudden short circuit. The calculated results show that small bar-iron contact resistances may result in axially uneven distribution of damper bar transient currents, and the magnitude of slot ripple in the interbar current at different axial positions vary with the skew in different manners.