Mechanical Response Before and After Rotor Inter-turn Short-circuit Fault on Stator Windings in Synchronous Generator

This paper studies on the stator winding electromagnetic force (EF) and mechanical response under rotor interturn short circuit (RISC) fault in synchronous generators. Taking the phase A of stator winding in MJF-30-6 type fault simulating generator as studying object, Firstly, qualitative formulas of the EF before and after RISC are obtained to show the impact of RISC on the harmonic component changes caused by the fault, respectively. Then, 3D finite element calculations are taken to obtain the quantitative EF data for the windings. Finally, solution results based on EF properties, mechanical response before and after RISC on stator winding can be substantiated. It shows that the occurrence of RISC will bring in extra odd harmonics to the EF. Moreover, as RISC takes place, the DC component and (4m-2)-th harmonics (2nd) of the EF will be decreased, while the amplitude of the odd harmonics (1st, 3rd) will be increased. What's more, No matter in normal condition or under RISC, the nose-top, the middle of the involute part, and the connection district between the end winding and the line winding, are the three dangerous positions where the insulation may damaged after a long performance and therefore need special manufacturing and monitoring attention.