Fault Characteristic Study Based on FLUX 2D for Large Synchronous Generators With Stator Winding Inter-turn Short Circuits Under Rated Operating Conditions

This paper investigates the stator winding short circuit characteristics in synchronous generators under rated operating conditions by combing the single-winding analytical method and the finite element method(FEM),which is still the effective method to determine currents and torques under specific fault conditions.Some special measures have to be considered in case of the electromagnetic transient process under the condition of inner faults,e.g.,the correct interconnection between sub-strands and the grid is of the particular importance for inner fault simulations.The previous results show that the traditional calculation method based on the equivalent networks fails in case of the inner asymmetry magnetic field.Based on the systematic investigation of a turbo generator with inter-turn short circuits,the results of this paper show the short circuit currents,phase currents,torques and the radial forces have strong correlations with the location and the turn number of faults.In some cases of inter-turn short circuits,the fault currents exceed that of the outer faults.Furthermore,strong radial forces acting on the magnet wheel might lead to the damages of the total shaft train.