Interturn Stator Faults Analysis of a 200-MVA Hydrogenerator During Transient Operation Using FEM

This paper presents an investigation of the behavior of a 200-MVA-synchronous hydrogenerator during interturn stator faults, focusing on the affection to the electromagnetic magnitudes, such as the currents and the electromagnetic torque. Two kinds of interturn fault are examined 1) a short circuit between two conductors belonging to the same phase; and 2) a short circuit between two conductors belonging to different phases. These faults have been investigated via simulation using the finite element method. The benefit of this method is that it gives the possibility to calculate, except from the classical electrical magnitudes (e.g., the stator and field currents, the load angle, and the electromagnetic torque), other magnitudes which in general are difficult to compute during transient operation (e.g., the damper currents and the electromagnetic field inside the machine air gap). The main aim of this paper is to highlight quantitative and qualitative the condition in the interior of the machine in the cases of typical faults, which usually can occur during the machine operation. So, it is possible to find out that faults exist in the machine through the measurement of the field and the stator currents.