Comparison of the hydrogenerator behavior during a field short-circuit in case with and without PI-controller using FEM

In this paper an investigation of the synchronous machine behavior during a field short-circuit as the generator is connected to the 50 Hz grid is presented. The behavior analysis has been carried out using the Finite Element Method (FEM) for two cases. In the first one the rotor speed is held constant and equal to the synchronous one, while in the second case the rotor speed is controlled by a PI-controller that modifies the applied torque of the rotor shaft. Throughout this operation all the machine currents (stator, rotor and damper), the electromagnetic torque and the rotor speed are investigated and analyzed.