Use of a finite element model for the determination of damping and synchronizing torques of hydroelectric generators

Damping and synchronizing torque coefficients are calculated from time-stepped finite element simulations of a hydroelectric generator connected to an infinite busbar. The calculated torque coefficients are compared to those obtained from two-axis equivalent circuit simulations as well as classical analytical expressions. The influence of the damper winding type, and the size and nature of the system disturbance on the damping and synchronizing torques is explored. It is found that a finite element model of a hydroelectric generator typically exhibits both higher damping and synchronizing properties compared to a two-axis circuit equivalent of the same unit. In particular, the damping and synchronizing contributions from a continuous damper winding are substantially higher in the finite element model than in the equivalent circuit model. Moreover, explicit consideration of dynamic iron losses is found to not affect the damping and synchronizing torques predicted by the finite element model.

► Electromechanical oscillations (hunting) studied with finite element model.
► Damping and synchronizing torque coefficients determined from transient responses.
► Investigation of the effect of the damper winding configuration (closed or open).