Hydropower units are subject to several forces and couples, under certain conditions they can cause noise, vibration, and interaction problems with the electric network or even equipment failure. The objective is to develop numerical models of the hydroelectric generator taking into consideration the shaft interaction in order to study the behavior of the generator. An analytical method is implemented in order to study the interaction of the oscillation of the mechanical couple with the network, and its influence on the electromagnetic couple. A finite element model is developed in order to study the impact of eccentricity on the generator, which is the origin of unbalanced magnetic pulls. Depending on the degree of eccentricity, the resulting electromagnetic force can be significant. Finally, the aim of this work is to contribute to the study of the dynamic behavior of the shaft in hydropower units.