Dynamic behaviour of a four-poles turbo generator with rotor eccentricity

Smooth-poles generators of electrical power plants are flexible and this causes the eccentricity of the rotor with respect to the stator. The consequent air-gap asymmetrical distribution causes the phenomenon of the unbalanced magnetic pull (UMP). In this paper a non-linear model for the calculation of the UMP in synchronous electric machines is applied to a four-poles turbo-generator of 900 MVA, by taking into account not only the radial component of the electromagnetic stresses but also the tangential one