Prediction of rotor dynamic behavior of synchronous generators

Abstract

Synchronous generators form the main part of a turbo generator set, yet their rotor dynamic behavior is not as common as the turbines in the system. This paper addresses the rotor dynamics of synchronous generators. The generator is modeled as a beam for the shaft and rotor core, as lumped masses and transverse inertias for flywheels, fan, and exciter. Bearing oil film is modeled using speed dependent stiffness and damping coefficients in both direct and cross-coupled directions. Direct stiffness coefficients are modeled for the bearing housing and supporting structure. The unbalance response is also determined as a function of the speed. The analysis is repeated replacing the beam model of the shaft as a solid model.