Dynamic Analysis Of Large Turbo-generator Rotor Eccentric Faults

Rotor eccentricity fault is one of the main problems on the running of largeturbo-generator. With the rotor eccentricity fault, the generator air gap becomesuneven and the air gap magnetic is changed. The electromagnetic force on the statorand rotor is uneven, and unbalanced magnetic pull will intensify rotor eccentric.Electromagnetic waves on stator and rotor core surfaces caused by the rotoreccentricity will generate mutations, and the stator and rotor vibrations are caused.Seriously the deformation of bearing and cracks of rotor also can be caused.A large turbo-generator is taken as the researched object. According to the rotoreccentricity fault, the2D and3D calculation models of generator are established.The no-load and load operation conditions of generator are simulated with thefield-circuit coupling method. The internal electromagnetic field distribution of themotor is calculated, and the effect on internal electromagnetic field distribution ofthe motor caused by rotor eccentricity fault is analysed. The harmonic analysis ofmagnetic flux density on rotor surface is carried out.Combining with Maxwell stress method, the electromagnetic waves on rotor andinner stator surface under different operation conditions are calculated while therotor is with radial eccentricity. The changes of radial and tangential electromagneticwaves on stator and rotor core surfaces are analysed when the rotor eccentricity faultoccurs. The influence of axial eccentricity to electromagnetic waves on rotorsurfaces of rotor eccentricity both sides is calculated. The influence of different axialeccentricity length to electromagnetic force peak on rotor surfaces of rotoreccentricity both sides is analysed.Using the analytical method, turbo generator air gap magnetic conductance andmagnetic flux density are analyzed on the normal operation, and the vibrationcharacteristics of stator and rotor are received. The air gap magnetic density and thechanges of electromagnetic force on stator and rotor surface are calculated whendifferent rotor eccentricity faults occur, and the vibration characteristics of stator and rotor are received. The vibration characteristics of stator before and after staticeccentricity are validated by the numerical calculation method.