| Rotor eccentricity is one of the main faults of large turbo-generator. In this state, themagnetic field distribution of the gap and core may be changed, the vibration of statorand rotor will be exacerbated, as well as the core deformation, winding wear anddielectric breakdown will be caused.A large turbo-generator is taken as the research object in this paper. Firstly, the2-Dfinite element model of turbo-generator under different working conditions withdifferent eccentricity is established on the basis of motor finite element analysiscombined with classical electromagnetic theory. Influence of rotor eccentricity onno-load and rated excitation current is calculated and analysed.Secondly, the air gap flux density distribution of generator rotor in two kinds ofconditions with different eccentricity is calculated. Changes of air gap flux densityharmonic, which has been decomposed are analysed, and the distribution ofcorresponding waveform is obtained. Magnetic field distribution of the tooth and yokeof stator and rotor, as well as the influence and laws of rotor eccentricity on flux densitydistribution in different locations of generators is qualitative and quantitative analysed.And on this basis, the iron loss of stator tooth and yoke before and after the eccentricityis calculated.Finally, unilateral magnetic force between stator and rotor of turbo-generator afterrotor eccentricity and the influence of rotor eccentricity on electromagnetic force ofwindings is studied and calculated using principle of virtual displacement combined withfinite element method on the basis of the generator magnetic field distribution.Inaddition, the electromagnetic force distribution of stator and rotor windings before andafter the eccentricity is obtained. The research conclusions obtained in this paper are fullof theory reference value and active meaning for the diagnosis of the eccentric fault and the analysis of fault development trend. |
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