Analysis On Winding Electromagnetic Force Characteristics Under Air-gap Eccentricity And Interturn Short Circuit Compound Fault

In this paper,the research object is QFSN-600-2YHG type 600 MW turbo-generator.Rotor and stator winding electromagnetic force(EF)characteristics under normal condition,rotor winding interturn short circuit fault,air-gap static eccentric fault and their compound fault are studied with qualitative analysis and quantitative calculation.Firstly,the approximate calculation formulas of EF are derived according to air-gap magnetic flux density(MFD)under normal and fault conditions.Then finite element simulation software Ansoft is used to carry out numerical calculation.The two results are compared and the differences are analyzed.At the same time,the winding EF characteristics under fault conditons are compared with those under normal condition.The effects of faults on EFs are analyzed.This paper analyzed the amplitude,the effective value and the harmonic component etc.The research found that:1)Under normal condition,the EFs on rotor windings fluctuate slightly,and the harmonic components are 6k(k=1,2,3……)harmonic.The EFs on stator windings vary approximately like the cosine curve and the components of stator EFs are DC and even order frequency.2)Under rotor winding interturn short circuit fault,the EFs on fault windings usually reduce obviously and EFs on other normal rotor windings change a little.The odd order harmonic components of EFs appear on stator windings.3)Under air-gap static eccentricity fault,the fluctuation of rotor winding EFs increase obviously.Compared to normal condition,rotor winding EFs appear first harmonic,fifth harmonic and seventh harmonic etc.After the eccentric fault,the peak values of EF on different stator windings become much different.Some of them increase,and some of them decrease.4)The current research shows,under compound fault,the characteristics of EFs seem like the two single fault sets.In the case of compound fault,all the EF characteristics under the single fault are expressed.The achievements obtained in this thesis offer a theoretical reference for the winding insulation abrasion and protection under the single and the composite faults composed of air-gap eccentricity and rotor interturn short circuit.Meanwhile,they can be also used as the supplement of the fault identification of these generator faults.