气隙偏心对汽轮发电机定转子振动特性的影响

分析了气隙偏心故障时汽轮发电机定转子径向振动特征。首先通过分析发电机气隙偏心时气隙磁场变化,计算得到气隙磁导和气隙磁密表达式,然后得到作用于转子的不平衡电磁力特性和作用于定子的脉振电磁力特性,最终得到定转子径向振动特征。对于转子,静偏心将激发转子2倍机械转频的振动;动偏心将激发转子与转子机械转频同频的振动。对于定子,静偏心将激发定子2倍机械转频的振动;动偏心或动静复合偏心将激发定子1倍、2倍、3倍、4倍机械转频的振动。并实测了SDF-9型故障模拟发电机静偏心时振动信号,与理论分析结果基本吻合。

Analysis on Vibration Characteristics of Generator with the Fault of Eccentric Air-Gap

The vibration characteristics of the generator's stator and rotor in the case of eccentric air-gap fault are investigated. The variations of magnetomotive force, magnetic permeability and magnetic flux density in eccentric air gap are calculated. The frequency characteristic of imbalance magnetic pull acting on rotor and that of pulsating magnetic pull acting on stator core are analysed. The radial vibration signature of the rotor due to eccentric air-gap fault is that the rotor will vibrate with the double rotating frequency under the static eccentric fault, and will vibrate with the fundamental rotating frequency under the dynamic eccentric fault. However, the radial vibration signature of the stator is that the stator will vibrate with the double rotating frequency under the static eccentric fault, and will vibrate with the fundamental, double, triple and four times rotating frequencies under the dynamic eccentric fault or composite eccentric fault. The vibration data measured from SDF-9 generator validate the correctness of the analysis presented.