水轮发电机转子系统碰摩弯扭耦合振动分析

机电耦联振荡诱发的水轮发电机转子、定子碰摩现象,会加剧转子系统的弯扭耦合振动,进而诱发机组系统严重的安全事故。建立水轮发电机转子系统定、转子碰摩运动微分方程,利用数值积分方法,研究了电磁刚度、转子质量偏心、阻尼及定子径向刚度等对转子系统非线性动力特性的影响。结果表明,弯曲和扭转电磁刚度对弯曲和扭转振动存在相互耦合激发放大作用,但随着偏心的增加,电磁刚度的影响程度减弱;质量偏心较大时弯扭耦合作用强烈,弯曲或扭转阻尼比的影响作用较大;定子径向刚度增大导致径向碰摩力增大,弯振幅值略有降低,扭振幅值增加,振动频率成分复杂。所得结论可为转子系统的设计、运行、振动控制预测及诊断提供参考。

Study on bending-torsional coupling vibrations of rub-impact rotor system for hydro turbine generators

Rub-impact between the stator and rotor of a hydro turbine generator caused by electromechanical coupling oscillations, could excite bending-torsional coupling vibrations and even lead to serious safety accidents. This study has developed a bending-torsional coupling dynamic model of the rub-impact rotor system and made an analysis of the coupling vibration behaviors using numerical method, focusing on the influence of electromagnetic stiffness, mass eccentricity, and damping ratio on the vibration signals in time and frequency domains. Results show that bending and torsional electromagnetic stiffness had a coupling effect that tended to excite and amplify the vibrations, but this effect decayed as the eccentricity was increasing. When mass eccentricity was large, damping ratio had an important role because of the strong effect of bending-torsional coupling. An increase in stator radial stiffness leaded to weaker bending vibrations but stronger torsional vibrations. The results would be useful to the design, control and diagnosis of rotor systems and their economical operation.