灯泡贯流式水轮发电机组轴系非线性动力学特性研究

发布时间：2018-05-17 12:58

本文选题：水轮发电机 + 轴系　；参考：《东北大学》2014年硕士论文

【摘要】：水轮发电机是一类集机械、电磁和水力等因素相互影响、相互制约的复杂非线性动力系统,其机组轴系在运行过程中表现出复杂的非线性动力学特征。随着水轮发电机组功率和尺寸的急剧增大、比转速的提高,机组振动和稳定性问题也越来越突出,特别是在非线性油膜力、不平衡磁拉力和转定碰磨力的作用下,其动力学特性就会变得非常复杂,研究水轮发电机组振动的机理和规律,对于从根本上改善机组的动态特性有着极其重要的意义。本文的主要研究工作有：首先根据灯泡贯流式水轮发电机组轴系布置方式建立了双支点双悬臂的转子—轴承模型,在考虑到重力、浮力、水力不平衡力、非线性油膜力的情形下,推导出了水轮发电机不平衡转子系统振动的动力学微分方程。分析了转速、转子偏心距等参数对转子系统动力学特性的影响。研究发现,随着转速、转子偏心距等参数的变化,系统的非线性动力学特征变得十分复杂,出现了周期运动、倍周期分岔和混沌运动。其次,为了更为准确的把握转子—轴承系统在电磁故障下的动力学特征,本文建立了不平衡磁拉力作用下转子-轴承系统的非线性动力学模型。讨论了转子转速、励磁电流等参数对系统动力学特性的影响。结果表明,转子转速和励磁电流对转子系统的振动特性影响显著,随着转速的逐渐增大,转子的振动幅值先增大后减小；随着励磁电流的不断变化,系统由稳定的周期运动进入拟周期运动。最后,通过对轴向推力作用下的碰摩转子系统运动进行解析,建立了碰摩转子系统在轴向推力作用下的非线性动力学模型,详细分析了摩擦系数、定子径向刚度等参数对轴向推力作用下碰摩转子系统动力学特性的影响。分析发现,随着摩擦系数、定子径向刚度等参数的变化,碰摩力在转子系统运动中逐渐成为主导因素,系统表现出倍周期分岔、混沌运动等非线性动力学特征。本文通过对实际机组不同工况下的计算分析得出了机组随不同的控制参数变化时的动力学特性变化规律,为灯泡贯流式水轮发电机组的设计和稳定性分析提供了参考依据。
[Abstract]:Hydrogenerator is a kind of complex nonlinear dynamic system with mutual influence of mechanical, electromagnetic and hydraulic factors. Its shafting shows complex nonlinear dynamic characteristics during operation. With the rapid increase of power and size of hydro-generator sets and the increase of specific speed, the problems of vibration and stability become more and more prominent, especially under the action of nonlinear oil film force, unbalanced magnetic pull force and rotating impact force. Its dynamic characteristics will become very complicated. It is of great significance to study the mechanism and law of turbine generator unit vibration to improve the dynamic characteristics of the unit fundamentally. The main research work of this paper is as follows: firstly, the rotor bearing model of double fulcrum and double cantilever is established according to the shafting arrangement of bulb tubular turbine generator set, which takes gravity, buoyancy, hydraulic imbalance into account. In the case of nonlinear oil film force, the dynamic differential equation of the vibration of an unbalanced rotor system of a hydrogenerator is derived. The effects of rotor speed and rotor eccentricity on the dynamic characteristics of rotor system are analyzed. It is found that with the change of rotational speed and rotor eccentricity, the nonlinear dynamic characteristics of the system become very complex, with periodic motion, period doubling bifurcation and chaotic motion. Secondly, in order to more accurately grasp the dynamic characteristics of rotor-bearing system under electromagnetic fault, the nonlinear dynamic model of rotor-bearing system under unbalanced magnetic pull is established in this paper. The effects of rotor speed, excitation current and other parameters on the dynamic characteristics of the system are discussed. The results show that the rotor speed and excitation current have a significant effect on the vibration characteristics of the rotor system. With the increasing of the rotor speed, the vibration amplitude of the rotor increases first and then decreases, and with the constant change of the excitation current, The system changes from stable periodic motion to quasi periodic motion. Finally, by analyzing the motion of rub-impact rotor system under axial thrust, the nonlinear dynamic model of rub-impact rotor system under axial thrust is established, and the friction coefficient is analyzed in detail. The influence of stator radial stiffness and other parameters on the dynamic characteristics of rub-impact rotor system under axial thrust. It is found that with the variation of friction coefficient, radial stiffness of stator and other parameters, rub-impact force gradually becomes the dominant factor in rotor system motion, and the system exhibits nonlinear dynamic characteristics such as periodic doubling bifurcation, chaotic motion and so on. Based on the calculation and analysis of actual units under different working conditions, the dynamic characteristics of units with different control parameters are obtained, which provides a reference for the design and stability analysis of bulb tubular turbine generator sets.
【学位授予单位】：东北大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM312

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