水轮发电机组轴系非线性动力特性分析

发布时间：2018-03-19 20:43

本文选题：水轮发电机组　切入点：振动　出处：《大连理工大学》2014年博士论文　论文类型：学位论文

【摘要】：随着社会与经济的迅猛发展,水轮发电机组正朝着大型化、高速化和大功率方向发展,集成化程度越来越高。随着水电在电力能源结构中比例不断增加,其对电网稳定运行所带来的影响也逐渐加大。在水力、机械和电磁等外界因素的相互影响下,机组振动问题日益突出,由此引发的非线性动力学现象广受工程界和学术界关注,已成为水电行业的热点研究之一。本文以水轮发电机组轴系为研究对象,考虑到振动问题在机组运行过程中的普遍性,对转子-轴承系统在不平衡磁拉力作用下的动力特性、电磁力与密封力联合作用下系统的非线性动力学行为、水轮机转轮-密封系统的稳定性和由不平衡磁拉力(Unbalanced Magnetic Pull, UMP)引起的机组定、转子碰摩动力学特性等进行了系统的分析,论文主要研究内容和成果如下： (1)针对以往多从单一方面分析UMP或密封力激励下机组运动特性的问题,建立了考虑UMP和非线性密封力共同作用的机组转子-转轮-密封系统模型。该力学模型较好地反映了系统的非线性动力学行为,通过参数的敏感性分析可以进一步揭示其非线性失稳的产生和发展变化规律,为机组动力设计和运行稳定控制提供理论支撑。 (2)建立了机组转子-轴承系统的非线性电磁动力学模型和运动微分方程,从转子轴心轨迹和频域两方面,重点分析了轴承参数,如轴承长径比和轴颈间隙在有无UMP情况下对系统横向振动特性的影响,为机组振动故障诊断以及在UMP作用下的动力特性分析提供了参考。 (3)针对定、转子在UMP作用下的碰摩问题,首次建立了UMP作用下水轮发电机组碰摩转子-轴承系统的非线性动力学模型,并以与UMP大小关系最为紧密的参数之一一励磁电流作为重点分析对象,研究了其变化对系统动态特性的影响。该模型可以较好地反映碰摩转子系统在励磁电流变化过程中所呈现的一系列非线性动力学行为,能够解释系统在UMP与碰摩力耦合作用下的振动现象及其发生发展规律,为提高机组振动故障诊断的准确性与振动主动控制提供了有益借鉴。 (4)在对转子-转轮-密封系统动力特性分析的基础上,研究了水轮机转轮-密封系统在线性、非线性密封力作用下的稳定性及失稳临界转速。根据不同密封参数对失稳临界转速的影响规律,给出了系统减小、甚至避免自激振动的路线或措施,为机组转轮-密封系统的动态设计和稳定运行提供了参考。
[Abstract]:With the rapid development of society and economy, hydro generating unit is facing the large scale, high speed and high power direction, the integrated degree is higher and higher. With the hydropower in power energy structure in the proportion is increasing, its influence on the stable operation of the power grid is gradually increasing. In the interaction of mechanical and hydraulic. Electromagnetic and other external factors, unit vibration problems have become increasingly prominent, nonlinear dynamical phenomena caused by the wide attention of engineering and academic circles, has become a hotspot in the hydropower industry. Based on the shafting of hydraulic turbine generator unit as the research object, considering the universality of the vibration in the operation of the unit in the process of rotor bearing the system under unbalanced dynamic characteristics caused by magnetic force, the electromagnetic force and the sealing force combined effect of nonlinear dynamic behavior of the system, the turbine runner sealing system stability and not by The dynamic characteristics of stator and rotor rubbing caused by balancing Unbalanced Magnetic Pull (UMP) are systematically analyzed. The main contents and achievements of the paper are as follows:
(1) according to the previous analysis from a single UMP or motion unit sealing under the excitation problem, a system model is established considering the rotor - and UMP nonlinear seal force interaction of the runner - seal. The mechanical model can reflect the nonlinear dynamical system, through the sensitivity analysis of parameters can be further revealed the nonlinear loss produced steady variation and development, for the design and operation of power stability control to provide theoretical support.
(2) to establish the nonlinear electromagnetic dynamics model and differential equation of motion of rotor - bearing system, from the two aspects of the rotor axis locus and frequency domain, focuses on the analysis of the bearing parameters, such as length to diameter ratio of bearing and shaft in the gap has no effect on the transverse vibration characteristics of the system UMP, which provides a reference for the vibration fault the diagnostic unit as well as in the UMP under the action of dynamic analysis.
(3) for a given rotor under the action of UMP, rubbing, first established a nonlinear dynamic model of UMP under the action of turbogenerator rubbing rotor bearing system, and the parameters of one of the most closely to the excitation current and UMP size relations as the key analysis object, to study the effects of the change of dynamic the characteristics of the system. The model can reflect the rotor system appears in the excitation current changes in the process of a series of nonlinear dynamical behavior, can explain the system in the UMP and rubbing force under vibration and its occurrence and development regularity, provide a useful reference for active control to improve the accuracy and vibration fault diagnosis the unit.
(4) based on the analysis of the dynamic characteristics of the rotor system - wheel - seal, the turbine runner sealing system in linear, nonlinear stability of seal under the action of stress and critical instability speed. According to the influence of different parameters on seal instability critical speed, gives the system reduced, or even avoid self-excited vibration the route or measures, provide a reference for the dynamic design and stable operation of the unit runner seal system.

【学位授予单位】：大连理工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM312

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