【作者】 安学利；

【导师】 周建中；

【作者基本信息】 华中科技大学 ， 水利水电工程， 2009， 博士

【摘要】 水力发电系统是一个水机电耦合的复杂非线性动力系统，其运行过程中水电机组故障的产生和发展包含大量的不确定性因素，难以用数学模型对其进行精确描述。同时，随着水力发电机组日趋大型化、复杂化、自动化，转子系统的非线性振动现象异常突出，由此引发的非线性动力学行为引起学术和工程界的广泛关注。因此，深入研究水电机组的动态行为，获得机组故障征兆描述的有力证据，解析机组故障的成因及其演化机理，实现水电机组的安全、可靠和高效运行，具有十分重要的理论意义和工程应用价值。考虑到振动问题在机组运行中的普遍性，本文对刚性联接平行不对中转子系统动力学特性、轴向推力作用下碰摩转子运动机理和水电机组轴系振动特性进行了系统的理论分析，同时对机组振动故障诊断策略进行了深入研究。论文的主要研究成果如下：(1)在分析转子系统平行不对中机理的基础上，建立了刚性联接平行不对中转子系统运动方程，为更好地探寻不对中转子系统动力学机理，对所建立的不对中转子系统微分方程进行了深入的理论分析，应用数值仿真方法验证分析结论。研究表明，刚性联轴节平行不对中时，故障特征频率主要为驱动轴频率；振动经过充分衰减后，转子系统轴心轨迹是比较稳定的圆。在转子系统中，质量偏心、联轴节平行不对中量、驱动轴转子质量和从动轴转子质量等取不同值时，驱动轴、从动轴振动幅度变化较为复杂。(2)通过对轴向推力作用下碰摩转子运动的解析，建立了碰摩转子在轴向推力作用下的非线性动力学模型，详细分析了转子转速比、质量偏心、摩擦系数、系统阻尼等参数对轴向推力作用下碰摩转子动力学特性的影响。分析发现，随着转速比、质量偏心、摩擦系数、系统阻尼等参数的变化，转子系统的振动特性的变化非常复杂，可能会出现周期运动、拟周期运动和复杂的混沌振动。(3)建立了水力发电机组动力学模型，分析水电机组发电机转子、水轮机转子及轴承之间的距离对机组振动特性的影响。研究发现，随着水轮机转子质量偏心的不断增加，发电机转子、水轮机转子的径向位移都近似线性增大。随着水轮机转轮叶片质量、发电机转子质量偏心、轴承之间的距离的不断变化，转子系统响应主要是简单的周期运动，但在局部会发生复杂的拟周期运动。(4)针对水力发电机组存在故障机理极其复杂、诊断系统实时性差、现有故障识别方法的诊断结论不甚理想等方面的问题，吸收并发展故障诊断理论的最新研究成果，将信息融合技术引入到水电机组振动故障诊断中，充分挖掘不同信息源的数据以及专家经验等获得机组故障相关信息，建立了熵权理论、灰色关联分析和证据推理技术相结合的水力发电机组故障诊断模型。该模型采用基于熵权的灰色关联分析方法对水电机组振动故障进行了初步诊断，然后对初步诊断结果应用证据理论进行有效的信息融合，按照最大关联度原则，获得水电机组的最终诊断结论。该诊断方法能够充分利用机组不同故障源提供的有效信息，抑制单一故障源的诊断局限性，可较好地确定机组故障的类型和部位。更多还原

【Abstract】 With the rapid development of social economy and the sustained and rapid growth of electricity demand, the single unit capacity of the hydro-generating unit continues to increase; the safe and reliable operation of the units is directly related to the safety of hydropower plants and the stability of interconnected power system. Once a failure for generating units occurs, it may cause the plant to non-planned shutdown or reduce capacity, even serious heavy casualties and serious damage to the system may appear when encountering major accidents of units. Due to the universality of the vibration when the unit in the operation, the theoretical analysis of the vibration characteristics on hydro-generator shaft system is made, which studies the dynamic characteristics of two rotors connected by rigid coupling with parallel misalignment and the rotor rubbing under the axial thrust. At the same time, the vibration fault diagnosis strategies for the hydro-generating units are further researched. The main contents of the paper as follows:(1) The dynamical equation of parallel misalignment rotor-bearing systems is derived using Lagrangian dynamics. The effect of the rigid coupling parallel misalignment and the rotor unbalance is examined with theoretical and numerical analysis, where the numerical simulation methods are applied to verify the conclusions of the theoretical analysis. At steady state condition, the 1X-rotational speed excitation is presented in the lateral vibration direction, which indicates that parallel misalignment of the rigid coupling can be a source of lateral excitation. The axial locus of the rotor systems is a steady circle after full decay. Simulation results showed the changes of the amplitude of the driving shaft and the driven shaft are more complicated with the changes of the rotor mass eccentricity, the rigid coupling parallel misalignment, the rotor mass of the driving shaft and the driven shaft etc. The effect of the transient response on the parallel misalignment to the rotor-bearing systems with less bearing stiffness is stronger.(2) A model of a rigid rotor system under axial thrust with rotor-to-stator is developed based on the classic impact theory and analyzed by the Lagrangian dynamics. The effects of rotating speed, mass eccentricity, friction coefficient, and damping coefficient on dynamic characteristics of the rotor system are researched. With the changes of these parameters, the changes of vibration characteristics of rotor system turn to be very complicated, and the periodic motion, complicated quasi-periodic motion, or chaotic motion may occur in the response of the rotor system.(3) The kinetic equation for a hydrogenerator set system is deduced and the motion differential equation is simulated using numerical methods. Considering the effect of generator rotor’s mass eccentricity, hydraulic turbine rotor’s mass eccentricity, blades mass and the distance of guide bearings, the lateral vibration characteristics of the hydrogenerator set system are analyzed. Research results demonstrated that the radial displacement of generator rotor and hydraulic turbine rotor increases linearly with the increase of hydraulic turbine rotor’s mass eccentricity. There mainly appears relatively simple periodic motion of the rotor systems, but accidentally the more complicated quasi-periodic motion may occur with the changes of blades mass, generator rotor’s mass eccentricity, and the distance of guide bearings.(4) Considering that the complexity of diagnosis process and the diagnosis conclusion is not satisfying as expected for the vibration fault diagnosis of the hydraulic generator units, the information fusion technology is introduced to the units fault diagnosis, which enable us to make full use of different information sources of data and expertise to obtaine the relevant faults information of units. On this basis, the vibration fault diagnosis model of the hydraulic generator units is established using entropy weight coefficient, grey incidence analysis and information fusion technology. Taken the vibration spectrum characteristics and amplitude characteristics as the fault diagnosis samples, an initiative vibration fault diagnosis of hydraulic generator units is accomplished based on grey incidence analysis and entropy weight coefficient. The final diagnosis results are deduced by fusing different evidences using Dempster-Shafter theory. This diagnosis method can take full advantage of the effective information of different faults source of the hydraulic generator units, and also can restrain the diagnosis limitations of the single fault source. Thus this diagnosis method is able to better determine the type and location of unit faults. Diagnosis example demonstrated that the proposed method is a good candidate to be used as an online diagnosis tool for hydraulic generator units.更多还原