Research On Coupling Vibration Characteristics Of Generator Set And Hydropower House

With the development of the economy and society, people pay more and more attention to the hydropower. And it has been developed rapidly as a regenerated energy source. The unit capacity has been sharply increasing. The hydropower house is becoming larger and more complex correspondingly. As a result, the vibration problem of water turbine generator set and hydropower house is standing out gradually, which become an important issue during the design and operation. Presently, the coupling among the magnetic, hydraulic and mechanical vibration sources, the coupling vibration between the generator set and the hydropower house and the parameters identification method of the generator set should be improved. Thus this paper studies on the dynamic characteristic of the generator set the vibration of hydropower house under all kinds of vibration sources loads. The methods of numerical simulation through finite element, model test and parameters identification according to prototype test are used in this paper. The analytical model, methods and conclusion provide a reliable technical support and reference for the structure dynamic design and study of generator set and power house.Chapter one simply introduces the vibration of water turbine generator set and hydropower house and its study situation. This part also simply summarizes the dynamic characteristic of connecting structures such as journal bearing and thrust bearing, some vibration sources loads, the vibration of the hydropower house and some parameters identification methods.In chapter two, the model of the generator set shaft system is constructed including the journal bearing and thrust bearing. The finite element method is used to calculate the dynamic characteristic coefficients of the bearings. The dynamic behaviors of the fluid supports are considered as nonlinear with the corresponding parameters. The influence of the axial thrust bearing is presented on the response of the shaft. The coupling effect is studied in particular between the bending vibrations and the axial dynamic behavior of the shaft.In chapter three, the dynamic stability of the generator set shaft system is investigated considering the influence of the magnetic and seal stiffness. First, the dynamic equations are established including the magnetic stiffness and elastic support. The Liapunov nonlinear vibration stability theory is used to analyze the shaft system stability. Second, the model of the shaft system is constructed considering the magnetic and hydraulic seal vibration source. The influence of all kinds of system parameters is studied to the critical speed of the shaft system.In chapter four, the coupling vibration is studied between the generator set and the hydropower house considering the constantly change characteristic of the journal bearings coefficients. The coupling vibration model is constructed. The dynamic characteristic and interaction between the generator set and the power house are analyzed. According to the comparison of different calculation models, the influence of the power house is studied as the supporting structures to the shaft system dynamic characteristic. Otherwise, the effect of the generator set vibration sources is also presented to the power house vibration.In chapter five, the vibration mechanism is analyzed according to the prototype test. The characteristic of the vibration sources and its transmission routes are investigated. The vibration of the generator set and power house is evaluated according to the corresponding rules. The finite elements method is used to calculate the dynamic response of the power house.In chapter six, the multiple signal classification method is used to determine the order of the vibration, the time domain identification is introuduced to the study of the generator set shaft system dynamic characteristics. Because of the deficiency of the classical identification methods for the bearing characteristic coefficients, the genetic method is presented which has few limits of actual conditions such as measuring points or operation cases. The identification coefficients are used to calculate the self-vibration characteristic of the shaft system. The results are in accordance with that of modal parameters identification.