The Dynamic Aanalysis Of Underground Hydropower Station And Modal Identification

In recent years,with the development of the hydroelectric engineering, the turbines has developed to high head , large capacity, high speed; correspondingly, the powerhouse structure has complicated.At this point, the vibration problems of the concrete structure caused by the turbine swing or the hydrodynamic pulsation are become the focus of the design and running process.Based on one powerhouse, this paper studies the dynamic characterristics of the unit foundation composite structure and the vibration characteristics of the upper structure in the pusulation pressure, by setting 3-D model of power station. The content of specific reseach as follows:(1) Before the dynamic characteristic of the underground powerhouse, the thesis researches the influence of the boundary selection on the Self-vibration characteristics. In this paper, the the fixed boundary and elastic boundary, and consider a range of surrounding rock of underground powerhouse are be considered. At the same time, the boundary condition is helpful in dynamic and resonance check of powerhouse. There are several different models in the paper, they include finite element model of powerhouse without surrounding fock and finit element model of powerhouse with surrouding rock. We ignore the damp when researching the influence of boundery selection on the frequency of the underground hydropower house.(2) Due to the powerhouse vibration are caused by complex factors. Therefore in this paper analyzed the influence of vibration of hydraulic, mechanical, electrical and so on, the accurate calculation of the theory source, and the corresponding source of resonance. Analysis of the power station during operation theory of the existence of the resonance source.(3) As the main unit and the support system, the structure of combination machine pier stiffness and strength of stability is very important. Based on the design of hydropower plant is stipulated in the code, using the pseudo-static method and dynamic method for pier stiffness of the composite structure. Basically, the machine pier stiffness of the composite structure basically meets the standard requirement.(4) According to the variable load operation conditions of the slab structure, the measured data and the finite element calculation of linear regression analysis. In different operating conditions, fit out a sutiable predication linear equation of the slab structure. It has certain reference value for the vibration of slab structure and running of the hydropower station.(5) Based on summarizing and analyzing the volute tail water pressure pulsation of the selection, one of the most unfavorable loading methods, namely hypothesis fluctuating pressure turbine runner is in phase with the uniform distribution and the harmonic loads on the workshop with water, spiral structure by harmonic response calculation method, the upper structure building resonance frequency.