Study On Dynamic Characteristics And Monitoring Of Large-size Power-house Of Power Station At Dam Toe

With the continuous increment of unit capacity and physical dimension of hydropower house, more and more people have regard for the vibration problem of the hydropower house in large-size hydrostation. But now the research into this problem is not to be compared with the study on the problem of vibration of water-turbine generator set. Now more people pay attention to this problem step by step because of the appearance of vibration problem of hydropower house in some large-size hydrostation at the last twenty or thirty years.The complexity of this problem result from the complexity of hydropower house structure and vibration source, specially the source come from hydraulic power factor, itself characteristics, the mode of action, mode of transmission is the key of this problem. The contents of this paper with the Three Gorges Project as the study object is as follows.The natural vibration characteristics of the power-house which included frame superstructure, generator floor layer and power-house substructure is studied in detail, the effect of the boundary condition and associate power house is considered, further more the distribution law of the vibration shape is analyzed.For the water fluctuating pressure in the pressure retaining volute, the mode of transmission is researched, and the effect on the dynamic response at different mode of action and different number of periodic is researched too. Especially the relationship between the response and the frequency is analyzed. The mode of transmission of the particular fluctuating pressure band between the wicket gates and the runner is studied, the fluctuating pressure is expressed as the direct vibration source of power-house under some assumed condition. Besides the effect of the damping ratio on the dynamic response is studied. On the base of those study, the dynamic response of the generator floor layer in the Three Gorges Project is forecasted when the water level reached elevation 156m.The last, the dynamic monitoring problem of the large-size hydrostation power-house is discussed from the system composition, sensor characteristic, sensor distribution, error source, sampling frequency aspects, and the dynamic monitoring system in the Three Gorges Project is appraised.