Study On Different Connections Between Floors And Walls And Vibration Isolation Of Devices In Main Powerhouse

With the sustained development of Chinese economy, energy demand is growing fast. With international energy forms and climate change issues becoming more complex, a variety of constraints and contradictions of Chinese energy development become more serious. China has the most water energy resource in the world. As clean energy, hydropower has mature technology and stable output, which can not only meets the requirements of low-carbon economy, but also has comprehensive benefits of flood control, irrigation, water supply, shipping, tourism, etc.. Therefore, it has broad development prospects. Besides, as the most economical way of large-scale energy storage in the world, pumped storage power station plays an important role in peak shaving, assurance of power supply quality and promotion of new energy accommodation in power grid. As powerhouse is the main bearing body of unit dynamic load and hydraulic pulsating load, vibration of powerhouse structure is very common both domestic and abroad, and research on vibration of powerhouse structure is important. In this paper, facing the problem of vibration of equipment, different connections between floors and walls and vibration isolation of devices in main powerhouse are analyzed using finite element method, thus providing a reference for powerhouse structure design and vibration control of devices in the future.In this paper, the following studies are conducted:1. For different calculation methods of floor natural vibration characteristics, we compare the natural frequency and mode shape of generator floor slab calculated by the whole mass of overall structure and the partial mass of local structure. The results show that the second method can reflect mode shapes and vibration laws better, but the natural frequency is little less than the first method when the two mode shapes are the same. So the second method is no big difference with the first method. Besides, it needs less mode orders to calculate and is processed more easily.2. For different connections between floors and walls (fixed connection and lapped connection), we compare natural vibration characteristics of different parts of main powerhouse superstructure and displacement and stress response under the influence of unit dynamic load, fluctuating pressure and bidirectional earthquake. The results show that the connection has large impact on natural vibration characteristics of floors and upstream and downstream walls and columns, and small impact on overall vibration of powerhouse. The fixed connection can significantly reduce lateral vibration of upstream and downstream walls and columns under the influence of unit dynamic load and bidirectional earthquake. The two connections both have advantage and disadvantage in dynamic responses of different parts of powerhouse structure under the effect of fluctuating pressure.3. By using spring-damping vibration isolator to device foundation, we study the impact of natural frequency, damping ratio, horizontal and vertical natural frequency ratio, the arrangement, floating foundation mass on isolation effect. Studies have shown that natural frequency of isolation system has a large effect on isolation effect. It needs to be determined combined with the dynamic load characteristics, vibration characteristics of the structure and vibration response of device foundation under dynamic load. Damping can reduce vibration response of isolation system to low-frequency vibration source, and it has significant effect on vibration response of the resonance region. Large mass of floating foundation can reduce vibration response of isolation system to vibration source of medium-high frequency. The impact of horizontal natural frequency of isolation system and isolator arrangement on vertical vibration isolation effect can be ignored.