Research on the hydraulic turbine vertical vibration power flow in the head cover system

Abstract

Abstract. On the basis of the prior models about the vertical vibration of the hydraulic vibration source, this research introduced a sub-system---head cover. Head cover is one of the main paths when vibration is transferred from the water vibration source to the stable structure. This essay aims to analyze the hydraulic turbine vertical vibration power flow in the head cover system. The research is based on the power flow theory and the probability perturbation method; meanwhile, it considered on the reciprocal coupling effect of the water machine parts and power house structure, etc. Therefore, the results of can clearly provide the random power flow of the vibration transfer path system, which including the head cover system, in frequency domain by given of some uncertain factors in one project. In conclusions, the research provide an overall analysis on the hydropower station vertical vibration transfer path; and it suggest some simplified and efficient solutions in the analysis on the vibration path with some random parameters. IntroductionIn the system of the hydropower station powerhouse and unit vibration, the fluid is the sole energy source of the vibration, as well as the moving medium; therefore, the hydraulic vibration is the main vibration source in the vibration system. It can be proved by the field and model experiments that there are three main transfer paths which transfer from the hydraulic turbine vibration to the powerhouse structure [1]. The three transfer paths are separately: (1) runner-shafting-bearing-fixed parts (machine frame, head cover)-powerhouse; (2) filling water pressure-spiral case-powerhouse; (3)runner-negative runner pressure area-head cover-powerhouse. Now, many researches about the vertical vibration of the hydraulic vibration source mainly focused on the path (1) and usually ignored the path (2) and path (3) [2]. With the development of the large scale and complication of the hydropower station structure, the including control parts and its weight of the head cover system increased continually, then its influence on the hydraulic vibration become more important. Therefore, the analysis on path (3) appears more important.The hydropower station vibration system problem belongs to the classic random structure system problem, due to the complexity of the hydropower station structure and the uncertainty of the parts production, installation as well as materials parameters. Now, the main methods, which are used to solve the random structure system problem, could be found the traditional Monte-Carlo simulation method, the second-order moment method, the probability perturbation method and the random finite element method, etc.. Meanwhile, many researchers analyzed the problem by using the power flow