Study On The Wave Superposition Of The Transient Process Of Hydropower Station

With the swift development of the hydroelectric project in our country, a set of large or extraordinary hydropower stations are being designed or constructed, such as the Three Gorges hydropower station, Longtan hydropower station, Xiangjiaba hydropower station, Xiaowan hydropower station, Pengshui hydropower station etc. All these hydropower stations adopt underground workshop, and have long diversion pipe system, and have one or two surge-chambers or adopt tailrace tunnel with sloping ceiling. There exits different fluctuation in the diversion pipe system, the superimposition of them can bring unfavorable influence on the parameter of the guaranty calculation of regulation of the hydro-turbine, surge water level of the surge-chamber, the base plate pressure difference of the throttled surge chamber and the linear pressure distribution. These parameters directly relate to the structure design and safe operation of the hydropower station.Many researchers studied the influence of the superimposition ago, they mainly limit to study the influence on the surge water level of the surge-chamber, only few literatures mentioned the influence on the other parameters, but it isn't be studied in-depth. This paper analyze and study the influence of the superimposition in depth based on the previous achievements and combined with the theoretical qualitative analysis and project instances. The main contents as follow:Chapter 1: Indicate the significance and objective of this paper, review the previous achievements of the transient process and superimposition, and then present the study purpose of this paper.Chapter 2: combined with the physic knowledge of the fluctuation and the superimposition, Indicate the physical essences and the influence of the superimposition phenomena that exist in the diversion pipe system, and take one hydraulic turbine owning only one diversion tunnel and two hydraulic turbines sharing one tailrace conduit for instance to study out the numerical calculation superimpose operations.Chapter 3: From the calculation theory of the parameter of the guaranty calculation of regulation of the hydro-turbine, qualitative analyze the influence of the superimposition onthem and the superpose time, combined with some project instances, get the numerical value of the influence of the superimposition and the superpose time.Chapter 4: Based on the previous achievements of the calculation and theoretical analysis of the surge-chamber ground swell, analyze the influence of the superimposition on it and the superpose time. Combined with the surge-chamber ground swell calculation of some plants, get the numerical value of the influence of the superimposition and the superpose time; From the calculation of the plate pressure difference of the throttled surge chamber, analyze the numerical value of the influence of the superimposition on it.Chapter 5: Based on the analytic calculation of water hammer, indicate the linear pressure distribution in the diversion pipe system and the calculation operation of its maximum numerical value, combined with some project instances, analyze the the influence of the superimposition on it behind and before the surge-chamber.Chapter 6: Summarize the whole paper, and present the future research directions and emphasis.