The Research On The Flow Control Of Construction Diversion Of Shuhe Hydroelectric Station

The size of construction diversion discharge determines project investment, which is one of the main factors to affect construction progress and safety of hydropower station project. It is critical to compromise between economy and safty. In cascade scrolling development of reserviors, by means of the storage of upper reservoirs, it is an effective approach to control the construction diversion discharge of building lower hydropower station. According to the characteristics of decreasing flow from the upstream of Hanjiang in last years and operation manner of Ankang reservoir, the comprehensive study on how to control the release of Ankang reservoir is done, corresponding to the standants during the different construction period. The main contents and conclusions are presented in this paper as follows:(1) The magnitude of characteristic indices of flood are partitioned by Golden-section algorithm, and the inflow characteristics of Ankang reservoir and the complexity of flood peak series are analyzed separatelly by the probability statistic theory and complexity theory, which are the basis of theory for the flood control of construction diversions at Shuhe hydroelectric station. It is convenient to calculation and requires shorter time series for complexity theory, so it is worth in practice.(2) Due to the change of characteristic indices that caused by sedimentation, the capacity of reservior flood control and the storage-outflow of Ankang reservior need be checked. With multiannual flood data and existing operation manner, and the manner of release from Ankang reservior and operation rules are presented to attain the goal of optimizing construction diversion discharge of Shuhe power station, reducing the investment and shorting construction time, to different initial levels made different construction stage of Shuhe station.(3) The capacity of storage-outflow is analyzed by many different combinations of over-impoundment level, base flow and outflow, and then the relation of storage level andintervals between floods is deduced under different release during critical construction period of Shuhe power station.(4) Owing to the regulation of Ankang reservoir, the temporal distribution of natural flood downstream, the flood peaks and quantities were changed, and the probability distribution of flood at dam site of Shuhe hydropower station is also changed. Aiming to the characteristics of flood in Ankang, Shuhe and interval, the design flood at dam site of Shuhe hydropower station is estimated with probability combination method.(5) MC method is selected to calculate the diversion risk of Shuhe because it has many advantages such as little impact of condition limit, easy to realize and improve. To reduce the much sampleing times, the improvement has been made for MC method, which is sampled by Latin hypercube sampling and antithetic variates with variance reduction technique. The Sampling times of improved model are greatly reduced, and the vaule distribution input into the probability function is more accurate. The results show that the construction diversion risk of Shuhe power station is related to the operation conditions of Ankang reservoir. The flood control and release of Ankang reservoir is an efficient and feasible manner to reduce the difficulty of construction diversion risk of Shuhe hydropower station.The study is supported by the Shaanxi Hanjiang Investment and Development Ltd.(HJSH-05-24).