Study On Joint Optimal Dispatch Model Of Water Supply And Power Generation For The Yangtze River Giant Reservoir Group

With the rapid development of the Yangtze River Economic Zone,the water demand in the middle and lower reaches of the Yangtze River has become higher.The uneven spatial and temporal distribution of runoff in the Yangtze River Basin leads to the prominent contradiction between regional water supply and consumption.At the same time,with the construction of cascade reservoirs in the middle and upper reaches of the Yangtze River,it is possible to jointly compensate water supply dispatch between reservoirs.And it has become an effective method to resolve the contradiction between supply and demand in the Yangtze River Basin.This paper is aimed at the water demand of five provinces and one city in the middle and lower reaches of the Yangtze River,and carries out research on the Joint optimal dispatch model of water supply and power generation for the Yangtze River giant reservoir group.The main research contents and achievements are as follows:Firstly,the study carries out the analysis of the runoff characteristics of the reservoirs in the Yangtze River Basin and the supply and demand of water resources.The spatial and temporal distribution of reservoir runoff in the middle and upper reaches of the Yangtze River is uneven.On the time scale,the in-year distribution of runoff shows obvious seasonality,and the annual variation is relatively stable,but there are extreme inflow conditions.On the spatial scale,there are obvious regional characteristics between the river basins,and the runoff difference is large.The study extracted the typical years of the basin and the parameters related to the main cycle based on the ratio of abundant and dry stations and the wavelet analysis.On the basis of factors such as the proportion of water extracted from rivers in five provinces and one city,and the convergence of rivers and lakes in the middle and lower reaches of the river basin,we calculated the water demand process of each control section and calculated it into the Three Gorges section to obtain the typical water demand process of the Three Gorges section.The annual demand water flow rate is above 7000m~3/s,and the main supply and demand contradictory period is located in the water supply period of the basin reservoir group.Secondly,this paper studies and develops the joint optimal dispatch model of water supply and power generation for giant reservoirs in the basin.In this paper,an optimal dispatch model for combined water supply,power generation and water storage targets of reservoir group is established.For the optimal dispatch model,the model solving framework and the model solving method using NSGA-II algorithm are proposed.Thirdly,the paper carries out research on joint water supply and power generation dispatch strategy for the giant reservoir group in the Yangtze River Basin.We use the proposed optimal dispatch model to get the optimal dispatch scheme group,including the order of using reservoir capacity to compensate water supply and the allocation scheme of compensated water supply.The results show that the water requirement of the middle and lower reaches can be met in all typical cases after optimization,and the factors affecting the decision-making of river basin dispatching are the power generation performance,storage capacity and geographical location of reservoirs in the river basin.We propose(1)reservoir group compensation water supply allocation strategy:The Yalong River and the middle reaches of the Yangtze River are the main and adjustable compensatory water supply basins respectively.The other basins are the alternative compensatory water supply basins.The suitable compensatory water supply for the reservoirs in the upper reaches of the Three Gorges is 25 billion m~3 to 30 billion m~3.(2)Selection strategy of reservoir group dispatch mode:When encountering abundant water and abundant water-normal year,the reservoir group operates according to the established dispatch rules,supplemented by joint dispatch mode.In normal and normal-dry years,joint dispatch mode should be implemented to maximize the hydrological compensation capacity of inter-basin reservoir capacity.Sufficient joint dispatch should be carried out when encountering dry years,and necessary storage and discharge adjustments should be made taking into account the possibility of continuous dry water in the future.(3)Suggestions on joint water supply-power generation dispatch for reservoirs in each basin.