Research On The Joint Water-dissipation Mode Of Large-scale Series-parallel-mixed Reservoir Group In The Upper Reaches Of The Yangtze

With the successive completion of a large number of large-scale water conservancy projects,the scale and topological structure of the hydropower energy system in the upper reaches of the Yangtze River have become increasingly complex,and competition and conflicts between single reservoirs and cascades,river basins and the system as a whole have gradually intensified.If large-scale reservoir groups operate in the original flow-down mode,and maximize the benefits of sub-basin basins,it will deplete the overall economic benefits of the basin and even cause artificial flood peaks downstream.In order to meet the goal of overall optimization and the demand for efficient use of water energy resources,it is urgent to establish the theory and method of drawdown and dispatch suitable for largescale series-parallel-parallel reservoir group systems,and guide the large-scale reservoirs on the upper reaches of the Yangtze River to arrange the flooding in an orderly and reasonable manner.This article conducts an in-depth study on the related problems faced,specifically including the following three aspects:(1)First,in order to get rid of the discrete problem of power generation in the solution process,according to the data range that needs to be used in the actual scheduling work,linearly fit the characteristic curve of each reservoir.Based on the understanding of the original flow-down mode of the reservoir in the study area,and the multi-year measured runoff data from the control stations in the upper reaches of the Yangtze River,mathematical statistics are used to explore the inter-annual variation characteristics and intra-period distribution of runoff during the dry season,and analyze and carry out During the critical period of the drainage work,the research provides data support for the joint drainage dispatching of the upper reaches of the Yangtze River.(2)With the goal of maximizing power generation,construct a joint water-level dispatching model for cascade hydropower stations.The mathematical mechanism of the increase in power generation during the decay of the reservoir during the two adjacent periods is explored,and on this basis,the optimal regulation flow calculation method for the first period is deduced.After the above-mentioned exploration process,a step-by-step optimization algorithm(APOA)coupled with fallout analysis is proposed.The research results taking the middle reaches of the Jinsha River as an example show that the accuracy and convergence speed of this method are further improved compared with the traditional POA algorithm.(3)Taking 29 series-parallel-mixed reservoirs in the upper reaches of the Yangtze River as the research object,the idea of zoning control is adopted to construct virtual zoning of the reservoirs,and from the perspective of overall optimization,a large-scale reservoir group zoning drainage dispatching model is established.The sliding process of the drawdown is divided into two periods,and a drawdown criterion with a period scale coefficient is proposed based on the analysis.On this basis,a partitioned stepwise optimization algorithm(DPPOA)based on coupling and fallout criteria is proposed.A case study in the upper reaches of the Yangtze River shows that compared with the traditional POA solution,this method has a relatively stable improvement in solution accuracy,and provides a new idea for the optimal operation of large-scale reservoir groups.The drawdown plan generated at the same time provides a reference for the regulation of the dry season in the upper reaches of the Yangtze River.