Study On Water Resource Scheduling Model For "One-Reservoir-Two-Station" System Which Has "Supplying Reservior" And "Supplying Ditch" Conditions

Currently,the development of many areas of China are uneven because time and space distribution of water resources is restricted.Despite water resources is abundant in southern region of China,but due to time and space distribution,seasonal irrigation water shortage is still outstanding,therefore,it is necessary in the total water resources and the status quo of water source engineering limited cases to use the joint dispatching operation such as reservoir and pumping station has built projects to strengthen regional water resources optimization scheduling,management,to improve the utilization of water resources,and effectively ease the shortage of water in irrigation district.This paper,taking a single reservoir,a pumping station supplying the reservoir and a pumping station supplying the ditch as the research object under sufficient irrigation conditions,with a local water conservancy years difference between water demand and system’s water supply,the minimum sum of squares as the goal,each time the reservoir water supplying and a pumping station supplying the reservoirr supplying as decision variables,consider "reservoir-pumping station supplying the reservoir " subsystem in the total water supply,a pumping station supplying the ditch total annual allowed to carry water,reservoir scheduling rules and the reservoir of constraint condition,etc.,establish the south wet area has "single reservoir-single pumping station supplying the reservoir-single pumping station supplying the ditch "system with "supplying reservoir" pump station and"supplying ditch" pump station combined water supply,according to the characteristics of the model,using the successive approximation method of large system dynamic programming based on subsystem dynamic programming for solving,to obtain the minimum water shortage in the water demand area,reservoir optimal water supplying process or abandoning wate process,a pumping station supplying the reservoir and a pumping station supplying the ditch supplying process and water shortage.This optimization algorithm improves the solution accuracy.It not only obtains the objective function including two decision variables of water supply and water withdrawal in the pumping station supplying the ditch at each time period,but also obtains the optimal water abandonment process of the reservoir and water replenishment process of the pumping station supplying the reservoir by combining the water balance equation of the reservoir and the reservoir capacity constraint.At the same time,this method can be used for reference to solve the mathematical models with similar structural characteristics,and it can enrich the theory of system engineering optimization.Then,taking the system of "Niqiao reservoir-Nidong No.1 pumping station supplying the reservoir-Nidong No.2 pumping station supplying the ditch" in Niqiao irrigation area,Liuhe district,Nanjing city,Jiangsu province as an example.This paper analyzed the water supplying,water abandoning of reservoir,a pumping station supplying the reservoirr and a pumping station supplying the ditch supplying,and water shortage in the water demand area in three typical years(P=50%,P=75%,and P=90%)under conventional operation.Then,the subsystem dynamic programming method based on the large system dynamic programming successive approximation method was adopted to solve the water resources optimal scheduling of the system,and the results were compared and analyzed with the conventional scheduling results.The optimization results showed that water frequency P=50%the irrigation area can meet the water supply demand in all periods of the year,and there was no shortage of water.The replenishment of the pumping station at Nidong No.1 Station had been increased from 2,550,000 m3 to 2,900,000 m3,while Nidong No.2 Station was reduced from 710,000 m3 to 320,000 m3(the total amount of water pumped by the pump station was reduced by 40,000 m3)and the reservoir abandoned water was reduced by 40,000 m3(from 90,000 m3 to 50,000 m3).Water frequency P=75%,Nidong routine irrigation scheduling,a total of water shortage was 290,000 m3,after optimization scheduling,water shortage was reduced by 80,000 m3(reduced from 290,000 m3 to 21,000 m3),Nidong No.2 pumping station of water was from 950,000 m3 to 1,000,000 m3,Nidong No.1 pumping station of water was from 6,570,000 m3 to 6,500,000 m3(total reducing water pumping station 20,000 m3),there was no abandon irrigation water.Water frequency P=95%,Nidong routine irrigation scheduling,a total of water shortage was 1,270,000 m3,after optimization scheduling,water shortage was reduced by 130,000 m3(reduced from 1,270,000 m3 to 1,140,000 m3)Nidong No.1 pumping station of water was from 8,770,000 m3 to 8,720,000 m3,Nidong No.2 pumping station of water was from 1,450,000 m3 to 1,500,000 m3(as more as conventional scheduling),and there was no abandon the optimized irrigation water.Through the realization of optimal water resourced dispatching of the system under different water frequency,not only can give full play to the storage function of the reservoir,reduce the waste water and increase the effective water supply,so as to meet the water demand of the water demand area as much as possible,but also can reduce the water supply of the pumping station,reduce the energy consumption and cost of operation,and effectively improve the utilization of water resources.Finally,based on the Visual Basic software platform,water resource scalculation module for " one-reservoir-two-station" which has "supplying reservoir" and "supplying ditch" conditions has developed.Reservoir parameters such as flood control storage capacity,dead storage capacity,pumping station parameters such as pumping station supplying the reservoir and pumping station supplying the ditch,monthly and total water withdrawal,total water withdrawal,reservoir water intake,water demand in the receiving area,initial stage water extraction decision,iterative control accuracy,and other parameters.Through the calculation of the solution,the optimal water supply process for the reservoir,the optimal waste water process,the optimal water pumping process for the replenishment pump station,and the optimal pumping station optimal value of water extraction process and objective function.It can provide reference for the operation management of irrigation districts that use similar water supply system with one-reservoir-two-station.