| Currently,the issue of leakage in urban water distribution networks has been a global focus of the water supply industry.Leakage within the network not only results in significant water waste,but also poses a significant threat to the quality of water in the network.China,in particular,is facing the challenging situation of having a large total water resource,but a small per capita possession.As such,the reasonable distribution of pressure within the water distribution system to effectively control network leakage has become a primary focus of research and analysis within the water industry.The objective of this study is to establish a reasonable pressure distribution for a large and medium-sized water supply network in the CYB area of a northern city.This will be achieved through the development of a DMA zoning scheme,the optimal arrangement of pressure reducing valves within the pipe network,and the joint regulation and control of pump station valves.The ultimate goal is to optimize the hydraulic operation conditions within the pipe network,with the aim of reducing leakage.The specific research objectives include:(1)The basic theory related to DMA zoning in urban water distribution networks is described.Firstly,it introduces the fundamental concept of DMA zoning,including its purpose,advantages,and disadvantages.It then summarizes the principles that should be followed in the design of DMA zoning,the specific workflow of DMA zoning,and the work management and daily maintenance measures that should be implemented after the scheme is put into operation.(2)Part of the pipe network in CYB area of a northern city was studied as an engineering example.Firstly,the DMA zoning scheme was developed by integrating all conditions,and the rationality of the scheme was verified by calculation.After that,the hydraulic and water quality conditions before and after zoning were compared and analyzed,the pressure distribution and water age distribution of the pipe network at the time of maximum water use were drawn,and the delayed change of water age of the nodes was analyzed by selecting several proposed most unfavorable points in the pipe network.(3)A typical slice of pipe network in CYB area was selected as the research object,and genetic algorithm was used to optimize the optimal number and location of valves in the pipe network,and its coding problem was solved by setting the coefficient C value in the pipe.Using the intelligent optimization search results,the corresponding pressure reducing valve deployment was carried out in the pipe network model.Then,EPANET was used for hydraulic simulation,and the calculation of pressure and leakage loss was carried out for the minimum and maximum water use,and the pressure distribution diagrams of the pipe network under different conditions were drawn for comparison and analysis,and the best deployment plan of pressure reducing valves was finally determined.(4)On the basis of determining the optimal number and location of pressure reducing valves in the pipeline network,a pressure leakage control model with joint regulation and control of pumps and valves is established in collaboration with pumping stations.The model is solved by using the gray wolf optimization algorithm and improved by introducing the DLH search strategy.The optimal regulation scheme of the example pipe network in each operation period of the day is also derived.Finally,the optimal solution is brought back to the hydraulic model of the pipe network and re-simulated,and the average pressure and leakage volume of the pipe network for each time period before and after optimization are calculated and compared for analysis to verify the reasonableness of the scheme.The optimal regulation method of water supply network pressure discussed in this paper can play the role of reducing the redundant pressure of pipe network operation as well as effectively controlling the leakage level of pipe network,which has obvious theoretical value and practical application prospects. |
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