Multi-objective Optimization Design Of Mountain Water Supply Network

As a critical part of the development of urbanization,water supply networks bear the responsibility of transporting water and ensuring water quality.The relevant departments have recommended new norms and regulations for water supply pipeline networks as science and technology evolve and people’s living conditions improve.The difference in elevation between the pipe network and the water source in mountainous-hilly areas is enormous.Hence,the overall pipe network has high energy consumption,and water hammer safety accidents frequently occur due to excessive pressure in the local pipe section;influenced by the topography,the layout of the pipe network is limited,and the distance of water supply is too long,so the reliability of the pipe network is low;restricted by external conditions,the mountainous water supply pipe network is mostly branch-like structure,and the flow rate at the end nodes of the pipe network is low.The water age is significant,so the water quality decreases.The study on the optimization design of the mountainous water supply pipeline network aims to reduce the pipeline network’s construction and operation management to guarantee water safety.In this paper,the characteristics of water supply pipe networks in mountainous-hilly areas are studied and explored from various aspects.The main work is as follows:1)The advantages and disadvantages of several common water demand prediction models were analyzed and summarized,based on which an improved gray prediction model method was proposed,with examples demonstrating the feasibility and stability of the proposed model.The results show that the improved gray prediction model has accurate and good prediction performance and can be used for urban water demand prediction.The fundamental equation of water hammer,stopping pump water hammer,and the boundary conditions of one-way pressure regulating tower are explained for the problem of the significant height difference of mountain water supply network,which is prone to water hammer safety accidents.The typical water hammer protection measures are compared in many aspects.2)Because of the problems with the mountainous water supply pipe network,this paper constructs the objective function with the annual conversion cost of the pipe network as the economic objective,the nodal rich head variance as the hydraulic reliability objective,and the nodal water age as the water quality safety objective respectively.This study proposes a mathematical mountain water supply pipe network model based on multi-objective optimization,taking into account relevant policy requirements and hydraulic conditions.3)The multi-objective optimization model of the water supply pipe network is applied to the example pipe network based on a mountainous town water supply pipe network project in Laoshan District,Qingdao.The results show that the performance indexes of the engineering scheme obtained by SPEA-Ⅱ algorithm optimization are better than those of the traditional optimization design method and NSGA-Ⅱ algorithm.Using Hammer as the analysis tool,water hammer simulation analysis is performed for three pipe diameter combination solutions optimized by the SPEA-Ⅱ algorithm focusing on different objective functions.Optimizing the parameters of the unidirectional pressure regulator tower yields the best engineering scheme.Subsequent water hammer protection measures are proposed for the pipe sections with potential safety hazards.