Abstract In this study, a secondary subsystem mathematical model is established under the condition that the layout of the sewage collection branch, trunk, and main pipe network projects is fixed. The sewage collection branch and trunk pipe network projects are treated as the research objective by taking the minimum annual cost of the sewage collection pipe network projects as the objective function, the longitudinal slope of the pipe section and the economic flow rate of the pipe section as constraints, and the diameter of the pipe section as the decision variable. A first-level subsystem mathematical model is established by taking the sewage collection branch, trunk, and main pipe network project as the research object. A large system mathematical model is established in the same manner. This model can be solved using the large system secondary decomposition–dynamic programming aggregation method, and the optimal diameter for each pipe section can be obtained. A regional sewage collection pipe network project in Taizhou city was considered as an example for comparative analysis before and after optimization, and the results verified that the optimization method proposed in this study can solve this complex large system optimization problem.

中文翻译：

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城市污水收集管网优化设计方法

摘要本研究在污水收集支管、干线和干管网工程布局固定的情况下，建立了二级子系统数学模型。以污水收集支干管网工程为研究目标，以污水收集管网工程年造价最低为目标函数，管段纵坡度和管段经济流量为约束条件，并以管段直径作为决策变量。以污水收集支管、干管、干管网工程为研究对象，建立一级子系统数学模型。以同样的方式建立大系统的数学模型。该模型可以采用大系统二次分解-动态规划聚合法求解，得到各管段的最优管径。以台州市某区域污水收集管网工程为例，对优化前后进行对比分析，结果验证了本文提出的优化方法能够解决这一复杂的大系统优化问题。