城市供水系统多水源联合调度模型及应用

Modeling of joint operation for urban water-supply system with multi-water sources and its application

从城市供水系统的关键元素出发,通过系统网络拓扑分析,构建了"水源—水厂—分区用户"三层供水系统网络拓扑结构;基于此拓扑结构和兼顾整个供水系统的社会效益和供水成本两个调度目标,建立城市供水系统的多水源联合供水优化调度模型;利用NSGA-II(Non-dominated Sorting Genetic Algorithm II)算法进行模型求解,并给出最佳均衡解的选择规则;将该模型应用于南水北调中线一期工程通水后的天津市供水系统。实例研究结果表明,该模型实现了天津市不同来水丰枯组合情景下多种水源的合理分配,能够为决策者提供均衡社会效益与供水成本的详细供水方案,还可以在一定程度上反映出供水系统存在的工程问题,可为保障城市供水安全提供技术支撑。如最不利典型年来水情景下,总可供水量(14.73亿m3)大于天津市总需水量(13.77亿m3),但由于供水工程能力限制,特定供水规则下推荐的社会效益与供水成本折中方案的缺水量为2.44亿m3、总供水成本为32.6亿元。

Joint operation of multiple water sources plays a significant role in alleviating the conflict between urban water supply and demand. Firstly,to achieve the effective distribution of various urban water sources,an optimization model based on the network topology of ＂Source—Plant—User＂urban water supply system is proposed. The objectives of this model include social benefit and total water supply cost,subject to the capacity of water sources,water pipes and water plants,and the water demand of users. Secondly,NSGA-II algorithm is applied to solve the model,based on which the optimal condition for the equilibrium solution is obtained. Thirdly,as a case study,the water-supply system in Tianjin city is a complex multi-source water-supply system after the Mid-route of South-to-North Water Diversion Project（ SNWDP） begins to divert water to Tianjin. The optimization results show that this model could successfully provide corresponding reasonable allocation solutions compromising social benefit and water supply cost under different wetness and dryness probabilities at water sources. And the causes of water shortage and the existing design deficiency in the urban water supply network could be reflected through result analysis. For example,the water supply capacity（ 1 473 million m3） of the worst condition could satisfy the water demand of Tianjin（ 1 377 million m3）;whereas,the water shortage of recommended solution,which balances the social benefits and water shortage,is 244 million m3with water supply cost of 3 260 million yuan due to the capacity restriction of the pipelines under the specific water supply rule. Above all,this model is feasible to a certain extent and provides technical support for ensuring urban water-supply security of Tianjin city.