Valve Layout And Regulation Optimization Of Multi-source Water Distribution Systems Based On Critical Location Analysis

Water distribution networks with multiple sources are generally adopted in cities due to the increasing urban water supply scale and the demand for water supply safety.However,the multi-source water supply may have some adverse effects,although it can improve the urban water-supply guarantee rate.Suppose the supply areas were not planned and appropriately adjusted.In that case,it may lead to an unbalanced multi-source water supply pattern,which refers to the situation of the actual water supply area of the water plant deviating from the designed scheme.In this situation,the water supply enterprise would face enormous operating pressure because the actual supply amount of some water plants is below the designed supply amount.The problem mentioned above can be solved by installing valves to adjust the water supply area of each water plant.Most water distribution systems have complex structures and large scales,so it is challenging to locate the positions of critical valves and determine reasonable valve control schemes.This would result in the difficulty of solving the unbalanced multi-source water supply pattern.Therefore,this thesis proposed an optimization method for valve layout and regulation based on critical position analysis,which provided an effective method for solving the unbalanced water supply pattern in a multi-source water distribution network.On the one hand,this method was able to find out the limited critical valve positions in the vast distribution network.On the other hand,establishing a many-objective optimization model enabled a comprehensive evaluation of the impact of valve layout and regulation on the water distribution network from diversified aspects.The optimization method for valve layout and regulation based on critical position analysis was divided into two parts.The first part was to screen the critical positions of valves,and the second part was to optimize the valve layout and control.In the first part,screening the positions of the critical valves included the following steps:（1）determining the strong and weak water sources,transitional nodes,and critical nodes;（2）analyzing the critical path and determining the positions of critical valves.After screening critical valves,the second part sought a reasonable valve layout and control scheme by constructing a many-objective optimization model and solving it using the Borg algorithm.The optimization model took the locations of valves and the valves’ opening degrees as decision variables.The model was aimed at minimizing the background leakage percentage of a network,the standard deviation of the node pressure in a network,water age,the number of valves and the diameters of the installed valves,and maximizing the pressure redundancy and the increase percentage（IP）of the weak water source（s）.The above methodology was applied to two benchmark networks,namely JYN and BJ.Results showed that the representative solutions of JYN and BJ identified three and five critical valves,respectively,and these important valves were located in the main pipelines of the strong water sources,which effectively adjusted the water supply areas of the strong and weak water sources.After installing the valves,the numbers of nodes within the water supply areas of the weak water sources of JYN and BJ increased by 6 and 228,respectively,and the corresponding water supply amount increased by 8.33% and 16.6%,respectively.The conclusions of this thesis are as follows:（1）the optimization method for valve layout and regulation based on critical position analysis effectively screened out the positions of critical valves within water distribution networks.（2）The unbalanced water supply pattern was solved through reasonable valve layout and control because the water supply area of weak water sources significantly increased.（3）The impact of valve layout and regulation on the water distribution network’s hydraulic and water quality aspects showed a specific pattern: the standard deviation of the node pressure increased with the increase of IP.In contrast,the network’s background leakage percentage and pressure redundancy decreased with the increase of IP.The water age was not significantly affected by IP.