基於制水閥分區之自來水管網損壞與維護決策支援系統

Abstract

供應安全、穩定與適飲的自來水，是維持現代社會民生需求的重要議題。然而自來水管網可能因管線破裂、漏水而影響用水端的供水品質，因而需要參考可靠的損壞影響分析，執行合理的管線更新、停水維護與設置有效的損壞污染監測網等工作，以確保管網的供水品質。 本研究因而以制水閥分區為維護管理分析的最小基本單位，簡化管網分析的複雜度，發展維護影響分析工具，應用管網的連通關係，判別直接影響及被關閉的下游分區，評估對其他區域的供水影響。亦採用考量水壓變化的水力損壞演算程序，發展用戶缺水影響模擬程序，以合理分析管線維護管理的影響。並將所發展損壞分析法應用到以往所發展的換管模式中，決策更恰當的換管策略。 制水閥損壞將擴大管網損壞維護的影響，本研究因而以制水閥分區為單位，發展受制水閥影響的損壞路徑演算程序，分析個別損壞可及路徑之損壞機率與損壞缺水影響量，以制水閥損壞可能擴大影響的期望值為其關鍵性量值，判識個別制水閥的關鍵性，供研擬制水閥維護策略之參考。 管網系統埋藏在地底，不易有效掌握水質變化，因此需建立有效的水質監測站網。過往雖有利用管網傳布關係決定水質站址，然需透過多次試誤程序才能決定具最佳水質保護效能的解。一整數規劃優選模式因而被提出，以最小化偵測前總污染水量為目標決策監測站址，並建立另兩個替代線性規劃模式提供更多的決策資訊，以有效監測管網可能產生的損壞污染。 管網損壞分析決策支援系統整合各項損壞分析、停水分析與制水閥損壞擴張樹分析模組，以判別較不可靠的管網區位，提升損壞維修效率。亦發展整合一基於連通性的制水閥關鍵性分析模組，根據鄰接制水閥分區的損壞擴張影響平均量，決定制水閥的連通關鍵性，以更快速提供初步的決策資訊。 所發展的各項優選決策模式與分析管理系統，已以一些管網案例確認其合理性與適用性，可在合理的時間內得到較佳的決策結果。所發展的各項模式與工具亦有助於研擬適當的維護管理策略，相信可供國內自來水管網管理參考及用以提升供水品質。

Water distribution networks (WDNs) should supply safe, stable, and high quality water to consumers. During the distribution, pipeline breaks in a WDN could deteriorate the water quality, cause insufficient water pressure at demand nodes, and subsequently reduce its ability to deliver water. Therefore, vulnerability analysis should be implemented to determine proper maintenance strategies, such as pipeline replacement, remedial actions for a pipe break, and installation of a water quality monitoring network, to improve the performance of a WDN. This study used the valve-enclosed segment as the basic unit to simplify a complex WDN and proposed two depth-first search based algorithms to efficiently identify segments and the critical segments that can shut off water supply to downstream segments when closed. Two failure analysis procedures based on the connectivity among segments and the hydraulic simulation procedure with consideration of insufficient pressure at demand nodes were implemented to evaluate the impact of a failure event for determining proper maintenance strategies. The failure analysis procedures were then applied to simulate the shortage impact caused by shutting off one or more segments, and the results were used to determine effective pipe replacement decisions by a previously developed optimization model. The valve-enclosed segment was also treated as a basic unit for developing the analysis procedure to evaluate the valve criticality, with consideration of the potential shortage impact expansion caused by a failed valve. A search algorithm was developed to identify all possible failure paths which might reach the failed valve. The criticality of a valve is determined based on the summation of potential shortage impacts multiplied by their failure probabilities for all possible failure paths. The valve criticality information can be used to develop an efficient valve maintenance plan. A monitoring network is essential to ensure the quality of water in a WDN. To avoid the tedious trial-and-error procedure proposed in a previous study, a mixed-integer programming model was developed in this study to determine an optimal monitoring network directly. Two additional alternative models were also proposed to provide extra information for making a good decision. A web-based decision support system was developed based on the proposed WDN vulnerability and maintenance analysis procedure and models. Vulnerability analysis related modules, a shut-off analysis module, and a valve failure impact expansion tree analysis module were developed and integrated into the system to facilitate related decision analyses. A connectivity based method was also proposed to define the criticality of a value according to the potential impact expansion of a valve failure. The proposed vulnerability analysis procedure and maintenance models were applied to several WDNs for evaluating and demonstrating their applicability. The results show that the proposed procedures and models could effectively facilitate related decision analyses.