Reliability-based design of water distribution networks considering mechanical failures

For effective design of Water Distribution Networks (WDNs), it is necessary to consider the reliability of the system subject to mechanical and hydraulic failures. In this paper, a reliability based framework is presented for design of WDNs using self-adaptive differential evolution (SaDE) algorithm. The framework includes three main components:a simulation model, a reliability assessment model and an optimization model. Simulation model uses EPANET toolkit for simulation of flows and pressure distribution in pipe network, and its outputs are used in reliability assessment model to determine the minimum cut sets. Reliability assessment model consists of determination of system and nodal reliabilities based on minimum cut sets. The reliability is estimated in terms of demand satisfaction subject to the mechanical failure of components. The optimization model finds optimal pipe diameters considering minimization of network cost as objective subject to a minimum level of reliability and other constraints, and the model is solved by using SaDE algorithm. The application of model is illustrated by applying it to a hypothetical WDN consisting of 17 pipes, 13 nodes, a supply source and a pump. On comparison of the results of study with previous studies, it is found that the present framework yields in better solutions and saves significant amount of computational time.