Optimal Design of Isolation Valve System for Water Distribution Networks

This paper presents a novel methodology for assessing an isolation valve system and the portions of a water distribution network (segments) directly isolated by valve closure. Planned (e.g. regular maintenance) and unplanned interruptions (e.g. pipe burst) occur regularly in water distribution networks making it necessary to isolate pipes. To isolate a pipe in the network, it is necessary to close a subset of valves which directly isolate a small portion of the network, i.e., causing minimum possible disruption. This is not always straightforward to achieve as the valve system is not normally conceived for isolating each pipe separately (i.e. locating two valves at the end of each pipe). Therefore, for management purposes, it is important to identify the association between each subset of valves and the segments directly isolated by closing them. This is also important to improve the design of the isolation valve system in order to increase network reliability. Thus, this paper describes an algorithm for identifying the association between valves and isolated segments. The approach is based on the use of topological matrices of a network whose topology is modified in order to account for the existence of the valve system. The algorithm is tested on an Apulian network where the isolation valve system is designed using a classical multi-objective genetic algorithm as an optimizer.