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Title: Water distribution networks with dynamic topology
Author: Wright, Robert John
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2016
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The subdivision of water distribution networks (WDN) into zones, known as district metered areas (DMAs), is a popular approach to leakage management used by water companies. The DMAs are formed by permanently closing isolation valves at the boundaries of each zone (known as boundary valves). By forming discrete zones in the WDN, leakage estimates can be made at night when demand is low, which is used to prioritise pipe repair and replacement programmes. However, the permanent closure of boundary valves has also caused several disadvantages, including reduced network resilience to failure, sub-optimal pressure management, and water quality problems. This thesis introduces a novel approach to the operational management of WDNs, where DMAs are dynamically aggregated for improved network resilience, pressure management and water quality, and segregated for leakage monitoring at night. This is facilitated by replacing closed boundary valves with self-powered, remote control valves (dynamic boundary valves). The operation of a dynamic topology can therefore successfully eliminate the disadvantages of conventional DMAs, whilst retaining or improving their success in leakage monitoring. The investigation is carried out both analytically and experimentally on a real, operational UK network supplying approximately 8,000 properties in order to establish the benefits and challenges of the proposed approach. An extensive review of the current and emerging forms of pressure and DMA management from around the world is carried out. A case study using a real large scale network (3,148km of pipeline) demonstrates the current state of DMAs and their conformity to DMA design guidelines, and identifies how a dynamic DMA topology can improve network performance. A novel resilience index (the Reserve Capacity) is then used in the design of the dynamic DMA topology in the experimental programme. The analytical and experimental investigation has demonstrated a 27% reduction in leakage using a dynamic DMA topology over the most common approach to pressure management, and strong improvements in network resilience to failure where 1,400 customers maintained a supply during a real, major burst incident that would otherwise have been disconnected. In order to actuate near optimal control in the experimental programme, a novel optimisation algorithm based on sequential convex programming (SCP) is proposed for the control of valves. The SCP method takes advantage of computationally efficient solvers that facilitate prompt and reliable convergence. The algorithm also includes the development of a novel, convex valve model that can be integrated into efficient null space algorithms. In order to actuate the control, a novel approach for valve control in DMAs with dynamic topology is proposed, where time varying flow modulation curves are used based on the dynamic connectivity of DMAs.
Supervisor: Stoianov, Ivan ; Parpas, Panos Sponsor: Engineering and Physical Sciences Research Council ; Cla-Val Ltd (Firm)
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral