Water Supply Networks with Dynamically Adaptive Connectivity and Hydraulic Conditions: Design and Control

Abstract

<p>Water utilities around the globe are facing an extraordinary demand for the secure supply of potable water as a result of population growth, urbanisation and climate change. New knowledge, technologies and systems-based approaches are urgently needed to adaptively optimise resource capacity, operations and assets utilisation during a time of escalating environmental, regulatory and financial pressures.<br>This presentation summarises fundamental mathematical and engineering challenges for the design, optimisation and control of next generation water supply networks. These networks dynamically change connectivity (topology), hydraulic conditions and operational objectives. The design and control of dynamically adaptive water supply networks aims to improve pressure management, resilience, efficiency, incident management and sustainability.<br>The current ability of complex water networks to dynamically adapt their connectivity, operational conditions and application objectives is extremely limited. Water supply networks are operated as disjointed (or loosely coupled) sub-systems that have evolved over many years. The operational practice of sub-dividing water supply networks into small discrete areas, District Metered Areas (DMAs), has been successfully implemented by the UK water industry to reduce leakage in excess of 30% in the last 25 years. A DMA has a fixed network topology with permanent boundaries, typically a single inlet and it includes between 1,000 and 3,000 customer connections. By closing boundary valves to form small metered areas, the natural redundancy of connectivity and supply within large looped networks is severely reduced; thus affecting operational resilience, water quality and energy losses. Consequently, the implementation of DMAs has introduced operational constraints that affect both consumers and utilities. Furthermore, these constraints are beginning to inflict financial penalties upon water utilities through recently introduced performance indicators.<br>The dynamically adaptive sectorisation and configurability of water supply networks that we have pioneered combines the benefits of the traditional DMA approach for leakage management with the advantages of substantially improved resilience and considerably enhanced management of pressure, energy, failure incidents and water quality. This operational method includes the replacement of a subset of kept-shut boundary and control valves with self-powered network controllers with varying modulation functions. The controllers modify the network connectivity and continuously monitor and control the hydrodynamic conditions. To enable this new approach, we have been developing novel monitoring, modelling and control methods and technologies. We have been extensively evaluating these in operational networks. <br>In this presentation, we summarise design-for-control strategies to improve the pressure management and resilience of sectorized water distribution networks (WDN). We formulate the mathematical optimization problems and describe solution methods for the resulting large-scale non-linear (NLP) and multi-objective mixed-integer non-linear programs. We also discuss analytical and engineering challenges for the scalable implementation of these methods. </p>