Burst Detection in Water Distribution Systems via Active Identification Procedure

This paper considers an approach to detect unreported pipe bursts in water distribution systems via active identification procedure. The approach involves carrying out an e-FAVOR test; results of the test are used together with a hydraulic model of the network as the inputs to a software tool, which is under development. New bursts indicators are proposed, which are considered to be more resilient to modelling errors and to inaccurate reading of the pressure logger elevation. The methodology was tested in practice in a manual manner and proved to be effective, but time consuming. In this paper some automatic analysis algorithms, developed to speed up the burst detection process, are described and tested via simulations. Results to date indicate suitability of the proposed burst indicators and the developed algorithms

Bursts Identification in Water Distribution Systems

The leakage reduction problem as a whole is complex and requires co-ordinated actions in different areas of water network management, such as: direct detection and repair of existing bursts, general pipe rehabilitation programmes and operational pressure control. Water companies undertake a mixture of these complimentary actions. General pipe rehabilitation is the most costly and long term action, but is undertaken to improve a number of different factors including leakage and water quality. Operational pressure control is a cost-effective action for reducing leakage over whole sub-networks, and for reducing the risk of further leaks by smoothing pressure variations and is the subject of ongoing research. Detection and repair actions are targeted at sub-networks where bursts are present. Benefits of quick burst repair include reduced water losses, reduced disruption to traffic, reduced consequent losses (e.g. from flooding), and also reduced disruption to customers' supplies, which is an important water industry performance measure. The existing methods typically use passive identification approach whilst the presented approach is based on the active identification procedure. The proposed burst location algorithm is based on comparing data by means of statistical analysis from a simple field experiment with results of water network simulation. An extended network hydraulic simulator is used to model pressure dependent leakage terms. The presence of a burst changes the flow pattern and also pressure at network nodes, which may be used to estimate the burst size and its location. The influence of such random factors as demand flows and background leakage on the process of burst detection is also considered. The field experiment is an extended fixed and variable orifice (e-FAVOR) test. During this test inlet pressure is being stepped up and down and the following variables are measured: inlet flow, inlet pressure (head) and pressure at a number of selected sensitive nodes. The method consists of three stages and uses two different models; one is inlet flow model (IFM) to represent the total inlet flow and another is the extended hydraulic model to simulate different burst locations. Initially the presence of a potential burst is investigated. If this is confirmed values of the demand, background leakage flow and burst flow in IFM are subsequently estimated. These are used to identify the burst site at the third stage of the method. The approach has been validated by solving a practical case study with correct diagnosis of the existing problems

Pump schedules optimisation with pressure aspects in complex large-scale water distribution systems

This paper considers optimisation of pump and valve schedules in complex large-scale water distribution networks (WDN), taking into account pressure aspects such as minimum service pressure and pressuredependent leakage. An optimisation model is automatically generated in the GAMS language from a hydraulic model in the EPANET format and from additional files describing operational constraints, electricity tariffs and pump station configurations. The paper describes in details how each hydraulic component is modelled. To reduce the size of the optimisation problem the full hydraulic model is simplified using module reduction algorithm, while retaining the nonlinear characteristics of the model. Subsequently, a nonlinear programming solver CONOPT is used to solve the optimisation model, which is in the form of Nonlinear Programming with Discontinuous Derivatives (DNLP). The results produced by CONOPT are processed further by heuristic algorithms to generate integer solution. The proposed approached was tested on a large-scale WDN model provided in the EPANET format. The considered WDN included complex structures and interactions between pump stations . Solving of several scenarios considering different horizons, time steps, operational constraints, demand levels and topological changes demonstrated ability of the approach to automatically generate and solve optimisation problems for a variety of requirements

Online Simplification of Water Distribution Network Models

This paper presents an implementation of the simplification algorithm of water distribution network (WDN) models for the purpose of inclusion to the online optimisation strategy for the energy and leakage management in WDN, formulated within a model predictive control framework. The advantage of the online model reduction is adaptation to abnormal situations and structural changes in a network. The implementation was carried out with the utilisation of nowadays parallel programing techniques to distribute the simplification tasks across multiple CPU treads. This resulted in significant reduction of the computational time required for the simplification process of the large–scale WDN models. The authors also highlighted a problem of the energy distribution when the reduced and original models were compared

Modelling and simulation of water distribution systems with quantised state system methods

The work in this paper describes a study of quantised state systems in order to formulate a new framework within which water distribution systems can be modelled and simulated. In contrast to the classic time-slicing simulators, depending on the numerical integration algorithms, the quantisation of system states would allow accounting for the iscontinuities exhibited by control elements in a more efficient manner, and thereby, offer a significant increase in speed of the simulation of water network models.The proposed approach is evaluated on a case study and compared against the results obtained from the Epanet2 simulator and OpenModelica

Utility-service provision as an example of a complex system

Utility–service provision is a process in which products are transformed by appropriate devices into services satisfying human needs and wants. Utility products required for these transformations are usually delivered to households via separate infrastructures, i.e., real-world networks such as, e.g., electricity grids and water distribution systems. owever, provision of utility products in appropriate quantities does not itself guarantee hat the required services will be delivered because the needs satisfaction task requires not only utility products but also fully functional devices. Utility infrastructures form complex networks and have been analyzed as such using complex network theory. However, little research has been conducted to date on integration of utilities and associated services within one complex network. This paper attempts to fill this gap in knowledge by modelling utility–service provision within a household with a hypergraph in which products and services are represented with nodes whilst devices are hyperedges spanning between them. Since devices usually connect more than two nodes, a standard graph would not suffice to describe utility–service provision problem and therefore a hypergraph was chosen as a more appropriate representation of the system. This paper first aims to investigate the properties of hypergraphs, such as cardinality of nodes, betweenness, degree distribution, etc. Additionally, it shows how these properties can be used while solving and optimizing utility– service provision problem, i.e., constructing a so-called transformation graph. The transformation graph is a standard graph in which nodes represent the devices, storages for products, and services, while edges represent the product or service carriers. Construction of different transformation graphs to a defined utility– service provision problem is presented in the paper to show how the methodology is applied to generate possible solutions to provision of services to households under given local conditions, requirements and constraints

Couch-based motion compensation: modelling, simulation and real-time experiments

Abstract The paper presents a couch-based active motion compensation strategy evaluated in simulation and validated experimentally using both a research and a clinical Elekta Precise Table™. The control strategy combines a Kalman filter to predict the surrogate motion used as a reference by a linear model predictive controller with the control action calculation based on estimated position and velocity feedback provided by an observer as well as predicted couch position and velocity using a linearized state space model. An inversion technique is used to compensate for the dead-zone nonlinearity. New generic couch models are presented and applied to model the Elekta Precise Table™ dynamics and nonlinearities including dead zone. Couch deflection was measured for different manufacturers and found to be up to 25 mm. A feed-forward approach is proposed to compensate for such couch deflection. Simultaneous motion compensation for longitudinal, lateral and vertical motions was evaluated using arbitrary trajectories generated from sensors or loaded from files. Tracking errors were between 0.5 and 2 mm RMS. A dosimetric evaluation of the motion compensation was done using a sinusoidal waveform. No notable differences were observed between films obtained for a fixed- or motion-compensated target. Further dosimetric improvement could be made by combining gating, based on tracking error together with beam on/off time, and PSS compensation.</jats:p

Combined Energy and Pressure Management in Water Distribution Systems

In this paper a method is proposed for combined energy and pressure management via integration and coordination of pump scheduling with pressure control aspects. The proposed solution involves: formulation of an optimisation problem with the cost function being the total cost of water treatment and pumps energy usage, utilisation of an hydraulic model of the network with pressure dependent leakage, and inclusion of a PRV model with the PRV set-points included as a set of decision variables. Such problem formulation led to the optimizer attempting to reduce both energy usage and leakage. The developed algorithm has been integrated into a modelling, simulation and optimisation environment called FINESSE. The case study selected is a major water supply network, being part of Yorkshire Water Services, with a total average demand of 400 l/s

Single infrastructure utility provision to households: Technological feasibility study

This paper contemplates the future of utility infrastructure, and considers whether an “All-in-One” approach could supply all necessary utility services to tomorrow's households. The intention is not to propose infrastructure solutions that are currently technically feasible or justifiable, however; the objective is to present visions of future infrastructure that would only be possible with new advances in science and technology, or significant improvements and adaptations of existing knowledge and techniques. The All-in-One vision is explored using several vignettes, each of which envisions a novel, multi-functional infrastructure for serving future communities. The vignettes were conceived using imaginative exercises and brain-storming activities; each was then rooted in technological and scientific feasibility, as informed by extensive literature searches and the input of domain leaders. The vignettes tell their own stories, and we identify the challenges that would need to be overcome to make these visions into reality. The main aim of this work is to encourage radical approaches to thinking about future infrastructure provision, with a focus on rationalisation, efficiency, sustainability and resilience in preparation for the challenging times ahead. The All-in-One concept introduces the possibility of a unified and singular system for infrastructure service provision; this work seeks to explore the possibility space opened thereby