Operation Of Water Distribution Networks Research Articles

An angle-based leak detection method using pressure sensors in water distribution networks

Abstract Leak detection has significant implications for the long-term stable operation of water distribution networks (WDNs). This study presented a novel leak detection method by calculating the angular variance between a pressure vector and other vectors in the database, to evaluate the presence of an anomaly in a network. The top priority for this method was to establish a reliable dataset collected from the pressure sensors, which is generated by EPANET 2.2. Numerous node water demand data in normal conditions were generated by the Monte Carlo method, and leak conditions with various leak flows were simulated by creating leak holes in the pipes. Through learning the composite normal and abnormal data in a certain proportion, the angle-based outlier detection model was employed to identify abnormal events. This angle-based method was applied in an actual WDN and the identification performance for anomalies was compared with that of previous detection methods. The results indicated that the novel method proposed in this study could significantly improve the accuracy and efficiency of leak detection compared to the threshold-based and distance-based detection methods.

Computational Model of Water Distribution Network Life Cycle Deterioration

Water distribution networks (WDNs) have a long life cycle, and understanding how infrastructure deteriorates over time can contribute to its efficient management. In this paper, a computational model is developed to simulate the deterioration of a WDN over its life cycle and analyze how its operation is affected, both hydraulically and economically. For this, four parameters are considered, changing over a 20-year life cycle: (1) an increase in water consumption due to population growth, modeled using statistical growth rates; (2) the deterioration of pipes, which increases according to a constant growth rate of internal roughness; (3) a change in leakage in the network, calculated based on population size, network length, and operating pressure; and (4) the deterioration of pumps, estimated according to their mechanical aging. The results point to maintenance services being essential for the efficient operation of WDNs, with leaks having the greatest impact on operating costs.

Continuous and discrete operation of water distribution networks

Continuous and discrete operation of water distribution networks

A Novel Approach to Avoiding Technically Unfeasible Solutions in the Pump Scheduling Problem

Optimizing pump operation in water networks can effectively reduce the cost of energy. To this end, the literature provides many methodologies, generally based on an optimization problem, that provide the optimal operation of the pumps. However, a persistent shortcoming in the literature is the lack of further analysis to assess if the obtained solutions are feasible from the technical point of view. This paper first showed that some of these available methodologies identify solutions that are technically unfeasible because they induce tank overflow or continuous pump switching, and consequently, proposed a novel approach to avoiding such unfeasible solutions. This consisted in comparing the number of time-steps performed by the hydraulic simulator with the predicted value, calculated as the ratio between the simulation duration and the hydraulic time-step. Finally, we developed a new model which couples Epanet 2.0 with Pikaia Genetic Algorithm using the energy cost as an objective function. The proposed method, being easily exportable into existing methodologies to overcome the limitations thereof, thus represents a substantial contribution to the field of pump scheduling for optimal operation of water distribution networks. The new method, tested on two case studies in the literature, proved its reliability in both cases, returning technically feasible solutions.

Energy and Hydraulic Efficiency in Intermittent Operation of Water Distribution Networks

Energy and Hydraulic Efficiency in Intermittent Operation of Water Distribution Networks

Quality zones automatically identified in water distribution networks by applying data clustering methods to conductivity measurements

This paper presents a clustering study showing how conductivity measured every five minutes by 215 probes over four years can be used to determine specific quality zones for a large Water Distribution Network (WDN): 8500 km of pipes, 4.6 M customers. Conductivity time-series are compared using Dynamic Time Warping. Then, probes are ordered using a density-based method, and probe clusters are extracted automatically. The clusters are a sound representation of water quality in the WDN, both in terms of water origin and water residence time. More specifically, zones directly impacted by plants or by external water imports, mixing zones and zones influenced by tanks, can be isolated and analyzed. Globally, 82% of the probes were found to be clustered, consistent with expert knowledge on the WDN operation; 13% were unclassified; 3% were erroneously clustered; and 1% seemed to be reasonably clustered, without any physical understanding yet. Besides providing users with an increased understanding of water quality in WDNs, conductivity-based clusters offer an interesting prior tool for contamination warning systems.

Methodology for Determining the Maximum Potentially Recoverable Energy in Water Distribution Networks

The excess pressure available in water distribution networks (WDNs) is a relevant aspect in the management and appropriate handling of water resources. If a WDN meets the minimum performance criteria (minimum pressure and maximum flow), excess pressure can occur throughout the day, which is usually lost. These excesses could be considered as potentially recoverable energy (PRE). One way of taking advantage of this energy is to find the nodes on the network where this excess pressure is evident and try to analyze the possible amount of PRE. This work presents a methodology to determine the maximum PRE in a WDN. This methodology includes the locations of the points where the installation of recovery devices leads to this maximum PRE. The method is based on reducing pressures but maintaining circulating points through the lines. Additionally, a new energy balance that allows visualizing and breaking down in more detail all the energy found in a WDN is proposed. The analysis is carried out in an extended period considering different feeding points either by gravity or pumping. Finally, a network resilience index called the Potentially Recoverable Energy Index (PREI) in WDNs is proposed, with which it is possible to diagnose and determine how much energy could be recovered from the network. Study cases presented demonstrate the effectiveness of the methodology and will allow the development of optimizations in the operation of WDNs in favor of the good management of water and energy resources.

A multi-objective optimization model for operation of intermittent water distribution networks

Abstract Intermittent operation of water distribution networks (WDNs) is an undesirable yet inevitable strategy under some circumstances such as droughts, development, electricity blackouts, and water pollution, mostly in developing countries. Intermittent utilization of WDNs poses several disadvantages encompassing water quality degradation, deterioration of the water-distribution system, and extra operational and maintenance costs due to frequently interrupted supply, unfair water distribution among consumers, and reduction of system serviceability. This paper proposes a multi-objective optimization model to address the negative consequences of intermittent water shortages. The model is intended to maximize the quantitative and qualitative reliability and the fairness in water supply, and to minimize the frequency of supply interruption. The developed model also considers pragmatic limitations, water quality, water pressure, and supply reservoir's constraints to plan the operation of intermittent water distribution systems under water shortage. The model's efficiency is tested with a WDN in Iran and compared with a standard operation policy (SOP) for water distribution. According to the evaluated efficiency criteria concerning reliability, resiliency, and vulnerability of water quality and quantity of water supply, the developed model is superior to the SOP rule and improves the performance of the network under intermittent operation. In addition, the results demonstrate there is a tradeoff between the uniformity of water distribution and the frequency of supply interruption that shows operators’ and customers’ conflicting priorities.

Assessment of Failure Modes Caused by Water Hammer and Investigation of Convenient Control Measures

AbstractEconomic and efficient transient control measures are always required to ensure safe and performant operation of water distribution networks (WDNs). This study presents extensive numerical ...

Economic nonlinear predictive control of water distribution networks based on surrogate modeling and automatic clustering

The operation of large-scale water distribution networks (WDNs) is a complex control task due to the size of the problem, the need to consider key operational, quality and safety-related constraints as well as because of the presence of uncertainties. An efficient operation of WDNs can lead to considerable reduction in the energy used to distribute the required amounts of water, leading to significant economic savings. Many model predictive control (MPC) schemes have been proposed in the literature to tackle this control problem. However, finding a control-oriented model that can be used in an optimization framework, which captures nonlinear behavior of the water network and is of a manageable size is a very important challenge faced in practice. We propose the use of a data-based automatic clustering method that clusters similar nodes of the network to reduce the model size and then learn a deep-learning based model of the clustered network. The learned model is used within an economic nonlinear MPC framework. The proposed method leads to a flexible scheme for economic robust nonlinear MPC of large WDNs that can be solved in real time, leads to significant energy savings and is robust to uncertain water demands. The potential of the proposed approach is illustrated by simulation results of a benchmark WDN model.

Robust Scheduling of Water Distribution Networks

Optimal operation of water distribution networks can be posed as a scheduling problem where the objective is to meet the time varying demand while meeting constraints on supply, pressure etc. In the present work, we propose a robust optimization problem to address uncertainty in the parameters of the model used for optimization. The resulting problem is a second order cone program that can be solved efficiently. The formulation ensures a high probability of meeting the demands, adding to the practical significance. Further, we provide the results of applying this technique on a laboratory scale water distribution network.

Optimum Reliable Operation of Water Distribution Network Considering Pumping Station and Tank

This research aims to optimize the operation of pumping stations in water distribution networks (WDNs). Two main objectives are considered: minimizing the pumping energy costs through the scheduling of pumping stations by means of variable-speed pumps and, maximizing the reliability of pumping stations or storage tanks. Accordingly, a multi-objective ant colony optimization is developed in Visual Studio C ++. This optimization algorithm is directly linked to EPANET2.0 for two case studies including Anytown and two loops WDNs. This study reveals that there is a strong correlation between the number of nodes and pumps, and the range of the hydraulic reliability in the solutions of pareto-optimal front. In scheduling of pumping station operation, a wider range of reliability can be provided in storage tanks compared to pumping stations. Based on WDN’s requirements, decision makers can choose a solution with the desired reliability of pumping stations and storage tanks and the relevant pumping energy costs.

Optimal operation of water distribution networks with intermediate storage facilities

The nexus between water and energy reveals that transporting water for end use is a highly energy intensive operation. In this work we consider the optimal operation of a water distribution network consisting of pumps delivering water to different reservoirs, with each reservoir catering to a time varying demand. Pumps and ON/OFF valves are used as manipulated variables to minimize energy consumption while meeting the demand. Due to the nonlinear nature of the pump operating curve and the hydraulics, this results in a Mixed Integer Nonlinear Program (MINLP). We propose a three step decomposition approach to solve this problem efficiently. The applicability of this technique is demonstrated on a water network proposed for a municipality in India and the potential advantages are reported. We also compare the solution times required for the proposed technique and a standard solver and demonstrate the efficiency of the proposed approach.

Development and Applications of K-NRisk for Pressure Dependent Demand Analysis in Water Distribution Networks

Hydraulic analysis of water distribution networks is important not only for the assessment current status, but also for the near and far future prediction with uncertainties. Hydraulic analysis models can be classified into demand driven analysis (DDA) and pressure driven analysis (PDA) depending on nodal outflow assumption. However, the EPANET2, which is globally used model, does not include PDA module, and therefore hydraulic analysis under abnormal conditions is impossible. In this study, a new multi-scenario based hydraulic analysis model for abnormal conditions, K-NRisk is developed by combining PDA technique. The K-NRisk is compared with the existing commercial softwares, and verified by multi-scenario based modeling for typical abnormal conditions. The results show that, the K-NRisk developed in this study can visualize pressure deficient area under abnormal conditions, and also can quantify the water shortage reasonably. Therefore, the K-NRisk can be used as a decision support tool to improve the efficiency of water distribution network operation, to enhance the revenue water ratio at pressure deficient area. Keywords: Water Distribution Networks, Pressure Driven Analysis, K-NRisk, Abnormal Condition Analysis

Discussion of “Optimal Operation of Water Distribution Networks under Water Shortage Considering Water Quality” by Mohammad Solgi, Omid Bozorg-Haddad, Samaneh Seifollahi-Aghmiuni, Parisa Ghasemi-Abiazani, and Hugo A. Loáiciga

Discussion of “Optimal Operation of Water Distribution Networks under Water Shortage Considering Water Quality” by Mohammad Solgi, Omid Bozorg-Haddad, Samaneh Seifollahi-Aghmiuni, Parisa Ghasemi-Abiazani, and Hugo A. Loáiciga

Closure to “Optimal Operation of Water Distribution Networks under Water Shortage Considering Water Quality” by Mohammad Solgi, Omid Bozorg-Haddad, Samaneh Seifollahi-Aghmiuni, Parisa Ghasemi-Abiazani, and Hugo A. Loáiciga

Closure to “Optimal Operation of Water Distribution Networks under Water Shortage Considering Water Quality” by Mohammad Solgi, Omid Bozorg-Haddad, Samaneh Seifollahi-Aghmiuni, Parisa Ghasemi-Abiazani, and Hugo A. Loáiciga

Optimal Management of Barcelona Water Distribution Network using Non-linear Model Predictive Control * *This work has been partially funded by the European Union through the project EFFINET (ref. FP7-ICT-2011-8-318556), by the Spanish Government and FEDER through the projects CI-CYT ECOCIS (ref. DPI2013-48243-C2-1-R), CICYT DEOCS (ref. DPI2016-76493-C3-3-R) and CICYT HARCRICS (ref. DPI2014-58104-R).

Abstract This paper presents a non-linear optimal control strategy for the operational management of water distribution networks (WDNs) including both flow and hydraulic head/pressure constraints. The optimal operation of WDNs should guarantee water supply with suitable pressures at all the demand nodes in the network. The challenge for non-linear model predictive control in this context is to compute control strategies for the pumps and valves in a WDN to supply the required demand while optimizing performance goals related to cost and safety. A two-layer scheme is used in order to produce set-points that can be directly sent to the actuators: on-off schedules for pumps and pressure set-points for pressures reducing valves. Finally, the results of applying the proposed control strategy to a portion of the Barcelona real WDN are provided.

Development and application of the anarchic society algorithm (ASO) to the optimal operation of water distribution networks

Abstract Optimizing the design and operation of urban water distribution networks (WDNs) is a complex, nonlinear problem. The optimization of WDNs can be performed for the pumping schedule, the location and elevation of reservoirs, the physical characteristics of pipes, and the placement of pressure-reducing valves, among other objectives. This study applies the anarchic society optimization (ASO) algorithm to find the optimal location and elevation of auxiliary tanks in urban water networks. The ASO is validated with mathematical benchmark functions, and is implemented to determine the location and elevation of auxiliary tanks in two urban water networks. The fuzzy reliability index for urban water network ranges between 74 and 79%, which is close to the global optima. The ASO exhibited better performance optimizing the reliability of WDNs than the genetic algorithm.

Analysis Model of Physical Leakage Flow Based on Blind Source Separation Theory

A new physical leakage flow analysis model is established based on blind source separation theory (BSS). The model simultaneously considers the correlation and uncertainty between water consumption and physical leakage flow, takes constraints independent component analysis (CICA) algorithm in BSS, respectively establishes reference vector of water consumption and physical leakage flow to obtain the waveform information of physical leakage flow. The standard deviation and mean of the two flows are respectively calculated based on water balance analysis report and minimum night flow, to achieve the amplitude reduction of physical leakage flow. This analysis model is the application of the high-order statistical information of water distribution network operation data with high simulation accuracy.

Optimal Operation of Water Distribution Networks under Water Shortage Considering Water Quality

AbstractWater shortages are caused by hydrological droughts and by the disruption of the operation of water distribution networks (WDNs). The water pressure and residual chlorine concentration are examples of quantitative and qualitative indexes, respectively, of a WDN’s performance. This work considers quality and quantity variables simultaneously in the operation of WDNs under water shortages. An optimization model is developed to find the optimum water allocation schedule in WDNs. The objectives of the optimization model are maximizing the number of node-times in which the chlorine concentration is in the allowable range, and maximizing the number of supply nodes under desirable pressure. These objectives satisfy the principle of justice in water distribution under water shortage. The optimization model was solved for a real WDN under different scenarios using the honey-bee mating optimization (HBMO) algorithm linked to a hydraulic simulator. The performance of the developed model was compared to an op...