Leak localization in water distribution networks using pressure and data-driven classifier approach

Leaks in water distribution networks (WDNs) are one of the main reasons for water loss during fluid transportation. Considering the worldwide problem of water scarcity, added to the challenges that a growing population brings, minimizing water losses through leak detection and localization, timely and efficiently using advanced techniques is an urgent humanitarian need. There are numerous methods being used to localize water leaks in WDNs through constructing hydraulic models or analyzing flow/pressure deviations between the observed data and the estimated values. However, from the application perspective, it is very practical to implement an approach which does not rely too much on measurements and complex models with reasonable computation demand. Under this context, this paper presents a novel method for leak localization which uses a data-driven approach based on limit pressure measurements in WDNs with two stages included: (1) Two different machine learning classifiers based on linear discriminant analysis (LDA) and neural networks (NNET) are developed to determine the probabilities of each node having a leak inside a WDN; (2) Bayesian temporal reasoning is applied afterwards to rescale the probabilities of each possible leak location at each time step after a leak is detected, with the aim of improving the localization accuracy. As an initial illustration, the hypothetical benchmark Hanoi district metered area (DMA) is used as the case study to test the performance of the proposed approach. Using the fitting accuracy and average topological distance (ATD) as performance indicators, the preliminary results reaches more than 80% accuracy in the best cases.Peer ReviewedPostprint (published version

Two-layer scheduling scheme for pump stations

Trabajo presentado a la IEEE Conference on Control Applications (CCA) celebrada en Juan-les-Pins, Antibes (Francia) del 8 al 10 de octubre de 2014.In this paper, a two-layer scheduling scheme for pump stations in a water distribution network has been proposed. The upper layer, which works in one-hour sampling time, uses Model Predictive Control (MPC) to produce continuous flow set-points for the lower layer. While in the lower layer, a scheduling algorithm has been used to translate the continuous flow set-points to a discrete (ON-OFF) control operation sequence of the pump stations with the constraints that pump stations should draw the same amount of water as the continuous flow set-points provided by the upper layer. The tuning parameters of such algorithm are the lower layer control sampling period and the number of parallel pumps in the pump station. The proposed method has been tested in the Richmond case study.This work has been funded by the Spanish Ministry of Science and Technology through the project CYCYT WATMAN DPI2009-13744 and also funded by EFFINET grant FP7-ICT-2012-318556 of the European Commission.Peer Reviewe

Coordinating model predictive control of transport and supply water systems

Transport and supply water networks are two types of systems which have received a significant amount of attention in the recent years. Issues on how to obtain the best performance for a given transport or supply water systems, or how to coordinate interactions between them are still open and need more research. This chapter presents a hierarchical Model Predictive Control (MPC) scheme with a supervisor that coordinates transport and supply water systems. First, a two-level hierarchical control structure resulting from a functional decomposition of water network is briefly presented. Inside each hierarchy, an MPC controller is used. In the two-level hierarchy, a supervisory coordinating mechanism is used to generate control strategies which consider objectives at different time scales. The first level, in charge of managing the transport system, works in a daily scale in order to achieve the global management policies for the transport over water (e.g., navigation, vessels and barges) in different rivers and balance management of different reservoirs. The second level, in charge of managing the supply system, works in a hourly scale and manipulates actuator (pumps and valves) set-point to satisfy the local water supplying objectives (e.g., minimizing economic cost, handling emergency storage and smoothing actuator operation). The results of the modeling will be applied to the Catalunya Regional Water Network and based on an aggregate model.This research has been partially funded by CDTI (MCyT) project HIDROPTIM IDI-20100722, the DGR of Generalitat de Catalunya (SAC group Ref. 2009/SGR/1491), the AGAUR by an FI grant and by EFFINET grant FP7-ICT-2012-318556 of the European Commission.Peer Reviewe

Combining CSP and MPC for the operational control of water networks

This paper presents a control scheme which uses a combination of linear Model Predictive Control (MPC) and a Constraint Satisfaction Problem (CSP) to solve the non-linear operational optimal control of Drinking Water Networks (DWNs). The methodology has been divided into two functional layers: first, a CSP algorithm is used to transfer non-linear DWNs pressure equations into linear constraints on flows and tank volumes, which can enclose the feasible solution set of the hydraulic non-linear problem during the optimization process. Then, a linear MPC with tightened constraints produced in the CSP layer is solved to generate control strategies which optimize the control objectives. The proposed approach is simulated using Epanet to represent the real DWNs. Non-linear MPC is used for validation. To illustrate the performance of the proposed approach, a case study based on the Richmond water network is used and a realistic example, D-Town benchmark network, is added as a supplementary case study.This research has been partially funded by the Spanish project “ECOCIS: Economic Operation of Critical Infrastructure Systems” (reference DPI-2013-48243-C2-1-R) and EFFINET Grant (FP7-ICT-2012-318556) of the European Commission.Peer Reviewe

Combining CSP and MPC for the operational control of water networks: Application to the Richmond case study

Trabajo presentado al 19th IFAC World Congress celebrado del 24 al 29 de agosto de 2014 en Cape Town (Sudafrica).This paper presents the combination of Linear Model Predictive Control (MPC) with Constraints Satisfaction Problem (CSP) for the operational control of drinking water networks. The methodology has been divided into two functional layers: First, a CSP algorithm is used to transfer nonlinear pressure equations of drinking water networks (DWNs) into linear constraints, which can enclose feasible solution of the hydraulic non-linear problem during the optimizing process. Then, a linear MPC with added linear constraints is solved. Finally, the proposed approach is simulated using Epanet to represent the real DWNs. PLIO, which is a generic operational tool for controlling water network that uses non-linear MPC, is used for validation. The classical Richmond water system is used as a case study.This research has been partially funded by the DGR of Generalitat de Catalunya (SAC group Ref. 2009/SGR/1491), Doctorat Industrial 2013-DI-041 and by EFFINET.Peer Reviewe

Temporal multi-level coordination techniques oriented to regional water networks: Application to the Catalunya case study

In this paper, a multi-layer model predictive control (MPC) with temporal multi-level coordination for regional water supply systems is proposed. First, a multi-layer control structure resulting from a functional decomposition of water network is briefly presented. Inside each layer, an MPC based controller is used. Between related layers, a temporal multi-level coordination mechanism is used to generate control strategies which consider objectives and time scales of both layers. The upper layer which is named supply layer works in a daily scale in order to achieve the global management policies for the different reservoirs. The lower layer which is named transportation layer works in an hourly scale and is in charge of manipulating the actuators (pumps and valves) set-point to satisfy the local objectives. The results of the modelling will be applied to the Catalunya Regional Water Network and this paper presents the simulation results based on an aggregate model of this network.This research has been partially funded by CDTI (MCyT) project HIDROPTIM IDI-20100722, the DGR of Generalitat de Catalunya (SAC group Ref. 2009/SGR/1491), the AGAUR by an FI grant and by EFFINET grant FP7-ICT-2012-318556 of the European Commission.Peer Reviewe

Integrated simulation and optimization scheme of real-time large-scale water supply network: applied to Catalunya case study

This paper presents an integrated simulation and optimization modeling approach in order to provide the optimal configuration for large-scale water supply systems (LSWSS) in real time. Model predictive control (MPC) has been chosen to handle the complex set of objectives involved in the management of LSWSS. The computation of control strategies by MPC uses a simplified model of the network dynamics. The use of the combined approach of optimization and simulation contributes to making sure that the effect of more complex dynamics, better represented by the simulation model, may be taken into account. Coordination between simulator and optimizer works in a feedback scheme, from which both real-time interaction and extensive validation of the proposed solution have been realized using a case study based on the Catalunya regional water network.This research has been partially funded by by Project ECOCIS DPI2013-48243-C2-1-R of Spanish Ministry of Education and by EFFINET grant FP7- ICT-2012-318556 of the European Commission.Peer Reviewe

Advanced integrated real-time control of combined Urban drainage systems using MPC

Combined urban drainage system (CUDS) collect both wastewater and raining water through sewer networks to wastewater treatment plants (WWTP) before releasing to the environment. During storm weather, rain and wastewater can overload the capacity of the CUDS and/or the WWTPs, producing combined sewer overflows (CSO). In order to improve the management efficiency of CUDS, advanced real-time control (RTC) of detention and diversion infrastructures in the sewer systems has been proven to contribute to reducing the CSO volumes. This work considers the integrated RTC of sewer network and WWTPs based on model predictive control (MPC) and taking into account the water quality as well as quantity, with the objective of minimizing the environmental impact of CSO on receiving waters. The control approach is validated using a real pilot Badalona sewer network in Spain. The first results, discussion and conclusions are also provided.Peer ReviewedPostprint (author's final draft

An ab-initio study of circular photogalvanic effect in chiral multifold semimetals

So far, the circular photogalvanic effect (CPGE) is the only possible quantized signal in Weyl semimetals. With inversion and mirror symmetries broken, Weyl and multifold fermions in band structures with opposite chiralities can stay at different energies and generate a net topological charge. Such kind of net topological charge can present as a quantized signal in the circular polarized light induced injection current. According to current theoretical understanding, RhSi and its counterparts are believed to be the most promising candidate for the experimental observation of the quantized CPGE. However, the real quantized signal was not experimentally observed to date. Since all the previous theoretical studies for the quantized CPGE were based on effective model but not realistic band structures, it should lose some crucial details that influence the quantized signal. The current status motives us to perform a realistic ab-initio study for the CPGE. Our result shows that the quantized value is very easy to be interfered by trivial bands related optic transitions, and an fine tuning of the chemical potential by doping is essential for the observation of quantized CPGE. This work performs the first ab-initio analysis for the quantized CPGE based on realistic electronic band structure and provides an effective way to solve the current problem for given materials.Comment: 7 pages, 5 figure