Optimizing drinking water distribution system operations

Sustainability

The problem of scheduling pumps is widely discussed in the literature in the context of improving energy efficiency, production costs, emissions, and reliability. In some studies, the authors analyze the available case studies and compare the results; others present their own computational methods. In the paper, a problem of pump scheduling in regular everyday operations of a water supply operator is considered. The issues of water production optimization and energy savings are part of the topic of sustainable development. The objective of the article is the minimization of the cost of electric power used by the pumps supplying water. It is achieved thanks to the variability of both the demand for water and the price of electric power during the day combined with the possibility of storing water. The formulation of an existing electric power cost optimization problem as a binary linear programming problem was improved. An essential extension of the above mathematical model, which en...

2022

A significant portion of the operating costs associated with drinking water distribution networks is related to energy usage, which is mostly employed to drive pumps. One strategy to improve energy efficiency and to reduce energy cost is to operate water pumps in an optimal manner that allows a reduction in energy consumption. This produces also environmental benefits, since decreasing energy consumption contributes to the reduction of the associated greenhouse gas emissions, helping utility providers to reduce their carbon footprint and to reach sustainability goals. However, numerical optimization of water distribution network operation is a difficult problem to solve, given the combination of nonlinear hydraulic dynamics and the presence of discrete decision variables, corresponding to pumps and valves having on/off or open/closed characteristics. In this work, we address such problem from an industrial perspective, reformulating the mathematical program that is at the core of such operation optimization solutions using complementarity constraints to transform the resulting mixed integer nonlinear program into a nonlinear program having only continuous variables. This allow us to obtain a tractable optimization problem, that could be solved in a short amount of time even for large-scale water networks, making it compatible with industrial implementation and real-time optimization.

Journal of the American Water Resources Association, 1985

Efficient operation of a city water supply system is an important goal of a l l municipalities. Efficient operation should result in minimum operation cost through reduction in total energy use and/ or reduction in on-peak energy consumption. An optimization model was designed for operating the water supply systems of cities using groundwater. The Newton-Raphson pipe network was used for network analysis and a dynamic programming optimization algorithm was used for determining a schedule for pump operation in the pipe network system. The model is most suitable for use in small cities with up to 45,000 in population, but with large-scale disintegration techniques may also be used for larger cities. The savings in operation costs are a function of energy cost and energy use pattern and water use pattern in the area. (KEY TERMS: groundwater; urban water supply; energy use; dynamic programming; pipe network analysis.) 1. The water surface level in the wells. 2. The characteristics of the pipe network, such as roughness, diameter, length, and design.

Sādhanā

The design of rural drinking water schemes consists of optimization of several network components like pipes, tanks, pumps and valves. The sizing and configuration of these network configurations need to be such that the water requirements are met while at the same time being cost efficient so as to be within government norms. We developed the JalTantra system to design such water distribution networks. The Integer Linear Program (ILP) model used in JalTantra and described in our previous work solved the problem optimally, but took a significant amount of time for larger networks-an hour for a network with 100 nodes. In this current work, we describe a series of three improvements of the model. We prove that these improvements result in tighter models, i.e. the set of points of linear relaxation is strictly smaller than the linear relaxation for the initial model. We test the series of three improved models along with the initial model over eight networks of various sizes and show a distinct improvement in performance. The 100-node network now takes only 49 s to solve. These changes have been implemented in JalTantra, resulting in a system that can solve the optimization of real world rural drinking water networks in a matter of seconds. The JalTantra system is free for use, and is available at https://www.cse.iitb.ac.in/jaltantra/.

International Transactions in Operational Research, 2020

The problem addressed in this paper focuses on the reduction of electrical energy costs for the operation of hydraulic pumps, which are used for catchment and distribution of water in water supply systems. As the electricity tariffs are different according to the time of day, it is necessary to decide when and how many pumps must be used to collect and distribute water, in each period of time, and, when there must be water transfer among tanks so that the demand of each consumer center is met without a lack of resources. A mixed integer programming (MIP) model is proposed and a competitive MIP-based heuristic is developed to solve this problem. Numerical tests in a case study carried out with the water supply system of a Brazilian city demonstrate the efficiency of the proposed mathematical model and solution method.

The operation of a water distribution system is a complex task which involves scheduling of pumps, regulating water levels of storages, and providing satisfactory water quality to customers at required flow and pressure. Pump scheduling is one of the most important tasks of the operation of a water distribution system as it represents the major part of its operating costs. In this paper, a novel approach for modeling of explicit pump scheduling to minimize energy consumption by pumps is introduced which uses the pump start/end run times as continuous variables, and binary integer variables to describe the pump status at the beginning of the scheduling period. This is different from other approaches where binary integer variables for each hour are typically used, which is considered very impractical from an operational perspective. The problem is formulated as a mixed integer nonlinear programming problem, and a new algorithm is developed for its solution. This algorithm is based on the combination of the grid search with the Hooke-Jeeves pattern search method. The performance of the algorithm is evaluated using literature test problems applying the hydraulic simulation model EPANet.

Numerical tools for the optimization of several aspects of drinking water distribution networks have been around for some time now and are widely discussed in the scientific literature. However, their successful practical application remains a challenge, especially when combining multiple objectives and operational boundary conditions. In this contribution, we describe a number of optimization cases, including the optimization approaches applied. We discuss the technical and practical challenges that are faced when applying numerical optimization techniques to real world problems of water utilities.

Proceedings of the ICE - Water Management, 2013

This paper aims to assess the reduction in level of leakage and excess pressure in water distribution networks (WDNs) after imposing a schedule to a pumping station. This is of particular importance where managers, due to financial considerations, may be forced to construct WDNs that are directly connected to water resources. In such WDNs there is no tank, leading to unreasonable water loss and excess pressure in the WDN. Also, in such circumstances, the size of the search space is reduced so that no need is felt to use optimisation algorithms to find the optimal pumping schedule. In this study, the pumping schedule was obtained for two real WDNs in Iran, using single-speed pumps and variable-speed pumps. The results showed that through smart scheduling energy cost savings can be up to 24%, and the existing leakage and excess pressure can be reduced by 11% and 53%, respectively. It was noted that an increase in the number of pumps could improve the amount of savings made. Water Management Scheduling and operating costs in water distribution networks Hashemi, Tabesh and Ataeekia Offprint provided courtesy of www.icevirtuallibrary.com Author copy for personal use, not for distribution original PPC. Equation 3 shows that pumping energy consumption is directly affected by the pumping head.

Journal of Water Resources Planning and Management, 1989

Optimal operation of a water supply system is solved by progressive optimality (PO), an iterative dynamic programming (DP) method. Given the forecasted demands for the coming 24 hr, the initial and final conditions in the reservoirs, the hydraulic properties of all system components, and the variable energy cost over the day, an optimal schedule of pump operation is found. The algorithm cycles iteratively over the time steps (hours of the day) and network subsystems, and converges to the optimum from any (feasible or infeasible) initial solution. The global optimum is guaranteed only under certain conditions; otherwise a local optimum may be reached. The method is developed and demonstrated on a regional water supply system with eight reservoirs and seven pumping stations. 'Head, Dept. of Real-Time Control for Water Systems, Texel Electronics, 37 Petach Tikva Rd.

Mathematics in Applied Sciences and Engineering

Water is a basic part of our daily lives, as such effective water supply is of paramount importance. Thus, as a result of the rise in population size and water shortage there is the need for proper, suitable and optimal utilization of water resources to efficiently be distributed among the populace. The proper allocation and distribution of water in the field of network planning need to be modelled through mathematical parameters for objective of water distribution system. This mathematical approach requires of solving an optimization problem based on multi-objective function subjected to certain constraints of mixed integer linear programming objective function which is proportional to the cost of the water distribution network. This study present a conceptual model of multi-objective optimization proposed for determination of design parameters of water distribution system by considering the significant number of constraints, decision variables, cost and reliability objective funct...