Optimisation of the operation of water distribution systems has been an active research field for almost half a century. It has focused mainly on optimal pump operation to minimise pumping costs and optimal water quality management to ensure that standards at customer nodes are met. This paper provides a systematic review by bringing together over two hundred publications from the past three decades, which are relevant to operational optimisation of water distribution systems, particularly optimal pump operation, valve control and system operation for water quality purposes of both urban drinking and regional multiquality water distribution systems. Uniquely, it also contains substantial and thorough information for over one hundred publications in a tabular form, which lists optimisation models inclusive of objectives, constraints, decision variables, solution methodologies used and other details. Research challenges in terms of simulation models, optimisation model formulation, selection of optimisation method and postprocessing needs have also been identified. A review of operational optimisation of water distribution systems is provided.Future challenges were identified, despite the large body of existing literature.Universally agreed formulation of an operational optimisation problem is needed.Algorithm performance for a particular problem requires improved understanding.A method for selecting only one solution for a real system needs to be developed.

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Lost in optimisation of water distribution systems? A literature review of system operation

Considering water-energy nexus in optimising water supply systems not only ensures the sustainability of the water supply for increasing water demand but also diminishes water-related energy and environmental concerns. This paper presents a review highlighting knowledge gaps in optimisation models related to the water-energy nexus in water supply systems or “water supply side of the nexus”. Studies reported in the literature are categorised and systematically analysed in terms of different energy sources, centralised/ decentralised approaches and system parameters uncertainties. Several major gaps are identified. These include the lack of optimisation models capturing spatial aspects as well as environmental impacts of the nexus problems. The shortage of models considering uncertainties associated with water demand and renewable energy supply is another knowledge gap in this area. However, the main gap is the absence of models for optimising long-term planning of water supply system considering renewable energy within an urban context. Accordingly, based on this review, we have suggested pointers for future studies in the water supply side of the nexus.

The role of water-energy nexus in optimising water supply systems – Review of techniques and approaches

With dynamic electricity pricing, the operation of water distribution systems (WDS) is expected to become more variable. The pumps moving water from reservoirs to tanks and consumers can serve as energy storage alternatives if properly operated. Nevertheless, optimal WDS scheduling is challenged by the hydraulic law, according to which the pressure along a pipe drops proportionally to its squared water flow (WF). The optimal water flow (OWF) task is formulated here as a mixed-integer nonconvex problem incorporating flow and pressure constraints, critical for the operation of fixed-speed pumps, tanks, reservoirs, and pipes. The hydraulic constraints of the OWF problem are subsequently relaxed to second-order cone constraints. To restore feasibility of the original nonconvex constraints, a penalty term is appended to the objective of the relaxed OWF. The modified problem can be solved as a mixed-integer second-order cone program, which is analytically shown to yield WDS-feasible minimizers under certain sufficient conditions. Under these conditions, by suitably weighting the penalty term, the minimizers of the relaxed problem can attain arbitrarily small optimality gaps, thus providing OWF solutions. Numerical tests using real-world demands and prices on benchmark WDS demonstrate the relaxation to be exact even for setups where the sufficient conditions are not met.

Optimal Scheduling of Water Distribution Systems

A synchronous optimization method for self-pressure drip irrigation pipe network system is proposed. We have generalized the optimization design problem of the system and have established the mathematical models for the simultaneous optimization design of pipeline layout and pipe diameters. A genetic algorithm based on the infeasibility degree of the solution was used to solve the model. A typical example is used to validate the presented method. The method exhibits effective performance in the case studied. Designers can use the results of this study to efficiently design self-pressurized drip irrigation network systems.

https://www.mdpi.com/2073-4441/11/3/489/pdf

Synchronization Optimization of Pipeline Layout and Pipe Diameter Selection in a Self-Pressurized Drip Irrigation Network System Based on the Genetic Algorithm

With dynamic electricity pricing, the operation of water distribution systems (WDS) is expected to become more variable. The pumps moving water from reservoirs to tanks and consumers, can serve as energy storage alternatives if properly operated. Nevertheless, optimal WDS scheduling is challenged by the hydraulic law, according to which the pressure along a pipe drops proportionally to its squared water flow. The optimal water flow (OWF) task is formulated here as a mixed-integer non-convex problem incorporating flow and pressure constraints, critical for the operation of fixed-speed pumps, tanks, reservoirs, and pipes. The hydraulic constraints of the OWF problem are subsequently relaxed to second-order cone constraints. To restore feasibility of the original non-convex constraints, a penalty term is appended to the objective of the relaxed OWF. The modified problem can be solved as a mixed-integer second-order cone program, which is analytically shown to yield WDS-feasible minimizers under certain sufficient conditions. Under these conditions, by suitably weighting the penalty term, the minimizers of the relaxed problem can attain arbitrarily small optimality gaps, thus providing OWF solutions. Numerical tests using real-world demands and prices on benchmark WDS demonstrate the relaxation to be exact even for setups where the sufficient conditions are not met.

This research is aimed at multiple-objective optimization of water operations in a water supply and distribution system. These objectives include reducing energy use while at the same time meeting water quality needs. The first objective is to propose water operations aimed at minimizing energy consumption. The second is to optimize water supply and distribution from the standpoint of water quality based on total organic carbon and the third is to attempt optimization that satisfies the first two objectives through multipurpose fuzzy linear programming (LP). This study mathematically formulates water operation planning issues focusing on reducing energy consumption and improving water quality in a water distribution system. Estimates show that a reduction in energy use of around 10% can be expected. Fuzzy LP is applied to achieve a balance among multiple objectives. The research demonstrates the effectiveness of the proposed multipurpose optimization when applied to trade-offs in water operation.

Optimized operation of water distribution system using multipurpose fuzzy LP model

Minimizing power usage in water distribution system using mixed integer linear programming

The purpose of this study is to propose the optimal water supply control and management plan for minimizing power usage by water distribution pumps. The key topic of this study is to determine from which treatment plants water should be supplied, and through which supply stations it should be distributed. This study devised an optimal model of the ‘route/flow decision problem’ for minimizing power use in the water distribution system while meeting demand in the distributing areas, and formulated the model by means of mixed integer linear programming (MILP). Then to validate the MILP model we attempted a case study in an actual water distribution system. The research demonstrated the effectiveness of the proposed optimization when applied to minimizing power usage in water operation.

Research on minimizing electric power usage in water distribution system

Study on the Reduction of Water Distribution Energy by utilizing the remaining Water Pressure at a Reservoir considering the Water Quality preserving

The vertical profiles of water current and temperature were measured in the Ogouchi Reservoir in order to investigate the mechanism of the water current control by the water preservation facilities.The constant current of 30 mm/s was observed around the vertical fence, it was suggested that these flows were a river inflow.And it was appeared that these flows were directed to the depth of 10 m by the vertical fences, and led to the layer which was the same temperature as the river inflow in center of the reservoir.As results of numerical calculation, the mechanism of the water current control by the vertical fence is reproduced, it was shown that water temperature was decreased in the upstream region of the vertical fence.It was suggested that it is possible to lead efficiently the river inflow by setting the withdrawal gate on the layer of the same temperature as the river inflow.

https://www.jstage.jst.go.jp/article/jscejhe/67/4/67_4_I_1501/_pdf

Atsushi Masuko

Papers

Optimized operation of water distribution system using multipurpose fuzzy LP model

Minimizing power usage in water distribution system using mixed integer linear programming

Research on minimizing electric power usage in water distribution system

Study on the Reduction of Water Distribution Energy by utilizing the remaining Water Pressure at a Reservoir considering the Water Quality preserving

Study on the water current control by the water preservation facilities in ogouchi reservoir