Convergence of a Hydraulic Solver with Pressure-Dependent Demands

2016

This paper describes the development and application of a new multiobjective evolutionary optimization approach for the design and upgrading of water distribution systems with multiple pumps and service reservoirs. The optimization model employs a pressure-driven analysis simulator that accounts for the minimum node pressure constraints and conservation of mass and energy. Pump scheduling, tank siting and tank design are integrated seamlessly in the optimization without introducing additional heuristic procedures. The computational solution of the optimization problem is entirely penalty-free, thanks to pressure-driven analysis and the inclusion of explicit criteria for tank depletion and replenishment. The model was applied to the Anytown network that is a benchmark optimization problem. Many new solutions were achieved that are cheaper and offer superior performance compared to previous solutions in the literature. Detailed and extensive simulations of the solutions achieved were carried out. Spatial and temporal variations in water quality were investigated by simulating the chlorine residual and disinfection by-products in addition to water age. The hydraulic requirements were satisfied; efficiency of pumps was consistently high; effective operation of the new and existing tanks was achieved; water quality was improved; and overall computational efficiency was high. The formulation is entirely generic.Keywords Demand-driven analysis . Pressure-driven analysis . Penalty-free constrained multiobjective evolutionary optimization . Water distribution system . Optimal pump scheduling . Service reservoir design and operation Water Resour Manage (2016) 30:3671-3688

Section: Formulation Of the Optimization Modelmentioning

confidence: 99%

Penalty-Free Multi-Objective Evolutionary Approach to Optimization of Anytown Water Distribution Network

Siew

2016

“…tanks, pumps and control devices. Control devices such as pressure regulating valves make the equations for water distribution systems more difficult to solve (Kovalenko et al 2014;Elhay et al 2015). The accuracy and reliability of the EPANET-PDX results were verified previously .…”

Section: Reliability and Quality Of The Network Modelling Resultsmentioning

confidence: 56%

“…Kovalenko et al (2014) and Elhay et al (2015), for example, excluded key elements e.g. tanks, pumps and control devices.…”

Section: Reliability and Quality Of The Network Modelling Resultsmentioning

confidence: 99%

“…The most efficient approach for pressure-driven analysis involves embedding the relationship between the flow and pressure at a demand node in the system of hydraulic equations (Ciaponi et al 2015;Elhay et al 2015;Kovalenko et al 2014). The source code of EPANET 2 was modified recently to provide a pressure-driven model called EPANET-PDX (pressuredependent extension) by incorporating a logistic pressuredriven demand function (Tanyimboh and Templeman 2010) in the global gradient algorithm (Todini and Pilati 1988).…”

Section: Introductionmentioning

confidence: 99%

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Integration of Hydraulic and Water Quality Modelling in Distribution Networks: EPANET-PMX

2017

Simulation models for water distribution networks are used routinely for many purposes. Some examples are planning, design, monitoring and control. However, under conditions of low pressure, the conventional models that employ demand-driven analysis often provide misleading results. On the other hand, almost all the models that employ pressure-driven analysis do not perform dynamic and/or water quality simulations seamlessly. Typically, they exclude key elements such as pumps, control devices and tanks. EPANET-PDX is a pressure-driven extension of the EPANET 2 simulation model that preserved the capabilities of EPANET 2 including water quality modelling. However, it cannot simulate multiple chemical substances at once. The single-species approach to water quality modelling is inefficient and somewhat unrealistic. The reason is that different chemical substances may co-exist in water distribution networks. This article proposes a fully integrated network analysis model (EPANET-PMX) (pressure-dependent multi-species extension) that addresses these weaknesses. The model performs both steady state and dynamic simulations. It is applicable to any network with various combinations of chemical reactions and reaction kinetics. Examples that demonstrate its effectiveness are included.

“…By contrast, some investigations into pressure-driven analysis (e.g. Kovalenko et al 2014;Elhay et al 2015) did not consider extended period simulation. Furthermore, they excluded key elements e.g.…”

Section: Introductionmentioning

confidence: 99%

Investigation into the Pressure-Driven Extension of the EPANET Hydraulic Simulation Model for Water Distribution Systems

2016

Several hydraulic modelling approaches have been proposed previously to simulate pressure -deficient operating conditions in water distribution networks more realistically. EPANET-PDX is a pressure-driven extension of the EPANET 2 hydraulic simulation model that has an embedded logistic nodal head-flow function. The pressure-driven analysis algorithm in EPANET-PDX was investigated, to improve its performance under conditions of extremely low pressure. By integrating a line minimization procedure fully in the computational solution of the system of equations, the algorithm's consistency was improved by increasing its computational efficiency under conditions of extremely low pressure. The examples considered demonstrated that the pressure-driven analysis algorithm proposed is robust, computationally efficient, and the line minimization procedure is applied frequently. Overall, the results suggest that the algorithm is reliable. The formulation proposed is significantly faster than the previous model under conditions of extremely low pressure. The hydraulic and water quality modelling functionality of EPANET 2 was preserved. For the operating conditions with satisfactory pressure, where direct comparisons with EPANET 2 were possible, EPANET 2 was consistently faster.