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An efficient optimization procedure for designing a capacitated distribution network with price-sensitive demand

OPTIMIZATION AND ENGINEERING 2014年第3期15卷 801-817页

作者： Ahmadi-Javid, Amir Ghandali, Razieh Amirkabir Univ Technol Dept Ind Engn Tehran Iran

This paper considers a location-allocation problem in a supply-chain distribution network with capacitated distribution centers and customers with price-sensitive demands. The problem determines location, allocation and price decisions in order to maximize the total profit under two supply policies. Serving all of the customers is compulsory under the first policy, but is optional under the second. The problem is formulated as a mixed-integer linear program and solved by a Lagrangian relaxation algorithm under each policy. The numerical study indicates that the proposed algorithms are highly efficient and effective for solving large-sized instances of the problem.

关键词： Capacitated location-allocation problem Distribution network Integration Price-sensitive demands Pricing Lagrangian relaxation method mixed-integer linear programming Supply chain management

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Optimal train routing and scheduling for managing traffic perturbations in complex junctions

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TRANSPORTATION RESEARCH PART B-METHODOLOGICAL 2014年 59卷 58-80页

作者： Pellegrini, Paola Marliere, Gregory Rodriguez, Joaquin Univ Lille Nord France Ifsttar ESTAS F-59666 Villeneuve Dascq France

Real-time traffic management in railway aims to minimize delays after an unexpected event perturbs the operations. It can be formalized as the real-time railway traffic management problem, which seeks for the best train routing and scheduling in case of perturbation, in a given time horizon. We propose a mixed-integer linear programming formulation for tackling this problem, representing the infrastructure with fine granularity. This is seldom done in the literature, unless stringent artificial constraints are imposed for reducing the size of the search space. In a thorough experimental analysis, we assess the impact of the granularity of the representation of the infrastructure on the optimal solution. We tackle randomly generated instances representing traffic in the control area named triangle of Gagny, and instances obtained from the real timetable of the control area including the Lille-Flandres station (both in France) and we consider multiple perturbation scenarios. In these experiments, the negative impact of a rough granularity on the delay suffered by trains is remarkable and statistically significant. (C) 2013 Elsevier Ltd. All rights reserved.

关键词： Real-time railway traffic management problem mixed-integer linear programming Track-circuit Complex junction Routing Scheduling

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Integrating electric vehicles as flexible load in unit commitment modeling

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ENERGY 2014年 65卷 285-294页

作者： Madzharov, D. Delarue, E. D'haeseleer, W. Univ Leuven KU Leuven Energy Inst TME Branch Appl Mech & Energy Convers B-3001 Louvain Belgium

Fully EVs (electric vehicles) and PHEVs (plug-in hybrid electric vehicles) have attracted much attention in recent years. Towards an increasing share of EVs, their economic feasibility and impact on the electricity distribution have been studied in detail. However, little has been achieved in investigating the impact on the electricity generation systems. This paper presents a MILP (mixed-integer linear programming) unit commitment model with focus on the effect of EVs on the generation side. The most important advantage of the proposed method is the ability to solve systems with a very large number of EVs. The algorithm is demonstrated on a benchmark system, which has been widely used in the literature and has been used here for all scenarios. It is demonstrated that optimized charging (centrally controlled) is cheaper and allows for higher EV penetration, compared to random charging. Simulations were also run for two scenarios based on the advancement in the charging infrastructure: (1) perfect infrastructure, with opportunity for charging everywhere and (2) moderate infrastructure, where charging is possible only at the owners' homes. In both cases the generation cost increases by 1% for every 10% of additional EV penetration, the modest infrastructure case being slightly more expensive. (C) 2013 Elsevier Ltd. All rights reserved.

关键词： Electric vehicles Electricity generation systems Unit commitment Flexible load mixed-integer linear programming

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A DEA based procedure for the selection of subgroups

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APPLIED MATHEMATICAL MODELLING 2014年第17-18期38卷 4538-4547页

作者： Contreras, I. Brey, R. Carazo, A. F. Brey, J. J. Pablo De Olavide Univ Dept Econ Seville 41013 Spain Hynergreen Technol SA Seville 41014 Spain

Data Envelopment Analysis (DEA) is a nonparametric technique originally conceived for efficiency analysis of a set of units. The main characteristic of DEA based procedures is endogenous determination of weighting vectors, i.e., the weighting vectors are determined as variables of the model. Nevertheless, DEA's applications have vastly exceeded its original target. In this paper, a DEA based model for the selection of a subgroup of alternatives or units is proposed. Considering a set of alternatives, the procedure seeks to determine the group that maximizes overall efficiency. The proposed model is characterized by free selection of weights and allows the inclusion of additional information, such as agent's preferences in terms of relative importance of the variables under consideration or interactions between alternatives. The solution is achieved by computing a mixed-integer linear programming model. Finally, the proposed model is applied to plan the deployment of filling stations in the province of Seville (Spain). (C) 2014 Elsevier Inc. All rights reserved.

关键词： DEA Group selection mixed-integer linear programming

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Evaluation of the electric vehicle impact in the power demand curve in a smart grid environment

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ENERGY CONVERSION AND MANAGEMENT 2014年 82卷 268-282页

作者： Morais, Hugo Sousa, Tiago Vale, Zita Faria, Pedro Tech Univ Denmark DTU Dept Elect Engn Automat & Control Grp DK-2800 Lyngby Denmark Polytech Porto IPP GECAD Knowledge Engn & Decis Support Res Ctr P-4200072 Oporto Portugal

Smart grids with an intensive penetration of distributed energy resources will play an important role in future power system scenarios. The intermittent nature of renewable energy sources brings new challenges, requiring an efficient management of those sources. Additional storage resources can be beneficially used to address this problem;the massive use of electric vehicles, particularly of vehicle-to-grid (usually referred as gridable vehicles or V2G), becomes a very relevant issue. This paper addresses the impact of Electric Vehicles (EVs) in system operation costs and in power demand curve for a distribution network with large penetration of Distributed Generation (DG) units. An efficient management methodology for EVs charging and discharging is proposed, considering a multi-objective optimization problem. The main goals of the proposed methodology are: to minimize the system operation costs and to minimize the difference between the minimum and maximum system demand (leveling the power demand curve). The proposed methodology perform the day-ahead scheduling of distributed energy resources in a distribution network with high penetration of DG and a large number of electric vehicles. It is used a 32-bus distribution network in the case study section considering different scenarios of EVs penetration to analyze their impact in the network and in the other energy resources management. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： Distributed generation Power demand curve mixed-integer linear programming Smart grid Vehicle-to-grid

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Wireless sensor network lifetime maximization by optimal sensor deployment, activity scheduling, data routing and sink mobility

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AD HOC NETWORKS 2014年 17卷 18-36页

作者： Keskin, M. Emre Altinel, I. Kuban Aras, Necati Ersoy, Cem Bogazici Univ Dept Ind Engn TR-34342 Istanbul Turkey Bogazici Univ Dept Comp Engn TR-34342 Istanbul Turkey

The longevity of Wireless Sensor Networks (WSNs) is a crucial concern that significantly influences their applicability in a specific context. Most of the related literature focuses on communication protocols aiming to reduce the energy consumption which would eventually lead to longer network lifetimes. On the other hand, a limited number of studies concentrate on providing a unifying frame to investigate the integrated effect of the important WSN design decisions such as sensor places, activity schedules, data routes, trajectory of the mobile sink(s), along with the tactical level decisions including the data propagation protocols. However, a monolithic mathematical optimization model with a practically applicable, efficient, and accurate solution method is still missing. In this study, we first provide a mathematical model which integrates WSN design decisions on sensor places, activity schedules, data routes, trajectory of the mobile sink(s) and then present two heuristic methods for the solution of the model. We demonstrate the efficiency and accuracy of the heuristics on several randomly generated problem instances on the basis of extensive numerical experiments. (C) 2014 Elsevier B.V. All rights reserved.

关键词： Sensor deployment Activity scheduling Controlled sink mobility Lifetime maximization mixed-integer linear programming

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Optimizing biogas plants with excess power unit and storage capacity in electricity and control reserve markets

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BIOMASS & BIOENERGY 2014年 65卷 125-135页

作者： Hochloff, Patrick Braun, Martin Fraunhofer Inst Wind Energy & Energy Syst Technol D-34119 Kassel Germany Univ Kassel Kassel Germany

Increasing shares of intermittent power sources such as solar and wind will require biomass fueled generation more variable to respond to the increasing volatility of supply and demand. Furthermore, renewable energy sources will need to provide ancillary services. Biogas plants with excess generator capacity and gas storages can adapt the unit commitment to the demand and the market prices, respectively. This work presents a method of day-ahead unit commitment of biogas plants with excess generator capacity and gas storage participating in short-term electricity and control reserve markets. A biogas plant with 0.6 MW annual average electric output is examined in a case study under German market conditions. For this biogas plant different sizes of the power units and the gas storage are compared in consideration of costs and benefits of installing excess capacity. For optimal decisions depending on prices, a mixed-integer linear programming (MILP) approach is presented. The results show that earnings of biogas plants in electricity markets are increased by additional supplying control reserve. Furthermore, increasing the installed capacity from 0.6 MW to 1 MW (factor 1.7) leads to the best cost benefit-ratio in consideration of additional costs of excess capacity and additional market revenues. However, the result of the cost benefit-analysis of installing excess capacity is still negative. Considering the EEG flexibility premium, introduced in 2012 in the German renewable energy sources act, the result of the cost benefit-analysis is positive. The highest profit is achieved with an increase of the installed capacity from 0.6 MW to 2 MW (factor 3.3). (c) 2013 Elsevier Ltd. All rights reserved.

关键词： Biogas plants Gas storage Unit commitment mixed-integer linear programming Electricity market Ancillary services

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mixed-integer linear methods for layout-optimization of screening systems in recovered paper production

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OPTIMIZATION AND ENGINEERING 2014年第2期15卷 533-573页

作者： Fuegenschuh, Armin Hayn, Christine Michaels, Dennis Univ Bundeswehr Hamburg Helmut Schmidt Univ D-22043 Hamburg Germany Univ Erlangen Nurnberg D-91058 Erlangen Germany Tech Univ Dortmund D-44227 Dortmund Germany

The industrial treatment of waste paper in order to regain valuable fibers from which recovered paper can be produced, involves several steps of preparation. One important step is the separation of stickies that are normally attached to the paper. If not properly separated, remaining stickies reduce the quality of the recovered paper or even disrupt the production process. For the mechanical separation process of fibers from stickies a separator screen is used. This machine has one input feed and two output streams, called the accept and the reject. In the accept the fibers are concentrated, whereas the reject has a higher concentration of stickies. The machine can be controlled by setting its reject rate. But even when the reject rate is set properly, after just a single screening step, the accept still has too many stickies, or the reject too many fibers. To get a better separation, several separators have to be assembled into a network. From a mathematical point of view this problem can be seen as a multi-commodity network flow design problem with a nonlinear, controllable distribution function at each node. We present a nonlinear mixed-integer programming model for the simultaneous selection of the network's topology and the optimal setting of each separator. Numerical results are obtained via different types of linearization of the nonlinearities and the use of mixed-integer linear solvers, and compared with state-of-the-art global optimization software.

关键词： mixed-integer linear programming Nonlinear programming Piecewise linear approximation Global optimization linear relaxation Topology optimization Network design

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ISO's Optimal Strategies for Scheduling the Hourly Demand Response in Day-Ahead Markets

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IEEE TRANSACTIONS ON POWER SYSTEMS 2014年第6期29卷 2636-2645页

作者： Parvania, Masood Fotuhi-Firuzabad, Mahmud Shahidehpour, Mohammad Univ Calif Davis Dept Elect & Comp Engn Davis CA 95616 USA Sharif Univ Technol Dept Elect Engn Ctr Excellence Power Syst Control & Management Tehran 113659363 Iran IIT Galvin Ctr Elect Innovat Chicago IL 60616 USA

This paper presents a hierarchical demand response (DR) bidding framework in the day-ahead energy markets which integrates customer DR preferences and characteristics in the ISO's market clearing process. In the proposed framework, load aggregators submit aggregated DR offers to the ISO which would centrally optimize final decisions on aggregators' DR contributions in wholesale markets. The hourly load reduction strategies include load shifting and curtailment and the use of onsite generation and energy storage systems. The ISO applies mixed-integer linear programming (MILP) to the solution of the proposed DR model in the day-ahead market clearing problem. The proposed model is implemented using a 6-bus system and the IEEE-RTS, and several studies are conducted to demonstrate the merits of the proposed DR model.

关键词： Day-ahead scheduling equivalent load aggregation hourly demand response mixed-integer linear programming

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A facility-location model for biofuel plants: Applications in the Colombian context

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ENERGY 2014年 72卷 476-483页

作者： Duarte, Alexandra E. Sarache, William A. Costa, Yasel J. Univ Nacl Colombia Sede Manizales Colombia Univ Manizales Manizales Colombia

To reduce the logistical and operating costs for biofuel plants, it is important to make a strategic decision to select the proper site for a new facility. Due to the facility's complexity, the facility-location problem must consider the supply-chain structure, involving the material flow from suppliers to customers. This paper proposes an optimisation framework that combines the process design and configuration of the supply chain using an MILP (mixed-integer linear programming) formulation. The model was applied to locate a second-generation bioethanol plant in Colombia that uses an agricultural residue known as Coffee-CSs (coffee cut stems). The experimental results indicate that placing a processing plant at Ibague city results in the best profitability. A post-optimisation analysis indicated that even for a long period, the location decision did not change. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： Facility location Bioethanol mixed-integer linear programming Optimisation Coffee cut stem

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