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An advanced model for the efficient and reliable short-term operation of insular electricity networks with high renewable energy sources penetration

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RENEWABLE & SUSTAINABLE ENERGY REVIEWS 2014年 38卷 415-427页

作者： Simoglou, Christos K. Kardakos, Evaggelos G. Bakirtzis, Emmanouil A. Chatzigiannis, Dimitris I. Vagropoulos, Stylianos I. Ntomaris, Andreas V. Biskas, Pandelis N. Gigantidou, Antiopi Thalassinakis, Emmanouil J. Bakirtzis, Anastasios G. Catalao, Joao P. S. Aristotle Univ Thessaloniki Dept Elect & Comp Engn Power Syst Lab GR-54124 Thessaloniki Greece Hellen Elect Distribut Network Operator SA HEDNO Iraklion 71307 Greece Univ Beira Interior Dept Electromech Engn P-6201001 Covilha Portugal

This paper presents an overview of the different methodologies and mathematical optimization models developed in the framework of the EU-funded project SiNGULAR towards the optimal exploitation and efficient short-term operation of RES production in insular electricity networks. Specifically, the algorithms employed for the creation of system load and RES production scenarios that capture the spatial and temporal correlations of the corresponding variables as well as the procedure followed for the creation of units' availability scenarios using Monte Carlo simulation are discussed. In addition, the advanced unit commitment and economic dispatch models, that have been developed for the short-term scheduling of the conventional and RES generating units in different short-term time-scales (day-ahead, intra-day, and real-time) are presented. Indicative test results from the implementation of all models in the pilot system of the island of Crete, Greece, are illustrated and valuable conclusions are drawn. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： Day-ahead market Insular power systems Mathematical modeling mixed-integer linear programming RES integration Scenario generation

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Biologically guided intensity modulated radiation therapy planning optimization with fraction-size dose constraints

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JOURNAL OF THE OPERATIONAL RESEARCH SOCIETY 2014年第4期65卷 557-571页

作者： Saka, Behlul Rardin, Ronald L. Langer, Mark P. Elekta Software Treatment Planning Syst Maryland Hts MO 63043 USA Univ Arkansas Fayetteville AR 72701 USA Indiana Univ Indianapolis IN 46204 USA

Although intensity modulated radiation therapy plans are optimized as a single overall treatment plan, they are delivered over 30-50 treatment sessions (fractions) and both cumulative and per-fraction dose constraints apply. Recent advances in imaging technology provide more insight on tumour biology that has been traditionally disregarded in planning. The current practice of delivering physical dose distributions across the tumour may potentially be improved by dose distributions guided by the biological responses of the tumour points. The biological optimization models developed and tested in this paper generate treatment plans reacting to the tumour biology prior to the treatment as well as the changing tumour biology throughout the treatment while satisfying both cumulative and fraction-size dose limits. Complete computational testing of the proposed methods would require an array of clinical data sets with tumour biology information. Finding no open source ones in the literature, the authors sought proof of concept by testing on a simulated head-and-neck case adapted from a more standard one in the CERR library by blending it with available tumour biology data from a published study. The results show computed biologically optimized plans improve on tumour control obtained by traditional plans ignoring biology, and that such improvements persist under likely uncertainty in sensitivity values. Furthermore, adaptive plans using biological information improve on non-adaptive methods.

关键词： radiation therapy planning tumour biology and hypoxia fractionation biological optimization mixed-integer linear programming modelling

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

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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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Taxing Strategies for Carbon Emissions: A Bilevel Optimization Approach

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ENERGIES 2014年第4期7卷 2228-2245页

作者： Wei, Wei Liang, Yile Liu, Feng Mei, Shengwei Tian, Fang Tsinghua Univ Dept Elect Engn State Key Lab Control & Simulat Power Syst & Gene Beijing 100084 Peoples R China Elect Power Res Inst China Beijing 100192 Peoples R China

This paper presents a quantitative and computational method to determine the optimal tax rate among generating units. To strike a balance between the reduction of carbon emission and the profit of energy sectors, the proposed bilevel optimization model can be regarded as a Stackelberg game between the government agency and the generation companies. The upper-level, which represents the government agency, aims to limit total carbon emissions within a certain level by setting optimal tax rates among generators according to their emission performances. The lower-level, which represents decision behaviors of the grid operator, tries to minimize the total production cost under the tax rates set by the government. The bilevel optimization model is finally reformulated into a mixed integer linear program (MILP) which can be solved by off-the-shelf MILP solvers. Case studies on a 10-unit system as well as a provincial power grid in China demonstrate the validity of the proposed method and its capability in practical applications.

关键词： bilevel optimization carbon emission tax mixed-integer linear programming

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Lagrangian relaxation based decomposition for well scheduling in shale-gas systems

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COMPUTERS & CHEMICAL ENGINEERING 2014年 63卷 234-249页

作者： Knudsen, Brage Rugstad Grossmann, Ignacio E. Foss, Bjarne Conn, Andrew R. Norwegian Univ Sci & Technol Dept Engn Cybernet N-7034 Trondheim Norway Carnegie Mellon Univ Dept Chem Engn Pittsburgh PA 15213 USA IBM Corp TJ Watson Res Ctr Yorktown Hts NY 10598 USA

Suppressing the effects of liquid loading is a key issue for efficient utilization of mid and late-life wells in shale-gas systems. This state of the wells can be prevented by performing short shut-ins when the gas rate falls below the minimum rate needed to avoid liquid loading. In this paper, we present a Lagrangian relaxation scheme for shut-in scheduling of distributed shale multi-well systems. The scheme optimizes shut-in times and a reference rate for each multi-well pad, such that the total produced rate tracks a given short-term gas demand for the field. By using simple, frequency-tuned well proxy models, we obtain a compact mixed-integer formulation which by Lagrangian relaxation renders a decomposable structure. A set of computational tests demonstrates the merits of the proposed scheme. This study indicates that the method is capable of solving large field-wide scheduling problems by producing good solutions in reasonable computation times. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： Lagrangian relaxation mixed-integer linear programming Shale-gas production Parameter estimation

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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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Scheduling dynamically positioned tankers for offshore oil offloading

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INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH 2014年第24期52卷 7251-7261页

作者： Camponogara, Eduardo Plucenio, Agustinho Univ Fed Santa Catarina Dept Automat & Syst Engn Florianopolis SC Brazil

The operation of offshore oil fields entails transferring oil that accumulates in Floating Production Storage and Offloading Units to onshore terminals. To this end, a fleet of dynamically positioned tankers is deployed for transferring oil from large oil fields, which should be scheduled to meet operational constraints while minimising costs and economic losses. This work presents a mixed-integer linear programming (MILP) formulation for the problem of scheduling shuttle tankers that accounts for the essential constraints. Combined with an MILP solver, the model serves as a decision support tool to guide engineers in daily operations. A family of valid inequalities is proposed to strengthen the MILP formulation and reduce solving time with state-of-the-art solvers. Computational results are also reported on the application of the proposed model in tandem with a rolling horizon strategy.

关键词： shuttle tankers mixed-integer linear programming offshore oil operations rolling horizon strategy valid inequalities

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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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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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New formulations of the 'energy hub' model to address operational constraints

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ENERGY 2014年 73卷 387-398页

作者： Evins, Ralph Orehounig, Kristina Dorer, Viktor Carmeliet, Jan Swiss Fed Inst Technol Chair Bldg Phys ETH Honggerberg CH-8093 Zurich Switzerland Swiss Fed Labs Mat Sci & Technol EMPA CH-8600 Dubendorf Switzerland

We present new formulations of the 'energy hub' model and evaluate their performance. The energy hub model consists of a mixed-integer linear programming problem that balances energy demand and supply between multiple energy carriers by determining the optimal conversion and storage schedule within certain constraints. The new formulations extend the model to account for performance constraints concerning system efficiencies, storage losses and operating limits. Each formulation allows a more accurate representation of real plant performance to be included in the optimisation, giving more accurate optimised schedules and carbon emissions totals. The first major innovation is a means of limiting the number of state changes (startups or shutdowns). This is achieved by specifying a minimum time for which the plant must operate once it is running. The second innovation is the use of stepwise approximations of efficiency curves, thus allowing part-load behaviour to be accurately simulated using a linear model. The third innovation adds a storage loss term that is a percentage of the current amount stored, rather than a fixed value. The new formulations are demonstrated in an example case, where the impact on the optimal schedule is observed. They are also analysed for each week of the heating season, and their impact on the time taken to find the optimal solution is also discussed. Overall changes in the predicted carbon emissions of up to 22% were found, highlighting the importance of accurate plant representation in energy hub models. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： Energy hub mixed-integer linear programming Constraints Optimisation

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