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Balancing and cyclical scheduling of asynchronous mixed-model assembly lines with parallel stations

JOURNAL OF MANUFACTURING SYSTEMS 2019年 50卷 193-200页

作者： Lopes, Thiago Cantos Michels, Adalberto Sato Stall Sikora, Celso Gustavo Magatao, Leandro Fed Univ Technol Parana UTFPR Grad Program Elect & Comp Engn CPGEI Curitiba Parana Brazil Univ Hamburg Hamburg Business Sch Inst Operat Res Hamburg Germany

This paper considers two optimization problems commonly associated to mixed-model assembly lines: balancing task-station assignments and sequencing/scheduling different product models in a cyclical manner. Cyclical scheduling for this particular problem variant is challenging, and multiple approaches have been previously employed by different authors. This paper presents a new mixed-integer linear programming formulation to optimize the steady-state of these lines. Tests on a 36-instance benchmark demonstrated that the proposed model significantly outperformed the previous literature formulation. Furthermore, it is shown that common scheduling rules (often used in simulators) do not necessarily converge to optimal cyclical schedules even when the optimal launch order is used. Tests have also demonstrated that parallelism can allow a marginally increasing value for workstations: doubling (tripling) stations in a line with parallelism can often offer more than double (triple) the optimal throughput of lines without parallelism.

关键词： Assembly line balancing mixed-model sequencing Cyclical scheduling Parallel stations Asynchronous unpaced line mixed-integer linear programming

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Toward a MILP Modeling Framework for Distribution System Restoration

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IEEE TRANSACTIONS ON POWER SYSTEMS 2019年第3期34卷 1749-1760页

作者： Chen, Bo Ye, Zhigang Chen, Chen Wang, Jianhui Argonne Natl Lab Energy Syst Div 9700 S Cass Ave Argonne IL 60439 USA Xi An Jiao Tong Univ State Key Lab Elect Insulat & Power Equipment Xian 710049 Shaanxi Peoples R China Southern Methodist Univ Dept Elect Engn Dallas TX 75205 USA

Large-scale blackouts and extreme weather events in recent decades raise the concern for improving the resilience of electric power infrastructures. Distribution service restoration (DSR), a fundamental application in outage management systems, provides restoration solutions for system operators when power outages happen. As distribution generators (DGs) and remotely controllable devices are increasingly installed in distribution systems, an advanced DSR framework is needed to perform optimally coordinated restoration that can achieve maximal restoration performance. This paper introduces a DSR modeling framework, which can generate optimal switching sequences and estimated time of restoration in the presence of remotely controllable switches, manually operated switches, and dispatchable DGs. Two mathematical models, a variable time step model and a fixed time step model, are presented and compared. The proposed models are formulated as amixed-integer linear programming model, and their effectiveness is evaluated via the IEEE 123 node test feeder.

关键词： Distribution system distributed generation mixed-integer linear programming service restoration switching sequence management

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A matheuristic algorithm for the multi-depot inventory routing problem

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TRANSPORTATION RESEARCH PART E-LOGISTICS AND TRANSPORTATION REVIEW 2019年 122卷 524-544页

作者： Bertazzi, Luca Coelho, Leandro C. De Maio, Annarita Lagana, Demetrio Univ Brescia Dept Econ & Management Brescia Italy Laval Univ CIRRELT Quebec City PQ Canada Laval Univ Canada Res Chair Integrated Logist Quebec City PQ Canada Univ Calabria Dept Mech Energy & Management Engn DIMEG Commenda Di Rende Italy

In this paper we solve a practical Multi-Depot Inventory Routing Problem (MDIRP). One minimizes routing costs by determining how to serve the customers from different depots, managing their inventory levels to avoid stock-outs. The MDIRP optimizes the trade-off between inventory and routing decisions in an integrated way. We formulate this problem as a mixed-integer linear programming model and design a three-phase matheuristic to solve the problem. The solutions of our matheuristic are compared with those from a branch-and-cut algorithm on classical IRP instances, new instances and a real case study, showing to be very effective.

关键词： Multi-depot inventory routing problem mixed-integer linear programming Matheuristic Clustering

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Utilising demand response for distribution service restoration to achieve grid resiliency against natural disasters

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IET GENERATION TRANSMISSION & DISTRIBUTION 2019年第14期13卷 2942-2950页

作者： Hafiz, Faeza Chen, Bo Chen, Chen de Queiroz, Anderson Rodrigo Husain, Iqbal North Carolina State Univ Dept Elect & Comp Engn Raleigh NC 27695 USA Argonne Natl Lab Div Energy Syst 9700 S Cass Ave Argonne IL 60439 USA North Carolina Cent Univ Sch Business Dept Decis Sci Durham NC USA North Carolina State Univ Civil Construct & Environm Engn Dept Raleigh NC USA

The increased frequency of power outages due to natural disasters in recent years has highlighted the urgency of enhancing distribution grid resilience. The effective distribution service restoration (DSR) is an important measure for a resilient distribution grid. In this work, the authors demonstrate that DSR can be significantly improved by leveraging the flexibility provided by the inclusion of demand response (DR). The authors propose a framework for this by considering integrated control of household-level flexible appliances to vary the load demand at the distribution-grid level to improve DSR. The overall framework of the proposed system is modelled as a three-step method considering three optimization problems to (i) calculate feasible controllable aggregated load range for each bus, (ii) determine candidate buses to perform DR and their target load demand, and (iii) maintain the load level in each house through home energy management during the DSR, considering uncertainties in load and solar generation sequentially. The optimization problems are formulated as linear programming, mixed-integer linear programming, and multistage stochastic programming (solved using the stochastic dual dynamic programming) models. Case studies performed in the IEEE 123-node test feeder show improvements in resilience in terms of energy restored compared to the restoration process without DR.

关键词： optimisation power grids energy management systems power distribution control power system restoration demand side management domestic appliances demand response grid resiliency power outages distribution grid resilience resilient distribution grid integrated control household-level flexible appliances distribution-grid level optimisation problems aggregated load target load demand mixed-integer linear programming distribution service restoration IEEE 123-node test feeder system stochastic dual dynamic programming multistage stochastic programming solar generation home energy management

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Robust Control of a Microgrid Energy Storage System Using Various Approaches

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IEEE TRANSACTIONS ON SMART GRID 2019年第3期10卷 2702-2712页

作者： Choi, Jongwoo Shin, Youngmee Choi, Moonok Park, Wan-Ki Lee, Il-Woo Seoul Natl Univ Dept Mech & Aerosp Engn Seoul 08826 South Korea Elect & Telecommun Res Inst IoT Res Div Daejeon 34129 South Korea

This paper presents a robust optimal control strategy for an energy storage system (ESS) of a grid-connected microgrid. The robust optimal control guarantees the highest possible economic benefit of the control schedule even under the worst case net demand prediction error conditions. Several robust optimization approaches are proposed to formulate a fast optimal control problem. The global optimum of a concise control problem can be found within a short computation time using mixed-integer linear programming. The rolling horizon controller of the energy management system periodically updates the control schedule by solving the control problem. The state of charge of an ESS is precisely calculated by the piecewise linearization technique using nonlinear efficiency maps. External working conditions such as peak control and demand response can be dynamically applied during the optimization process. The proposed strategy provides control robustness in terms of cost reduction, precise control, and external effect. Future study will focus on the development of a robust control strategy that considers both the worst and best cases of cost reduction.

关键词： Demand response efficiency map energy management system energy storage system microgrid mixed-integer linear programming peak control robust optimization

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Heuristic solution of a joint electric control reserve and wholesale market model

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International Journal of Modeling, Simulation, and Scientific Computing 2019年第2期10卷 1-20页

作者： Timo Breithaupt Thomas Leveringhaus Lutz Hofmann Institute of Electric Power Systems Leibniz Universit¨at Hannover Welfengarten 1 30167 HanoverGermany

A mixed integer linear programming(MILP)approach for the joint simulation of electric control reserve and electricity wholesale markets is *** generation dispatch model extends an existing integrated grid and electricity market(IGEM)model covering the Continental European electric power *** explicitly incorporating the markets for primary and secondary control reserves(PCR and SCR),the model can reproduce the decisions of generating unit operators on which markets get ***,the introduction of the integrality conditions allows considering start-up costs and the calculus of generating units to pass through the economically unattractive periods with low or even negative prices in order to avoid another *** this model is too large to be solved with common MILP solvers for the intended simulation time of one year,temporal and geographical interdependencies are used to solve it *** heuristic therefore splits the model into various sub-problems so that on the one hand,the number of variables,especially of integer variables,per sub-problem is reduced significantly and on the other hand,the relevant interdependencies remain *** heuristic is evaluated in terms of accuracy and computation time by means of two case *** case studies show satisfactory accuracy and significant advantages in computation time.

关键词： mixed-integer linear programming unit commitment rolling horizon heuristic

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A decomposition-based heuristic for large employee scheduling problems with inter-department transfers

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EURO JOURNAL ON COMPUTATIONAL OPTIMIZATION 2019年第4期7卷 325-357页

作者： Attia, Dalia Burgy, Reinhard Desaulniers, Guy Soumis, Francois Polytech Montreal Dept Math & Genie Ind Montreal PQ Canada Gerad Montreal PQ Canada Univ Fribourg Dept Informat Fribourg Switzerland

We consider a personalized employee scheduling problem with characteristics present in retail stores consisting of multiple departments. In the setting under study, each department generally covers its demand in employees over the planning horizon of a week by assigning shifts to its own staff. However, the employees can also be transferred to other departments under certain conditions for executing entire shifts or parts of shifts there. The transfer feature enables to improve the overall schedule quality considerably when compared to the nontransfer case. Given the complexity of the problem, we propose a three-phase decomposition-based heuristic. In the first phase, we consider each department separately and solve a simplified version of the mono-department scheduling problems. From the obtained solutions, we deduce inter-department shifts that could potentially reduce the overall cost. This is examined in the second phase by resolving the scheduling problem of the first phase where the deduced inter-department shifts are included. In this phase, however, we decompose the scheduling problem by time, looking at each day separately. From the obtained schedules, we then devise inter-department demand curves, which specify the number of transfers between departments over time. In the third phase, we decompose the initial scheduling problem into mono-department problems using these inter-department demand curves. Consequently, our approach makes it possible to solve mono-department optimization problems to get an overall schedule while still benefiting from the employee transfer feature. In all three phases, the scheduling problems are formulated as mixed-integer linear programs. We show through extensive computational experiments on instances with up to 25 departments and 1000 employees that the method provides high-quality solutions within reasonable computation times.

关键词： Employees scheduling Shift scheduling Multi-department Retail industry Heterogeneous workforce mixed-integer linear programming Decomposition

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FORM FOLLOWS AVAILABILITY - DESIGNING STRUCTURES THROUGH REUSE

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JOURNAL OF THE INTERNATIONAL ASSOCIATION FOR SHELL AND SPATIAL STRUCTURES 2019年第4期60卷 257-265页

作者： Bruetting, Jan Senatore, Gennaro Fivet, Corentin Swiss Fed Inst Technol Lausanne EPFL Struct Xplorat Lab Lausanne Switzerland Swiss Fed Inst Technol Lausanne EPFL Appl Comp & Mech Lab Lausanne Switzerland

This work proposes a new direction in structural design: the synthesis of structures through the reuse of elements. Reusing structural elements reduces the environmental impacts of building structures because it avoids sourcing new material, it reduces waste and it requires little energy. Designing structures from reused elements is unlike conventional structural design because stock element availability is a design input. In other words, structures must be designed subject to availability of given element characteristics such as length and cross-section type, which have a major influence on the optimal structure layout and form. In this new paradigm structural form follows availability. In this work new computational methods for the synthesis of reticular structures through reuse are formulated to address two scenarios: a) reuse of reclaimed elements from a given stock, and b) design of an element stock which is used as a kit of parts to build diverse structures. Case studies are presented to demonstrate the potential of the proposed methods. It is shown that structures produced by these methods have a significantly lower environmental impact than minimum weight structures made of new elements.

关键词： Structural design discrete optimization geometry optimization mixed-integer linear programming reuse Life Cycle Assessment environmental impact

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Optimal urban sewer layout design using Steiner tree problems

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ENGINEERING OPTIMIZATION 2019年第11期51卷 1980-1996页

作者： Hsie, Machine Wu, Ming-Yen Huang, Chun Yen Natl Chung Hsing Univ Dept Civil Engn Taichung Taiwan

This article introduces a novel method using mixed-integer linear programming for optimizing sewer layouts. The research concept was obtained from the obstacle-avoiding rectilinear Steiner minimal tree technique in integrated circuit routing design. The Steiner nodes serve as optional nodes to link each sewer discharge node and flow to sinks on an optimal sewer layout. Those nodes are utilized for minimizing the total cost required for constructing pipes. All the nonlinear constraints and the objective function are transformed into a simple linear format. The optimization model analysed three types of objective function conditions-solely considering the pipe cost, solely considering the ground-cutting cost, and combining both considerations-to illustrate the importance of considering all conditions to obtain an optimal sewer layout design. The proposed optimization model can save more than 38.83% of the cost required to realize the expert's manual sewer layout design.

关键词： Optimization sewer layout Steiner minimal tree mixed-integer linear programming

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Modelo linearizado para problemas de planejamento da operação de sistemas de distribuição considerando incertezas

Modelo linearizado para problemas de planejamento da operaç...

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作者： Ferraz, Bibiana Maitê Petry

This work presents a linearized model that can be applied to the planning of the operation of power distribution systems (PDS) considering uncertainties. To minimize the operation costs of distribution systems containing distributed energy resources (DERs), the model includes decentralized strategies for volt-var control which include capacitor banks (CBs) and voltage regulators (VRs). These strategies aim to reduce the power losses and also increase the power factor, thus improving the voltage levels and the PDS load factor. According to the proposed formulation, regulation devices become sensitive to downstream load variations, since inside each control strategy of VRs, the model uses explicit current variables to handle the operation of automatic CBs, and since it includes means to compensate voltage drops along distribution lines. Further, the inherent uncertainties of DERs and load demand are represented through typical operational scenarios, selected using the K-means clustering algorithm. In this way, the simultaneity and chronological combination of different loads and DERs are preserved through a set of K scenarios, which simplifies the PDS operation analysis, given that a reduced number of possible states are required. Besides, the proposed approach considers the effect of the propagation of uncertainties on the operating costs, energy losses, and violation of voltage limits. Further, the steady-state operation point is calculated through a linearized model of the network. Thus, the optimization model proposed to solve these problems uses a linear objective function, along with linear constraints, binary and continuous variables. Therefore, the optimization model can be represented as a mixed-integer linear programming problem (MILP), which in addition to guaranteed optimality of a given feasible solution allows the use of classical optimization methods to find the solution. The model is validated by comparing the results obtained during several tests of t

关键词： Distribution system operation planning Energia elétrica : Distribuição mixed-integer linear programming Uncertainties Volt-var control K-means clustering Tese

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