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A new mixed-integer linear formulation for optimal placement of fault indicators in distribution systems

INTERNATIONAL TRANSACTIONS ON ELECTRICAL ENERGY SYSTEMS 2018年第12期28卷

作者： Derakhshandeh, Sayed Yaser Nikbakht, Mojtaba Shahrekord Univ Dept Engn Shahrekord Iran

In distribution systems, fault indicators (FIs) are used for fast faulted line-section location. Locations and the numbers of FIs affect the reliability indices of distribution companies and customers. This study presents a new linear method to find the optimum numbers and locations of FIs in distribution systems. Fault indicator placement of FIs is defined as an optimization problem whose aim is to improve the reliability indices with regard to the costs imposed on the system. The structure of the proposed formulation is mixed-integer linear programming. The proposed approach finds the optimal locations for FIs in such a way that customers' interruption cost and investment costs for the installation of FIs are minimized. The proposed formulation can be solved by using commercial solvers in a computational effective manner and rapidly converges to the global optimum. To evaluate the effectiveness of the proposed mixed-integer linear programming optimization formulation, several studies are presented and tested on bus number 4 of the reliability test system.

关键词： distribution system fault indicator mixed-integer linear programming optimal placement reliability

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Preventing ergonomic risks with integrated planning on assembly line balancing and parts feeding

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INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH 2017年第24期55卷 7452-7472页

作者： Battini, Daria Calzavara, Martina Otto, Alena Sgarbossa, Fabio Univ Padua Dept Management & Engn Vicenza Italy Univ Siegen Chair Management Informat Sci Siegen Germany

In this paper, we advise to perform assembly line balancing simultaneously with decision-making on parts feeding. Such integrated planning may open additional potential to reduce labour costs. Additional planning flexibility gained with the integrated planning may be used to mitigate ergonomic risks at workplaces. We formulate the integrated assembly line balancing and parts feeding planning problem, propose a mixed-integer model and compare integrated planning to a common hierarchical planning approach in a detailed case study on the assembly of a self-priming pump. Our case study illustrates that workplaces with high ergonomic risks may emerge even in productions that involve handling parts and workpieces of low weights and avoid static and awkward postures. We also show that the proposed integrated planning approach may eliminate excessive ergonomic risks and improve productivity indicators simultaneously.

关键词： assembly line balancing part feeding mixed-integer linear programming ergonomic risks case study

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Chance-constrained Scheduling of Variable Generation and Energy Storage in a Multi-Timescale Framework

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JOURNAL OF ELECTRICAL ENGINEERING & TECHNOLOGY 2017年第5期12卷 1709-1718页

作者： Tan, Wen-Shan Abdullah, Md Pauzi Shaaban, Mohamed Univ Teknol Malaysia Inst Future Energy Ctr Elect Energy Syst Johor Baharu 81310 Malaysia Univ Malaysia Sarawak Fac Engn Dept Elect & Elect Engn Kota Samarahan 94300 Sarawak Malaysia

This paper presents a hybrid stochastic deterministic multi-timescale scheduling (SDMS) approach for generation scheduling of a power grid. SDMS considers flexible resource options including conventional generation flexibility in a chance-constrained day-ahead scheduling optimization (DASO). The prime objective of the DASO is the minimization of the daily production cost in power systems with high penetration scenarios of variable generation. Furthermore, energy storage is scheduled in an hourly-ahead deterministic real-time scheduling optimization (RTSO). DASO simulation results are used as the base starting-point values in the hour-ahead online rolling RTSO with a 15-minute time interval. RTSO considers energy storage as another source of grid flexibility, to balance out the deviation between predicted and actual net load demand values. Numerical simulations, on the IEEE RTS test system with high wind penetration levels, indicate the effectiveness of the proposed SDMS framework for managing the grid flexibility to meet the net load demand, in both day-ahead and real-time timescales. Results also highlight the adequacy of the framework to adjust the scheduling, in real-time, to cope with large prediction errors of wind forecasting.

关键词： Multi-timescale scheduling Energy storage mixed-integer linear programming Unit commitment Wind generation

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Two-machine flow shop problem with unit-time operations and conflict graph

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INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH 2017年第6期55卷 1664-1679页

作者： Tellache, Nour El Houda Boudhar, Mourad USTHB Univ Fac Math RECITS Lab Bab Ezzouar Algeria

This paper addresses the problem of scheduling, on a two-machine flow shop, a set of unit-time operations subject to the constraints that some conflicting jobs cannot be scheduled simultaneously on different machines. In the context of our study, these conflicts are modelled by general graphs. The problem of minimising the maximum completion time (makespan) is known to be NP-hard in the strong sense. We propose a mixed-integer linear programming (MILP) model. Then, we develop a branch and bound algorithm based on new lower and upper bound procedures. We further provide a computer simulation to measure the performance of the proposed approaches. The computational results show that the branch and bound algorithm outperforms the MILP model and can solve instances of size up to 20,000 jobs.

关键词： scheduling flow shop conflict graph mixed-integer linear programming branch and bound

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Modelling and optimising the marginal expansion of an existing district heating network

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ENERGY 2017年第Part1期140卷 209-223页

作者： Delangle, Axelle Lambert, Romain S. C. Shah, Nilay Acha, Salvador Markides, Christos N. Imperial Coll London Ctr Proc Syst Engn Dept Chem Engn South Kensington Campus London SW7 2AZ England

Although district heating networks have a key role to play in tackling greenhouse gas emissions associated with urban energy systems, little work has been carried out on district heating networks expansion in the literature. The present article develops a methodology to find the best district heating network expansion strategy under a set of given constraints. Using a mixed-integer linear programming approach, the model developed optimises the future energy centre operation by selecting the best mix of technologies to achieve a given purpose (e.g. cost savings maximisation or greenhouse gas emissions minimisation). Spatial expansion features are also considered in the methodology. Applied to a case study, the model demonstrates that depending on the optimisation performed, some building connection strategies have to be prioritised. Outputs also prove that district heating schemes' financial viability may be affected by the connection scenario chosen, highlighting the necessity of planning strategies for district heating networks. The proposed approach is highly flexible as it can be adapted to other district heating network schemes and modified to integrate more aspects and constraints. (C) 2017 The Authors. Published by Elsevier Ltd.

关键词： District heating network expansion mixed-integer linear programming Investment schedule Low carbon heat

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Heuristic approach for the economic optimisation of combined heat and power (CHP) plants: Operating strategy, heat storage and power

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ENERGY 2017年 121卷 66-77页

作者： Vogelin, Philipp Koch, Ben Georges, Gil Boulouchos, Konstatinos Swiss Fed Inst Technol Aerothermochem & Combust Syst Lab Sonneggstr 3 CH-8092 Zurich Switzerland

CHP plants produce power and heat in parallel and operate between power and heat consumers as well as prices for their supply. The profitability of a plant with given power depends on operating strategy and heat storage size. In this paper, we present a fast heuristic algorithm to determine the most profitable setting for given boundary conditions, as a substitute for the state-of-the-art approach based on mixed integer linear programming (MILP). The presented heuristic algorithm is appropriate for thousands of plant calculations or real-time operation planning of single as well as interconnected plants. We used hourly resolved full-year data reflecting electricity market price and heat demand, which was simulated using a typical multi-family house configuration. The heuristic algorithm found the optimal operating strategy and heat storage size 34 times faster than the M1LP solver. Additional optimisation runs of the operating pattern at various fixed heat storage sizes, resulted in equal solutions of both approaches. The heuristic algorithm found in this case the operating patterns around 200 times faster. Furthermore, the heuristic algorithm can be enhanced to find optimal CHP power, heat storage size and operating strategy in one process using characteristic curves for plant efficiencies and costs. (C) 2017 Elsevier Ltd. All rights reserved.

关键词： Combined heat and power Thermal energy storage Economic optimisation Heuristic algorithm mixed-integer linear programming Building heat demand

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Two-Stage Adaptive Restoration Decision Support System for a Self-Healing Power Grid

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IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS 2017年第6期13卷 2802-2812页

作者： Golshani, Amir Sun, Wei Zhou, Qun Zheng, Qipeng P. Tong, Jianzhong Univ Cent Florida Dept Elect & Comp Engn Orlando FL 32816 USA Univ Cent Florida Dept Ind Engn & Management Syst Orlando FL 32816 USA PJM Interconnect LLC Audubon PA 19403 USA

Power outages cost American industries and businesses billions of dollars and jeopardize the lives of hospital patients. The losses can be greatly reduced with a fast, reliable, and flexible self-healing tool. This paper is aimed to tackle the challenging task of developing an adaptive restoration decision support system (RDSS). The proposed RDSS determines restoration actions both in planning and real-time phases and adapts to constantly changing system conditions. The comprehensive formulation encompasses practical constraints including ac power flow, dynamic reserve, and load modeling. The combinatorial problem is decomposed into a two-stage formulation solved by an integer L-shaped algorithm. The two stages are then executed online in the RDSS framework employing a sliding window method. The IEEE 39-bus system has been studied under normal and contingency conditions to demonstrate the effectiveness and efficiency of the proposed online RDSS.

关键词： Adaptive restoration dynamic reserve integer L-shaped algorithm mixed-integer linear programming two-stage optimization

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MILP models and metaheuristic for balancing and sequencing of mixed-model two-sided assembly lines

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EUROPEAN JOURNAL OF INDUSTRIAL ENGINEERING 2017年第3期11卷 353-379页

作者： Nilakantan, J. Mukund Li, Zixiang Tang, Qiuhua Nielsen, Peter Aalborg Univ Dept Mat & Prod Aalborg Denmark Wuhan Univ Sci & Technol Ind Engn Dept Wuhan 430081 Hubei Peoples R China

mixed-model assembly lines are becoming increasingly popular due to flexibility of producing customised products. In a mixed-model assembly line, line balancing and model sequencing problems are tightly interrelated and very important for efficiency. This paper proposes a new assembly line configuration based on paced mixed-model two-sided assembly lines where balancing and sequencing problems are considered simultaneously. Minimal work has been reported considering both problems simultaneously for this type of assembly line configuration. Two mixed-integer linear programming (MILP) models are developed and a restarted SA algorithm with new encoding, decoding and neighbourhood procedures is developed. The parameters of the proposed algorithm are selected based on a statistical technique and the performance of it is tested on a set of new benchmark problems. The computational results demonstrate the effectiveness of the MILP models and the high efficiency of the proposed algorithm. The proposed algorithm outperforms the comparative original SA algorithm.

关键词： assembly line balancing model sequencing mixed-model two-sided assembly line mixed-integer linear programming MILP simulated annealing

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On handling indicator constraints in mixed integer programming

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COMPUTATIONAL OPTIMIZATION AND APPLICATIONS 2016年第3期65卷 545-566页

作者： Belotti, Pietro Bonami, Pierre Fischetti, Matteo Lodi, Andrea Monaci, Michele Nogales-Gomez, Amaya Salvagnin, Domenico FICO Birmingham W Midlands England IBM Corp Madrid Spain Univ Padua Padua Italy Univ Bologna Bologna Italy Ecole Polytech Montreal Montreal PQ Canada Huawei France R&D Math & Algorithm Sci Lab Paris France IBM Corp Milan Italy

mixed integer programming (MIP) is commonly used to model indicator constraints, i.e., constraints that either hold or are relaxed depending on the value of a binary variable. Unfortunately, those models tend to lead to weak continuous relaxations and turn out to be unsolvable in practice;this is what happens, for e.g., in the case of Classification problems with Ramp Loss functions that represent an important application in this context. In this paper we show the computational evidence that a relevant class of these Classification instances can be solved far more efficiently if a nonlinear, nonconvex reformulation of the indicator constraints is used instead of the linear one. Inspired by this empirical and surprising observation, we show that aggressive bound tightening is the crucial ingredient for solving this class of instances, and we devise a pair of computationally effective algorithmic approaches that exploit it within MIP. One of these methods is currently part of the arsenal of IBM-Cplex since version 12.6.1. More generally, we argue that aggressive bound tightening is often overlooked in MIP, while it represents a significant building block for enhancing MIP technology when indicator constraints and disjunctive terms are present.

关键词： mixed-integer linear programming mixed-integer quadratic programming Indicator constraints

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Non-prespecified Starting Depot Formulations for Minimum-Distance Trajectory Optimization in Patrolling Problem

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JOURNAL OF INTELLIGENT & ROBOTIC SYSTEMS 2017年第3-4期87卷 699-710页

作者： Ghadiry, Walaaeldin Habibi, Jalal Aghdam, Amir G. Zhang, Youmin Concordia Univ Dept Elect & Comp Engn Montreal PQ Canada McGill Univ Fac Engn Montreal PQ Canada Concordia Univ Dept Mech & Ind Engn Montreal PQ Canada

In this paper, two new formulations are presented for trajectory optimization in the patrolling problem. It is assumed that the starting depot is not prespecified;an assumption that distinguishes the present work from the existing literature. A number of viewpoints are assigned to be visited in a certain sequence to minimize the total travel distance. The problem turns out to be a variant of the well-known Traveling Salesmen Problem (TSP), namely the Single depot multiple Traveling Salesmen Problem (mTSP). Comparisons between the commonly-used prespecified starting depot approach and the proposed formulations are performed and the efficacy of the results is presented through simulations. It is noted that by using the new approach, the total travel distance can be improved by an average of about 20 % compared to the case where the starting depot is prespecified, and by about 40 % in the worst-case scenario (in terms of the starting depot).

关键词： Single depot multiple Travelling Salesman problem (mTSP) Patrolling problem Non-prespecified starting depot Return trip mixed-integer linear programming

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