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Voltage Stability Analysis in Medium-Voltage Distribution Networks Using a second-order cone Approximation

ENERGIES 2020年第21期13卷 5717页

作者： Danilo Montoya, Oscar Gil-Gonzalez, Walter Arias-Londono, Andres Rajagopalan, Arul Hernandez, Jesus C. Univ Dist Francisco Jose de Caldas Fac Ingn Bogota 11021 Colombia Univ Tecnol Bolivar Lab Inteligente Energia Cartagena 131001 Colombia Inst Univ Pascual Bravo Fac Ingn Campus Robledo Medellin 050036 Colombia Vellore Inst Technol Sch Elect Engn Chennai 632014 Tamil Nadu India Univ Jaen Dept Elect Engn Campus Lagunillas S-NEdificio A3 Jaen 23071 Spain

This paper addresses the voltage stability margin calculation in medium-voltage distribution networks in the context of exact mathematical modeling. This margin calculation is performed with a second-order cone (SOCP) reformulation of the classical nonlinear non-convex optimal power flow problems. The main idea around the SOCP approximation is to guarantee the global optimal solution via convex optimization, considering as the objective function the lambda-coefficient associated with the maximum possible increment of the load consumption at all the nodes. Different simulation cases are considered in one test feeder, described as follows: (i) the distribution network without penetration of distributed generation;(ii) the distribution network with penetration of distributed generation;and (iii) the distribution grid with capacitive compensation. Numerical results in the test system demonstrated the effectiveness of the proposed SOCP approximation to determine the lambda-coefficient. In addition, the proposed approximation is compared with nonlinear tools available in the literature. All the simulations are carried out in the MATLAB software with the CVX package and the Gurobi solver.

关键词： second order cone programming voltage stability analysis optimal power flow model convex optimization

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Solution methods for a min-max facility location problem with regional customers considering closest Euclidean distances

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COMPUTATIONAL OPTIMIZATION AND APPLICATIONS 2020年第2期75卷 537-560页

作者： Dolu, Nazli Hasturk, Umur Tural, Mustafa Kemal Middle East Tech Univ Dept Ind Engn Ankara Turkey

We study a facility location problem where a single facility serves multiple customers each represented by a (possibly non-convex) region in the plane. The aim of the problem is to locate a single facility in the plane so that the maximum of the closest Euclidean distances between the facility and the customer regions is minimized. Assuming that each customer region is mixed-integer second order cone representable, we firstly give a mixed-integer second order cone programming formulation of the problem. secondly, we consider a solution method based on the Minkowski sums of sets. Both of these solution methods are extended to the constrained case in which the facility is to be located on a (possibly non-convex) subset of the plane. Finally, these two methods are compared in terms of solution quality and time with extensive computational experiments.

关键词： Facility location Min-max problem second order cone programming Minkowski sum Regional customer

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A Bi-Level Corrective Line Switching Model for Urban Power Grid Congestion Mitigation

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IEEE TRANSACTIONS ON POWER SYSTEMS 2020年第4期35卷 2959-2970页

作者： Zhang, Xi Liu, Youbo Gao, Hongjun Wang, Lingfeng Liu, Junyong Sichuan Univ Coll Elect Engn & Informat Technol Chengdu 610065 Peoples R China Univ Wisconsin Dept Elect Engn & Comp Sci Milwaukee WI 53211 USA

The fast urbanization process in developing countries creates an electricity load surge that poses serious congestion problems to the urban power grid (UPG). The current practice of system operators is to reconfigure the topological structure of the 110-kV high voltage distribution network (HVDN) in an attempt to adjust the load distribution and eliminate the UPG congestion. However, HVDN reconfiguration is a large scale, non-convex and non-linear optimization problem that is intractable to be solved in an efficient manner. In order to reduce the computing cost and overcome the difficulty in the solving process, new partition rules are proposed to divide the HVDN into multiple smaller regions. The topological structure of each region can be optimized either independently or interdependently based on the condition of the UPG. The solving process is modeled as a bi-level iterative line switching problem. At the upper level, the operational boundary (OB) of each regional HVDN is calculated based on a set of convex ACOPF constraints. At the lower level, the line switching scheme of each regional HVDN is derived based on the corresponding mixed integer second-order cone programming (MISOCP) model considering the OB. Then, the line switching result is examined by the AC power flow to identify whether there is any violation or not. This iterative process continues until all the violations are corrected in the UPG. The proposed method was validated by a modified IEEE 58-node test system and a practical 157-node UPG system. The simulation results showed that the proposed method is able to achieve a higher computational efficiency than the traditional method so it is promising for online applications.

关键词： Switches Substations Load flow Mathematical model Power grids Reactive power Transmission congestion management high voltage distribution network (HVDN) line switching transmission and distribution interactions second order cone programming

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A stabilized iRBF mesh-free method for quasi-lower bound shakedown analysis of structures

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COMPUTERS & STRUCTURES 2020年 228卷 1页

作者： Ho, Phuc L. H. Le, Canh, V Int Univ VNU HCMC Dept Civil Engn Ho Chi Minh City Vietnam HCMC Univ Technol & Educ Fac Civil Engn Ho Chi Minh City Vietnam

This paper presents a quasi-static formulation, based on integrated radial basis functions (iRBF) and conic programming, for direct analysis of 2D and 3D structures. The iRBF shape functions are stabilized using stabilized conforming nodal integration (SCNI) technique. Equilibrium equations, boundary conditions and yield criterion associated with the residual stresses are directly enforced at scattered nodes without any special treatment. The safety load multipliers are determined by solving the conic optimization problems resulting from static shakedown theorem. The computation cost in terms of the number of variables and optimization CPU time is kept to a minimum. Various benchmark problems in two and three dimensions are investigated, showing the efficiency of the presented numerical approach. (C) 2019 Elsevier Ltd. All rights reserved.

关键词： Integrated radial basis function Mesh-free method Limit and shakedown analysis second order cone programming

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Connectivity Maintenance in Mobile Networks

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IEEE-ACM TRANSACTIONS ON NETWORKING 2020年第3期28卷 1269-1282页

作者： Ding, Kai Yousefi'zadeh, Homayoun Jabbari, Faryar Univ Calif Irvine Dept Mech & Aerosp Engn Irvine CA 92697 USA Univ Calif Irvine Ctr Pervas Commun & Comp Dept Elect Engn & Comp Sci Irvine CA 92697 USA

This work studies connectivity maintenance of mobile networks. A mobile network of interest consists of two types of nodes, pre-deployed (client) and intermediate nodes. Upon initial deployment of client nodes in a field, multiple stationary intermediate nodes are placed strategically to establish robust network connectivity. We study scenarios in which an initially connected network consisting of pre-deployed and intermediate nodes is exposed to mobility of the former. Two types of node mobility scenarios are investigated. The first scenario analyzes the bounds of mobility when pre-deployed nodes move at small scales. The bounds of node mobility preserving connectivity are derived through analysis and verified by simulations. The second scenario considers the movement of pre-deployed nodes beyond the bounds of the first scenario thereby breaking connected links and partitioning the connected network. This scenario then considers relocating the existing intermediate nodes in order to reestablish connectivity. A general formulation is proposed in the form of an optimization problem. We prove that the general formulation of the problem is NP-hard. Next, we turn our attention to a practical scenario in which the location of nodes is made available using GPS signals. We solve the problem of practical scenario in polynomial time and analyze the complexity of our solution. We also present comprehensive performance evaluation results of our proposed algorithm.

关键词： Safety Maintenance engineering Logic gates Standards Optimization IEEE transactions Global Positioning System Connectivity maintenance hexagonal coordinate system small scale mobility large scale mobility Laplacian matrix mixed integer semi-definite programming location awareness second order cone programming algebraic graph theory

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Additive slacks-based measure: Computational strategy and extension to network DEA

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OMEGA-INTERNATIONAL JOURNAL OF MANAGEMENT SCIENCE 2020年 91卷 102022-000页

作者： Chen, Kun Zhu, Joe Nanjing Audit Univ Coll Auditing & Evaluat Nanjing 211815 Jiangsu Peoples R China Worcester Polytech Inst Foisie Business Sch Worcester MA 01609 USA

The current paper visits a set of data envelopment analysis (DEA) models that identify inefficiency by optimizing input and output slacks. These slacks are aggregated either in an additive or ratio form. Only the ratio slacks-based DEA models can be solved as a linear program and generate a DEA score between zero and unity. The additive slacks-based model can be equivalent to the Russell graph measure and converted into a second order cone programming (SOCP) problem whose solving procedure has become a mature technology. As such, the additive slacks-based model can also yield a DEA score between zero and unity. This study shows that the additive slacks-based model can be applied to modelling network DEA where the internal structures of decision making units (DMUs) are of interest. The additive slacks-based network DEA can be solved using SOCP technique and adapted to the preference of the decision maker by choosing the weights for aggregating individual components in the network structures. It is shown that the additive slacks-based approach can yield divisional efficiencies of Pareto optimal equivalences to be selected by the decision maker when compared to the existing ratio slacks-based measure. An example and solving codes are provided in the current study. (C) 2018 Elsevier Ltd. All rights reserved.

关键词： Data envelopment analysis (DEA) Additive slacks-based measure Russell measure second order cone programming Network DEA

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A robust least square approach for forecasting models: an application to Brazil's natural gas demand

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ENERGY SYSTEMS-OPTIMIZATION MODELING SIMULATION AND ECONOMIC ASPECTS 2020年第4期11卷 1111-1135页

作者： Costa, Oswaldo L. V. de Oliveira Ribeiro, Celma Ho, Linda Lee Rego, Erik Eduardo Parente, Virginia Toro, Javier Univ Sao Paulo EPUSP Polytech Sch Dept Telecommun & Control Engn Sao Paulo Brazil EPUSP Dept Prod Engn Sao Paulo Brazil Univ Sao Paulo Inst Energy & Environm Grad Energy Program Sao Paulo Brazil

The robust least square method has been introduced in the literature as a new parameter estimation technique to deal with the presence of data uncertainties. In this paper we propose to use the robust least square method combined with log-linear Cobb-Douglas model as an alternative for developing forecast models. We first extend the robust least square method to the case which allows uncertainties only in some columns of the data matrix as well as to include weighting matrices on the past data observations and on the uncertainties. Afterwards we compare the robust and ordinary least square methods for the yearly estimate for the natural gas demand in Brazil, considering the total demand as well as the industrial and power sectors demand. Regarding the power sector case, a further contribution of the paper is to analyze the impact of the reservoirs' levels over the demand of natural gas by thermoelectric power plants in an energy mix dominated by hydropower. Although both methods, the robust and the ordinary least square, presented similar results, the robust approach gave a slightly better result and presented reasonable long-run elasticities related to the demand of natural in the country, indicating that can it be a good alternative to overcome the difficulties associated with the use of short time series and unreliable data on the forecast of energy consumption in emerging markets.

关键词： Robust least square second order cone programming Demand forecast Natural gas in Brazil

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Three-dimensional face stability analysis of shallow tunnels using numerical limit analysis and material point method

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TUNNELLING AND UNDERGROUND SPACE TECHNOLOGY 2021年 112卷 103904-103904页

作者： Fernandez, Fabricio Rojas, Jhonatan E. G. Vargas Jr, Euripedes A. Velloso, Raquel Q. Dias, Daniel Pontificia Univ Catolica Rio de Janeiro Rio De Janeiro RJ Brazil Antea Grp Antony France Univ Grenoble Alpes 3SR Grenoble INP CNRS F-38000 Grenoble France

In this work, the collapse conditions of shallow tunnel faces are studied using the Numerical Limit Analysis (NLA) and the Material Point Method (MPM). A particular form (based on a mixed representation of velocities and stresses) of the lower bound formulation of numerical limit analysis was used. The solution using NLA is evaluated considering finite elements for the volume discretization in conjunction with the second order cone and semidefinite programming methodologies. Drucker-Prager and Mohr-Coulomb failure criteria have been used. In the case of MPM, the continuum media is discretized by a set of material points which store all the relevant properties and variables such as mass, stress, velocity, and energy. The objective of this paper is to evaluate the characteristics of both methods when applied to the determination of the tunnel face stability conditions of shallow tunnels, in particular to the determination of failure mechanisms and run-out analysis of the failed mass. Results obtained from experiments on a small-scale model (Sterpi et al., 1996) are used as a reference for the study. The results obtained showed that both MPM and NLA can predict the global failure mechanism and the minimum tunnel face pressure required for stability.

关键词： Tunnel face stability Numerical limit analysis second order cone programming Material point method

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Bicriteria scheduling of a material handling robot in an m-machine cell to minimize the energy consumption of the robot and the cycle time

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ROBOTICS AND COMPUTER-INTEGRATED MANUFACTURING 2021年 72卷 1页

作者： Gultekin, Hakan Gurel, Sinan Taspinar, Rabia Sultan Qaboos Univ Dept Mech & Ind Engn Muscat Oman TOBB Univ Econ & Technol Dept Ind Engn Ankara Turkey Middle East Tech Univ Ind Engn Dept Ankara Turkey Sabanci Univ Dept Ind Engn Istanbul Turkey

This study considers a flowshop type production system consisting of m machines. A material handling robot transports the parts between the machines and loads and unloads the machines. We consider the sequencing of the robot moves and determining the speeds of these moves simultaneously. These decisions affect both the robot's energy consumption and the production speed of the system. In this study, these two objectives are considered simultaneously. We propose a second order cone programming formulation to find Pareto efficient solutions. We also develop a heuristic algorithm that finds a set of approximate Pareto efficient solutions. The conic formulation can find robot schedules for small cells with less number of machines in reasonable computation times. Our heuristic algorithm can generate a large set of approximate Pareto efficient solutions in a very short computational time. Proposed solution approaches help the decision-maker to achieve the best trade-off between the throughput of a cell and the energy efficiency of a material handling robot.

关键词： Bicriteria scheduling Robotic cell Energy consumption Robot speed control second order cone programming

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You gain when you give: Constructing a sustainable development model for world heritage sites

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JOURNAL OF CLEANER PRODUCTION 2021年 328卷 129547-129547页

作者： Wang, Shi-Xiao Lu, Wen-Min Hung, Shiu-Wan Guangdong Univ Finance & Econ Sch Business Adm Guangzhou Peoples R China Chinese Culture Univ Dept Int Business Adm Taipei Taiwan Natl Cent Univ Dept Business Adm Taipei Taiwan

The importance of preserving world heritage sites (WHS) has been recognized worldwide. WHS are still damaged in many developing countries, who insist that preserving lead to poor economic development. There is a dispute between ecological protection and economic growth. Scholars proposed sustainable development to resolve the dispute. However, the result of sustainable development could not be well evaluated by previous studies. The relationship between ecological protection and economic growth was still unknown. The research object of this study is to construct a two-stage model of sustainable development to deal with the dilemma between ecological and economic goals. The relationship between ecological protection and economic development will be verified. It is found that heritage sites could be protected by proper activities that contribute to economic development. Strict ecological protection brings a sound ecological environment, which, in turn, creates a positive image important for attracting arrivals. The innovation of this study is to propose a two-stage network DEA method with second order cone programming technique to examine the sustainable development. A performance improvement strategy map would be provided to promote the sustainable performance for WHS in different countries.

关键词： Sustainable operations World heritage sites Multiplicative efficiency aggregation second order cone programming

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