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An MISOCP-Based Solution Approach to the Reactive Optimal Power Flow Problem

IEEE TRANSACTIONS ON POWER SYSTEMS 2021年第1期36卷 529-532页

作者： Kayacik, Sezen Ece Kocuk, Burak Sabanci Univ Ind Engn Program TR-34956 Istanbul Turkey

In this letter, we present an alternative mixed-integer non-linear programming formulation of the reactive optimal power flow (ROPF) problem. We utilize a mixed-integer second-order cone programming (MISOCP) based approach to find global optimal solutions of the proposed ROPF problem formulation. We strengthen the MISOCP relaxation via the addition of convex envelopes and cutting planes. Computational experiments on challenging test cases show that the MISOCP-based approach yields promising results compared to a semidefinite programming based approach from the literature.

关键词： mixed-integer non-linear programming reactive optimal power flow second-order cone programming

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Flow shop scheduling problem with non-linear learning effects: A linear approximation scheme for non-technical users

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JOURNAL OF COMPUTATIONAL AND APPLIED MATHEMATICS 2023年第1期424卷

作者： Ferraro, Augusto Rossit, Daniel Alejandro Toncovich, Adrian Univ Nacl Sur Engn Dept Ave Alem 1253 RA-8000 Bahia Blanca Buenos Aires Argentina Consejo Nacl Invest Cient & Tecn INMABB Ave Alem 1253 RA-8000 Bahia Blanca Buenos Aires Argentina

Scheduling problems with learning effect have taken a renewed interest in recent years due to increasingly personalized productions, leveraged by the capabilities provided by Industry 4.0. In this work, a learning effect problem described by an exponential curve proportional to the accumulated processing time in a flow shop type configuration was addressed. The objective to be minimized is the makespan. This problem is non-linear, which prevents it from being addressed by standard software such as spreadsheets and commercial MILP solvers. For overcoming this issue a linear approximation approach is proposed. This linear approximation approach consists in representing the exponential curve by a set of piecewise smooth lines.. The parameterization of the piecewise smooth line can be solved with spreadsheet tools, using probabilistic models that implicitly provide information about the difficulty of modeling an exponential curve by means of straight lines. Then, a MILP model was generated based on this approximation scheme, which can be solved by standard solvers such as CPLEX or Gurobi. In turn, the problem was also modeled in its MINLP format, and it was solved with a state-of-the-art MINLP solver. The results show the improvement of the linear approximation solution with respect to the MINLP solution, where improvements greater than 10% are achieved in terms of makespan.(c) 2022 Elsevier B.V. All rights reserved.

关键词： Flow shop scheduling Learning effect mixed-integer non-linear programming Makespan linear approximation

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Unequal-area capability-based facility layout design problem with a heuristic decomposition-based iterative mathematical programming approach

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EXPERT SYSTEMS WITH APPLICATIONS 2023年 214卷

作者： Subulan, Kemal Varol, Bilge Baykasoglu, Adil Dokuz Eylul Univ Dept Ind Engn Fac Engn Izmir Turkiye Dokuz Eylul Univ Grad Sch Nat & Appl Sci Izmir Turkiye

Thus far in the available literature, capability-based facility layout design approaches were developed by only considering equal machine areas, where they are assigned to the pre-specified locations. Based on this motivation, this paper introduces a new unequal-area capability-based facility layout design (UA-CBFLD) problem for the first time in the literature. In addition to the machines' unequal-area requirements, the proper distribution of their processing capabilities over the shop floor is considered. First, a new mixed-integer non-linear programming (MINLP) model is developed. Then, a polyhedral inner-approximation method is applied to cope with nonlinear area constraints. Due to its NP-hard nature and highly non-linear structure, a heuristic decompositionbased iterative solution approach is also proposed to solve realistic size problems within a reasonable time. In order to show the validity and applicability of the proposed approach, both an illustrative example with different machine-capability overlaps and a real-life application in a manufacturing company are presented. The computational results have shown that the proposed approach has found a 33.25% better layout score (as a function of the distance and the amounts of product flows) and achieved this solution 116.64% faster than the solution of the developed MINLP model via Gurobi's standard non-linear programming solver. Furthermore, when compared to the existing cellular facility layout design of the manufacturing company, the proposed capability-based unequal-area layout design option has also 29.37% and 34.74% superior layout scores under the scenarios of equal and unequal machine areas, respectively. Moreover, the total average machine utilization has increased up to 89.6%, which is comparatively better than the current average cell utilization, i.e., 65.2%.

关键词： UA-FLP Capability-based layout design Inner-approximation method mixed-integer non-linear programming Heuristic decomposition-based approach

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A bidding mechanism for maintenance of generation units considering inter-ISO power exchange

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INTERNATIONAL JOURNAL OF ELECTRICAL POWER & ENERGY SYSTEMS 2023年 144卷

作者： Fu, Jianfeng Nunez, Alfredo De Schutter, Bart Delft Univ Technol Delft Ctr Syst & Control Delft Netherlands Delft Univ Technol Dept Engn Struct Delft Netherlands

To ensure the reliability of power systems, the independent system operator (ISO) manages the planning process of the maintenance of generation units for generation companies (GENCOs). This paper focuses on a widely studied two-layer long-term predictive maintenance decision making framework in a deregulated environment. In the first layer the ISO-wide maintenance schedule is optimized for the GENCOs, targeting minimal total maintenance cost and degradation statuses. In the second layer, a bidding mechanism is designed for GENCOs who are not satisfied with the time slots scheduled by the first layer, so that they can bid for their preferred time slots. A novel bidding mechanism for the host ISO (i.e., the ISO that manages the maintenance planning process) is proposed, called interchangeable bidding mechanism for maintenance (IBMM). In this mechanism, the GENCOs of the host ISO can use their bid price to purchase the supportive energy from the GENCOs of the neighbor ISOs. Furthermore, they also can pay a penalty fee for reducing the amount of energy transmitted from the host ISO to the neighbor ISO with respect to what has been stipulated in the long-term inter-ISO power exchange contract. IBMM provides more opportunities for GENCOs of the host ISO to obtain their preferred maintenance time slots. Additionally, the power system reliability can be ensured. IBMM is formulated as a mixed-integer non-linear bidding programming problem. Then, the bidding programming problem is recast into a mixed-integer second-order cone programming (MISOCP) problem that can be solved using Gurobi. In the case study, the IEEE 118-bus network is studied to illustrate the performance of the proposed bidding strategy.

关键词： Generation unit maintenance Maintenance bidding mechanism mixed-integer non-linear programming problem Inter-ISO energy exchange

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Optimal Design and Competitive Spans of Timber Floor Joists Based on Multi-Parametric MINLP Optimization

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MATERIALS 2022年第9期15卷 3217页

作者： Jelusi, Primoz Kravanja, Stojan Univ Maribor Fac Civil Engn Transportat Engn & Architecture Smetanova Ulica 17 Maribor 2000 Slovenia

This study investigates the optimization of the design of timber floor joists, taking into account the self-manufacturing costs and the discrete sizes of the structure. This non-linear and discrete class of optimization problem was solved with the multi-parametric mixed-integer non-linear programming (MINLP). An MINLP optimization model was developed. In the model, an accurate objective function of the material and labor costs of the structure was subjected to design, strength, vibration and deflection (in)equality constraints, defined according to Eurocode regulations. The optimal design of timber floor joists was investigated for different floor systems, different materials (sawn wood and glulam), different load sharing systems, different vertical imposed loads, different spans, and different alternatives of discrete cross-sections. For the above parameters, 380 individual MINLP optimizations were performed. Based on the results obtained, a recommended optimal design for timber floor joists was developed. Engineers can select from the recommendations the optimal design system for a given imposed load and span of the structure. Economically suitable spans for timber floor joists structures were found. The current knowledge of competitive spans for timber floor joists is extended based on cost optimization and Eurocode standards.

关键词： structural optimization cost optimization discrete optimization mixed-integer non-linear programming MINLP timber floor joists

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Reducing committed emissions of heating towards 2050: Analysis of scenarios for the insulation of buildings and the decarbonisation of electricity generation

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APPLIED ENERGY 2022年 325卷

作者： Kaandorp, Chelsea Miedema, Tes Verhagen, Jeroen van de Giesen, Nick Abraham, Edo Delft Univ Technol Fac Civil Engn & Geosci Dept Water Management Stevinweg 1 NL-2628 CN Delft Netherlands

Infrastructure for heat provision in the built environment needs to change remarkably to support lowering carbon emissions and achieving climate mitigation targets before 2050. We propose a computational approach for finding a mix of heat options per neighbourhood that minimises cumulative carbon emissions between 2030 and 2050, referred to as committed emissions, while at the same time adhering to technological constraints at both the household and neighbourhood scales. To establish this approach, we integrated bottom -up heat demand modelling at neighbourhood scale with a mixed-integer non-linear optimisation problem. Nine scenarios with different pathways for the insulation of buildings and the decarbonisation in electricity generation were considered and applied to three neighbourhoods in the city of Amsterdam, the Netherlands. The results show that (i) the committed emissions are ten times lower between 2030 and 2050 in scenarios in which ambitious measures are taken for the insulation of buildings and the decarbonisation in electricity generation, (ii) only in these 'ambitious scenarios' low temperature heat systems, such as heat pumps and low temperature heat networks, are optimal solutions for minimising committed emissions, (iii) if less ambitious insulation and decarbonisation measures are taken, high temperature heat options can be part of the heat mix with lowest committed emissions, and (iv) the minimum heat density for low temperature heat networks is not always achieved, creating risks for carbon lock-ins when applying these heat networks. Our results clearly indicate that pathways for the retrofitting of buildings and the decarbonisation in electricity generation need to be taken into account jointly when designing renewable and low-carbon heat systems to optimally reduce carbon emissions towards 2050 and reduce future carbon lock-ins.

关键词： Urban heat systems Committed carbon emissions Retro-fitting of the building stock Electrification of heating Carbon lock-in mixed-integer non-linear programming

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Optimal design of heat pump integrated low-grade heat utilization systems

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ENERGY CONVERSION AND MANAGEMENT 2022年 260卷 1页

作者： Hu, Jianqing Fan, Shanshan Zhang, Bingjian He, Chang Liu, Zuming Chen, Qinglin Sun Yat Sen Univ Guangdong Engn Ctr Petrochem Energy Conservat Sch Mat Sci & Engn Guangzhou 510275 Guangdong Peoples R China Sun Yat Sen Univ Sch Chem Engn & Technol Zhuhai 519082 Guangdong Peoples R China Shanghai Jiao Tong Univ Coll Smart Energy Shanghai 200240 Peoples R China

Recovery and utilization of low-grade heat in the process industries offers considerable economic and environmental benefits. Low-grade heat utilization employs circulating medium for heat transfer between heat sources and sinks. Thus, it is in need to synchronously integrate heat sources, circulating medium and heat sinks. It is extremely challenging for optimal design of low-grade heat utilization systems (LHUS) when considering quantity and quality of heat sources, heat sink requirements, feasible integration technologies and economic performance simultaneously. The current design methods for low-grade heat utilization integrated with upgrading technologies are simplified, narrowing down their integration domain. In this work, integration strategy of LHUS with heat pump technology is first proposed. A novel methodology for optimal design of heat pump integrated low-grade heat utilization systems (HPiLHUS) is developed subsequently for implementing the integration strategy. A modified superstructure characterized by nodes, low-low pressure steam (LLPS) generation module and a heat pump system is presented. The node acts as mixer, splitter or heat exchanger, and thus enables HPiLHUS optimization in all feasible domain. The LLPS generation module provides a promising integration possibility for heat pump technology. The heat pump system aims to upgrade low-grade heat in order to improve energy utilization efficiency. A mixed-integer non-linear programming (MINLP) model is formulated for optimal design of LHUS/HPiLHUS. Real-world case studies are employed to demonstrate our method's efficacy and applicability. The results show that integration of heat pump technology with LHUS reduces total annual cost (TAC) by 12.2%, demonstrating huge potential for reduction of energy consumption. Scenario analysis exhibit the advantages of our proposed modified method over conventional methods. Sensitivity analysis shows LLPS generation temperature and excavated heat sink duty hav

关键词： Low-grade heat utilization Heat pump Low-low pressure steam generation Heat exchange networks mixed-integer non-linear programming

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Joint Antenna Placement and Power Allocation for Target Detection in a Distributed MIMO Radar Network

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REMOTE SENSING 2022年第11期14卷 2650页

作者： Qi, Cheng Xie, Junwei Zhang, Haowei Air Force Engn Univ Air & Missile Def Coll Xian 710051 Peoples R China

Radar network configuration and power allocation are of great importance in military applications, where the entire surveillance area needs to be searched under resource budget constraints. To pursue the joint antenna placement and power allocation (JAPPA) optimization, this paper develops a JAPPA strategy to improve target detection performance in a widely distributed multiple-input and multiple-output (MIMO) radar network. First, the three variables of the problem are incorporated into the Neyman-Pearson (NP) detector by using the antenna placement optimization and the Lagrange power allocation method. Further, an improved iterative greedy dropping heuristic method based on a two-stage local search is proposed to solve the NP-hard issues of high-dimensional non-linear integer programming. Then, the sum of the weighted logarithmic likelihood ratio test (LRT) function is constructed as optimization criteria for the JAPPA approach. Numerical simulations and the theoretical analysis confirm the superiority of the proposed algorithm in terms of achieving effective overall detection performance.

关键词： antennas placement convex optimization distributed MIMO radar mixed-integer non-linear programming power allocation target detection

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Efficient Operations of Micro-Grids with Meshed Topology and Under Uncertainty through Exact Satisfaction of AC-PF, Droop Control and Tap-Changer Constraints

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ENERGIES 2022年第10期15卷 3662页

作者： Bragin, Mikhail A. Yan, Bing Kumar, Akash Yu, Nanpeng Zhang, Peng Univ Connecticut Dept Elect & Comp Engn Storrs CT 06269 USA Rochester Inst Technol Dept Elect & Microelect Engn Rochester NY 14623 USA Univ Calif Riverside Dept Elect & Comp Engn Riverside CA 94143 USA SUNY Stony Brook Dept Elect & Comp Engn Stony Brook NY 11794 USA

Micro-grids' operations offer local reliability;in the event of faults or low voltage/frequency events on the utility side, micro-grids can disconnect from the main grid and operate autonomously while providing a continued supply of power to local customers. With the ever-increasing penetration of renewable generation, however, operations of micro-grids become increasingly complicated because of the associated fluctuations of voltages. As a result, transformer taps are adjusted frequently, thereby leading to fast degradation of expensive tap-changer transformers. In the islanding mode, the difficulties also come from the drop in voltage and frequency upon disconnecting from the main grid. To appropriately model the above, non-linear AC power flow constraints are necessary. Computationally, the discrete nature of tap-changer operations and the stochasticity caused by renewables add two layers of difficulty on top of a complicated AC-OPF problem. To resolve the above computational difficulties, the main principles of the recently developed "l(1)-proximal" Surrogate Lagrangian Relaxation are extended. Testing results based on the nine-bus system demonstrate the efficiency of the method to obtain the exact feasible solutions for micro-grid operations, thereby avoiding approximations inherent to existing methods;in particular, fast convergence of the method to feasible solutions is demonstrated. It is also demonstrated that through the optimization, the number of tap changes is drastically reduced, and the method is capable of efficiently handling networks with meshed topologies.

关键词： micro-grids droop controls tap changers islanded mode AC OPF Lagrangian relaxation renewable generation Markov process mixed-integer non-linear programming

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Bi-objective design-for-control for improving the pressure management and resilience of water distribution networks

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WATER RESEARCH 2022年 222卷 118914页

作者： Ulusoy, Aly-Joy Mahmoud, Herman A. Pecci, Filippo Keedwell, Edward C. Stoianov, Ivan Imperial Coll London Dept Civil & Environm Engn London SW7 2BU England Univ Exeter Exeter EX4 4QF England

This paper investigates control and design-for-control strategies to improve the resilience of sectorized water distribution networks (WDN), while minimizing pressure induced pipe stress and leakage. Both evolutionary algorithms (EA) and gradient-based mathematical optimization approaches are investigated for the solution of the resulting large-scale non-linear (NLP) and bi-objective mixed-integer non-linear programs (BOMINLP). While EAs have been successfully applied to solve discrete network design problems for large-scale WDNs, gradientbased mathematical optimization methods are more computationally efficient when dealing with large search spaces associated with continuous variables in optimal network control problems. Considering the advantages of each method, we propose a sequential hybrid method for the optimal design-for-control of large-scale WDNs, where a refinement stage relying on gradient-based mathematical optimization is used to solve continuous optimal control problems corresponding to design solutions returned by an initial EA search. The proposed method is applied to compute the Pareto front of a bi-objective design-for-control problem for the operational network BWPnet, where we consider reopening closed connections between isolated supply areas. The results show that the considered design-for-control strategy increases the resilience of BWPnet while minimizing pressure induced leakage. Moreover, the refinement stage of the proposed hybrid method efficiently improves the coarse approximation computed by the initial EA search, returning a continuous and even Pareto front approximation.

关键词： Resilience Pressure management Design-for-control Bi-objective optimization mixed-integer non-linear programming Evolutionary algorithms

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