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Computationally efficient adaptive algorithm for resource allocation in orthogonal frequency-division multiple-access-based cognitive radio networks

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IET COMMUNICATIONS 2015年第12期9卷 1442-1449页

作者： Raeis, Mahdi Shahtalebi, Kamal Forouzan, Amir Reza Univ Isfahan Dept Elect Engn Esfahan *** Iran

In this study, the authors examine resource allocation in an orthogonal frequency-division multiple-access-based cognitive radio (CR) network which dynamically senses primary users (PUs) spectrum and opportunistically uses available channels. The aim is resource allocation such that the CR network throughput is maximised under the PUs maximum interference constraint and cognitive users (CUs) transmission power budget. This problem is formulated as a mixed-integer non-linear programming problem which is MATHEMATICAL SCRIPT CAPITAL NP-hard in general and infeasible to solve in real-time. To reduce the computational complexity, the authors decouple the problem into two separate steps. After initial power allocation, in the first step, an adaptive algorithm is employed to assign subcarriers to the CUs toward throughput maximisation by using these initial powers. In the second step, power is allocated optimally to the assigned subcarriers. Simulation results show that the proposed method nearly achieves the optimal solution in a small number of iterations meaning significant reduction in the computational complexity.

关键词： computational complexity cognitive radio OFDM modulation frequency division multiple access channel allocation wireless channels radiofrequency interference nonlinear programming integer programming iterative methods resource allocation computationally efficient adaptive algorithm resource allocation orthogonal frequency division multiple access cognitive radio network CR network throughput maximization primary user spectrum radio channel PU maximum interference constraint cognitive users CU transmission power budget mixed integer nonlinear programming problem NP-hard problem computational complexity reduction power allocation iteration method

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Active distribution network expansion planning integrating dispersed energy storage systems

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IET GENERATION TRANSMISSION & DISTRIBUTION 2016年第3期10卷 638-644页

作者： Xing, Haijun Cheng, Haozhong Zhang, Yi Zeng, Pingliang Shanghai Jiao Tong Univ Dept Elect Engn Shanghai 200240 Peoples R China State Grid Fujian Elect Power Res Inst Fuzhou 350007 Fujian Province Peoples R China China Elect Power Res Inst Beijing 100085 Peoples R China

This study proposes the convex model for active distribution network expansion planning integrating dispersed energy storage systems (DESS). Four active management schemes, distributed generation (DG) curtailment, demand side management, on-load tap changer tap adjustment and reactive power compensation are considered. The optimisation of DESS for peak shaving and operation cost decreasing is also integrated. The expansion model allows alternatives to be considered for new wiring, new substation, substation expansion and DG installation. The distribution network expansion planning (DNEP) problem is a mixed integer non-linear programming problem. Active management and uncertainties especially with the DG integration make the DNEP problem much complex. To find the suitable algorithm, this study converts the DNEP problem to a second-order cone programming model through distflow equations and constraints relaxation. A modified 50-bus application example is used to verify the proposed model.

关键词： relaxation theory integer programming convex programming reactive power on load tap changers power system management demand side management energy storage power generation planning distributed power generation power distribution planning active distribution network expansion planning dispersed energy storage system convex model DESS active management scheme distributed generation curtailment generation curtailment demand side management on-load tap changer tap adjustment reactive power compensation peak shaving operation cost decrement DG installation substation expansion DNEP problem mixed integer nonlinear programming problem second-order cone programming model distflow equation constraint relaxation

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Reactive power dispatch and planning using a non-linear branch-and-bound algorithm

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IET GENERATION TRANSMISSION & DISTRIBUTION 2010年第8期4卷 963-973页

作者： Estevam, C. R. N. Rider, M. J. Amorim, E. Mantovani, J. R. S. UNESP Univ Estadual Paulista Fac Engn Ilha Solteira Dept Engn Elet Ilha Solteira SP Brazil Univ Fed Mato Grasso Sul UFMS Dept Engn Elet Campo Grande MS Brazil

This study proposes the use of a non-linear branch-and-bound (B&B) algorithm to solve the reactive power dispatch and planning problem of an electrical power system. The problem is formulated as a mixed integer non-linear programming (MINLP) problem. The MINLP is relaxed resulting in a set of non-linear programming (NLP) problems, which are solved at each node of the B&B tree through a primal dual-interior point algorithm. The non-linear B&B algorithm proposed has special fathoming criteria to deal with non-linear and multimodal optimisation models. The fathoming tests are redefined, adding a safety margin value to the objective function of each NLP problem before they are fathomed through the objective function criteria, avoiding convergence to local optimum solutions. The results are presented using three test systems from the specialised literature. The B&B algorithm found several optimum local solutions and the best solution was found after solving some NLP problems, with little computational effort.

关键词： Power system planning and layout load dispatching Optimisation techniques nonlinear programming objective function criteria safety margin value tree searching integer programming reactive power dispatch multimodal optimisation models nonlinear branch-and-bound algorithm reactive power mixed integer nonlinear programming problem electrical power system planning problem fathoming criteria convergence nonlinear optimisation models Combinatorial mathematics power system planning primal dual-interior point algorithm

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Toward coordinated look-ahead reactive power optimisation for distribution networks with minimal control

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IET GENERATION TRANSMISSION & DISTRIBUTION 2018年第11期12卷 2707-2717页

作者： Ding, Min Chiang, Hsiao-Dong Li, Peng Tianjin Univ Sch Elect & Informat Engn Tianjin Peoples R China Cornell Univ Sch ECE Ithaca NY USA China Southern Grid Co Elect Power Res Inst Guangzhou Guangdong Peoples R China

A coordinated look-ahead reactive power optimisation method is proposed to minimise the required number of operating control devices for a time horizon of 24h. The aim is to determine, via solving a mixed integer non-linear programming (MINLP) problem, optimum value settings of transformer taps, capacitor banks and reactive power output of distributed generators (DGs) based on the day-ahead load demand and active power output of DGs satisfying the engineering and operational constraints. The proposed method employs a three-stage method: assessment stage, time-period-partitioning stage, and coordinated reactive power optimisation stage. The first stage assesses the hourly voltage profile and available delivery capability margin of the system, while the time-period-partitioning stage uses clustering algorithm based on power-flow solution to partition time periods into coherent time durations. The MINLP problem is solved in the proposed coordinated optimisation stage. A modified IEEE13 case and IEEE123 case are used to verify the effectiveness of the proposed three-stage method.

关键词： power distribution control reactive power control integer programming nonlinear programming minimisation power transformers power capacitors distributed power generation pattern clustering load flow power generation control distribution network coordinated look-ahead reactive power optimisation method mixed integer nonlinear programming problem MINLP problem transformer tap capacitor bank reactive power output distributed generator DG day-ahead load demand active power output assessment stage method time-period-partitioning stage method coordinated reactive power optimisation stage method time-period-partitioning stage clustering algorithm power-flow solution modified IEEE13 case study IEEE123 case study time 24 h

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Integral methodology for distribution systems reconfiguration based on optimal power flow using Benders decomposition technique

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IET GENERATION TRANSMISSION & DISTRIBUTION 2009年第6期3卷 521-534页

作者： Khodr, H. M. Martinez-Crespo, J. GECAD Polytech Inst Porto ISEP IPP P-4200072 Oporto Portugal Univ Carlos III Madrid Dept Elect Madrid 28911 Spain

A new and efficient methodology for distribution network reconfiguration integrated with optimal power flow (OPF) based on a Benders decomposition approach is presented. The objective minimises power losses, balancing load among feeders and subject to constraints such as capacity limit of branches, minimum and maximum power limits of substations or distributed generators, minimum deviation of bus voltages and radial optimal operation of networks. A variant of the generalised Benders decomposition algorithm is applied to solve the problem. The formulation can be embedded under two stages;the first one is the master problem and is formulated as a mixed integer non-linear programming problem. This stage determines the radial topology of the distribution network. The second stage is the slave problem and is formulated as a non-linear programming problem. This stage is used to determine the feasibility of the master problem solution by means of an OPF and provides information to formulate the linear Benders cuts that connect both problems. The model is programmed in GAMS mathematical modelling language. The effectiveness of the proposal is demonstrated through two examples extracted from the specialised literature.

关键词： GAMS mathematical modeling language distribution network reconfiguration distribution networks integer programming Distribution networks load flow optimal power flow Benders decomposition technique mixed integer nonlinear programming problem Optimisation techniques nonlinear programming

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Synthesis of Complex Thermally Coupled Distillation Systems Including Divided Wall Columns

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AICHE JOURNAL 2013年第4期59卷 1139-1159页

作者： Caballero, Jose A. Grossmann, Ignacio E. Univ Alicante Dept Chem Engn E-03080 Alicante Spain Carnegie Mellon Univ Dept Chem Engn Pittsburgh PA 15213 USA

The design of thermally coupled distillation sequences explicitly including the possibility of divided wall columns (DWC) is described. A DWC with a single wall can be considered thermodynamically equivalent to a fully thermally coupled (FTC) subsystem formed by three separation tasks (a Petlyuk configuration in the case of three-component mixtures). It is shown how to systematically identify all the sequences of separation tasks that can produce configurations that include at least a DWC. Feasible sequences that explicitly include DWCs are enforced through a set of logical relationships in terms of Boolean variables. These logical relationships include as feasible alternatives from conventional columns (each column must have a condenser and a reboiler) to FTC systems (only one reboiler and one condenser in the entire system). A comprehensive disjunctive programming formulation for finding the optimal solution is presented. The model is based on the Fenske, Underwood Gilliland equations. However, the disjunctive formulation allows easily the use of any other shortcut, aggregated or even rigorous model without modifying much the structure of the model. Two illustrative examples illustrate the procedure. (C) 2012 American Institute of Chemical Engineers AIChE J, 59: 1139-1159, 2013

关键词： distillation thermally coupled distillation mixed integer nonlinear programming problem divided wall column superstructure optimization disjunctive programming problem

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Congestion management through rotor stress controlled optimal transmission switching

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IET GENERATION TRANSMISSION & DISTRIBUTION 2015年第12期9卷 1369-1376页

作者： Nasrolahpour, Ehsan Ghasemi, Hassan Univ Tehran Sch Elect & Comp Engn Tehran Iran

Security constrained optimal transmission switching (SC-OTS) can be an essential part of future smart grids with flexible topologies. Transmission switching, however, can have adverse impact on generators because of creating excessive torque on their rotor shafts. In this study, SC-OTS as an effective tool is applied to relieve congestion while considering AC constraints and generator rotor shaft impact caused by switching. As opposed to previously used simplified models based on standing phase angle, this study utilises dynamic response of generators to accurately calculate the actual stresses on rotors because of switching. In addition, network N-1 security criterion is taken into account. In the proposed model, OTS actions are obtained through a bi-level process. In the upper level, OTS set is determined and the applicability of each action is checked in the lower level. The proposed methodology leads to a mixed integer non-linear programming problem, which is formulated and solved based on Benders decomposition. Test results for the IEEE 57 and 118-bus systems illustrate the effectiveness of the method in removing congestion while ensuring that destructive switching manoeuvres are avoided.

关键词： power system security smart power grids rotors dynamic response integer programming nonlinear programming IEEE standards power system management power transmission congestion management rotor stress controlled optimal transmission switching security constrained optimal transmission switching SC-OTS smart grids flexible topologies rotor shafts AC constraints generator rotor shaft impact simplified models standing phase angle dynamic response network N-1 security criterion bilevel process mixed integer nonlinear programming problem IEEE 57-bus systems IEEE 118-bus systems destructive switching manoeuvres benders decomposition

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SCUC-based optimal power tracing approach for scheduling physical bilateral transactions and its verification via an integrated power-money flow analysis

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IET GENERATION TRANSMISSION & DISTRIBUTION 2016年第10期10卷 2399-2409页

作者： Zhu, Songming Wu, Lei Guan, Xiaohong Wu, Jiang Clarkson Univ ECE Dept Potsdam NY 13699 USA Xi An Jiao Tong Univ Moe Klinns Lab Xian 410069 Shaanxi Peoples R China

This study discusses a security-constrained unit commitment (SCUC) based optimal power tracing approach, which adopts the proportional power tracing method to trace power flows of the network for simultaneously satisfying physical contract paths and financial contract quantities of bilateral transactions. Thus, optimal solutions of the proposed model, including unit commitment and generation dispatch of generators and angle statuses of phase shifters, would simultaneously meet physical and financial requirements of bilateral transactions, and in turn reduce the impacts of loop flows induced by bilateral transactions to third parties of the networked system. The proposed model is a mixed integer non-linear programming problem because of the non-linear proportional power tracing constraints, and the revised outer approximation algorithm is discussed to effectively solve the problem. The effectiveness of the proposed model is further evaluated via an integrated power-money flow analysis, based on the locational marginal price based energy payments and the min-max fairness policy based transmission usage charges. Numerical case studies show that the proposed model, as compared with traditional financial bilateral transaction models, presents potential advantages to avoid loop flows and reduce the impacts to third parties in terms of energy and transmission usage payments.

关键词： power generation dispatch power generation scheduling power system security load flow phase shifters power transmission economics power generation economics integer programming nonlinear programming approximation theory minimax techniques SCUC-based optimal power tracing approach physical bilateral transaction scheduling integrated power-money flow analysis security-constrained unit commitment based optimal power tracing approach bilateral transaction financial contract quantity generators generation dispatch phase shifter loop flow impact reduction mixed integer nonlinear programming problem nonlinear proportional power tracing constraint revised outer approximation algorithm locational marginal price based energy payment min-max fairness policy based transmission usage charge transmission usage payment energy usage payment

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Robust probabilistic optimal voltage sag monitoring in presence of uncertainties

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IET GENERATION TRANSMISSION & DISTRIBUTION 2016年第16期10卷 4240-4248页

作者： Nasiri, Saeed Seifi, Hossein Tarbiat Modares Univ Dept Elect Engn Tehran Iran

This study presents an optimisation model to achieve an optimal voltage sag monitoring programme. To cover the main uncertainty associated with fault impedance, a novel approach termed as probabilistic monitor reach area (PMRA) is developed. Moreover, PMRA is employed to consider reliability of the monitoring equipment impact. Additionally, several indices based on PMRA are defined to distinguish the optimal programme when outage of generators, loading level, line outage and feeder reconfiguration may result in several programmes. Besides, the other advantage of the proposed method is aptitude of modelling large load switching as an influential source of voltage sags. The model determines the number and the location of monitors in such a way that a pre-defined probability of observability is satisfied. Capability of the proposed methodology is checked for several test systems and illustrated here on the 24-bus reliability test system and on the 34-node test feeder. Numerical results and their comparison with the commonly used MRA method reveal that the proposed optimal voltage sag monitoring programme is robust against uncertainties including fault impedance, load variations and outage of the generators/lines.

关键词： power supply quality integer programming nonlinear programming electric impedance observability power system measurement power system reliability linearisation techniques load (electric) probability power system faults uncertain systems robust probabilistic optimal voltage sag monitoring optimisation model fault impedance probabilistic monitor reach area PMRA monitoring equipment impact reliability generator outage loading level line outage feeder reconfiguration large load switching modelling observability mixed integer nonlinear programming problem linearisation technique 24-bus reliability test system 34-node test feeder uncertainty robustness load variations

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Cluster oriented resource allocation and power optimisation for D2D network in cellular communications

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IET NETWORKS 2020年第4期9卷 170-179页

作者： Gour, Radhika Tyagi, Anshul Indian Inst Technol Roorkee Elect & Commun Engn Roorkee 247667 Uttarakhand India

This work proposes a cluster oriented channel assignment and difference of two convex functions (d.c.) programming based power optimisation algorithm for the downlink device-to-device (D2D) communication underlaying cellular networks. The authors' objective is to maximise D2D throughput while protecting the performance of existing cellular users (CUs) whose channel is reused among multiple D2D pairs, by imposing a minimum rate requirement constraint on each CU. The joint channel and power optimisation problem is a mixed integer non-linear programming problem that is NP-hard to solve. Therefore, a three stage solution is proposed: cluster formation to minimise the interference among the D2D pairs followed by an optimal channel assignment using the Hungarian algorithm and then an iterative power optimisation algorithm based on d.c. programming. Moreover, the transmission power of base station and D2D users is optimised on the same channel while considering the mutual interference among D2D pairs. Numerical results verify the effectiveness of the proposed resource allocation scheme in terms of the D2D sum rate and the number of successful transmission of D2D users. Moreover, the iterative power optimisation algorithm shows a fast convergence behaviour. In addition to this, the energy efficiency is also analysed with respect to various parameters.

关键词： nonlinear programming cellular radio integer programming resource allocation channel allocation convex programming iterative methods multiple D2D pairs minimum rate requirement constraint power optimisation problem mixed integer nonlinear programming problem cluster formation optimal channel assignment Hungarian algorithm iterative power optimisation algorithm transmission power base station cellular transmission resource allocation scheme D2D sum rate D2D maximum transmit power cellular communications cluster oriented channel assignment downlink device-to-device communication cellular networks cellular users difference of two convex functions dc programming based power optimisation algorithm

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