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2015 Smart Grid Conference, SGC 2015

作者： Khorram, Seyed Abbas Tabatabaei Fard, Ali Abbaspour Tehrani Fotuhi-Firuzabad, Mahmud Safdarian, Amir Department of Electrical Engineering Center of Excellence in Power System Management and Control Sharif University of Technology Tehran Iran

ISBN: (纸本)9781509003693

Increasing redundant paths in transmission grids has always been thought to be a tool to enhance service reliability. However, network equations by intertwining power flows through redundant paths impose more limits on systems with more redundancy. Accordingly, autonomous removing of a few lines may relief capacity limit violations in some contingency events thereby enhancing service reliability. This paper aims to study impacts of manual removing of transmission lines on composite system reliability. For doing so, the existing model is extended to consider optimal transmission switching (OTS) as a remedial action. The model minimizes total damage cost imposed by load curtailments. The extended model is formulated in mixed integer linear programming (MILP) format that can be easily solved via commercial solvers. The model is applied to likely contingencies wherein violations in capacity limits are encountered. Then, the results along with occurrence probability of the contingencies are taken into use to calculate load point and system oriented reliability indices. Simulation results on the modified reliability test system (MRTS) demonstrate great enhancements in service reliability when OTS is realized. © 2015 IEEE.

关键词： Integer programming

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Introduction of dimensioned approach to evaluation of distribution transformer short circuit forces 23

Introduction of dimensioned approach to evaluation of distri...

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23rd Iranian Conference on electrical engineering, ICEE 2015

作者： Moradnouri, Ahmad Vakilian, Mehdi Elhaminia, Pedram Bahrami, Mansour Electrical Engineering Department Center of Excellence in Power System Management and Control Sharif University of Technology Tehran Iran

ISBN: (纸本)9781479919727

in this paper the radial and axial forces developed under windings short circuit conditions in two different designs of a 630 kYA distribution transformer (using analytic a^id finite element method) are determined and compared. The simulation results using FEM software verify the results of the employed analytic method. These results show that although the transformer with larger dimensions have a better operating performance and lower total owning cost with respect to one with smaller sizes (assuming the same mechanical strength for winding and support structures of both), the risk of failure due to its related short circuit forces elevates in the former. Additionally, this paper presents some analytical expressions which demonstrate the relationships between short circuit forces and transformer geometrical parameters. These relationships help transformer designers to choose the best dimensional parameters to improve the transformer performance in such a way that risk of failure of transformer due to short circuit forces doesn't increase 01 increase in a lower paste if compared with the other sample. © 2015 IEEE.

关键词： Finite element method

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Impact of erroneous measurements on power system real-time security analysis

Impact of erroneous measurements on power system real-time s...

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Iranian Conference on electrical engineering (ICEE)

作者： Mohammad Farajollahi Mahmud Fotuhi-Firuzabad Amir Safdarian Electrical Engineering Department Sharif University of Technology Center of Excellence in Power System Control and Management Tehran Iran

power system security analyses as well as decisions made to preserve system security are all on the basis of an approximate insight over the system status. This approximate insight is provided based on erroneous measurements throughout the system. The error in the input data may result in a misleading index which either increases system operating costs or jeopardizes service continuity. This paper aims at establishing an step-by-step algorithm to study impacts of error in measurements on system security indices. Two different security indices representing under voltage severity and over load severity are studied in this paper. The proposed algorithm has three major steps. In the first step, typical measurements are sampled according to the system operating state and randomly generated errors. This is done using Monte Carlo sampling approach. The second step is to extract an approximate model of the system true state which is done via state estimators. Then, security indices are calculated for both the approximated and true states in the third step. Comparison between the indices demonstrates impacts of the erroneous measurements on security assessment.

关键词： Decision support systems electrical engineering Conferences

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Robust Decentralized control of Interconnected Nonlinear systems Subject to Uncertainties and Disturbances via Generalized Extended State Observers 34

Robust Decentralized Control of Interconnected Nonlinear Sys...

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第三十四届中国控制会议

作者： ZHANG Chuanlin YANG ning HE Shuaipeng JIA Ruting Shanghai Engineering Research Center of Intelligent Management and Control for Power Process College of Automation EngineeringShanghai University of Electric Power Key Laboratory of Measurement and Control of Complex Systems of Engineering Ministry of Education Southeast University Electrical and Computer Engineering Department California State University

ISBN: (纸本)9789881563897

This paper studies the problem of robust decentralized control for a class of large-scale interconnected systems subject to uncertainties and disturbances via a generalized active disturbance rejection control method. First, a novel extended state observer(ESO) is constructed separately for each subsystem with less dependence of the precise system information and structure. Second, an explicit formula of the decentralized active disturbance rejection control(DADRC) law is presented by utilizing the output feedback domination approach. It is shown that by a delicate analysis procedure, the closed-loop system can be rendered semi-globally asymptotically stable only using decentralized output feedback anti-disturbance controller. Numerical simulations show the efficiency of the proposed method.

关键词： output feedback control global stabilization disturbance rejection control extended state observer

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Optimal Placement of the Distribution Substations to Improve Reliability Under Load Growth

Optimal Placement of the Distribution Substations to Improve...

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IEEE power and Energy Society General Meeting

作者： M. R. Haghifam M. Esmaeeli A. Kazemi H. Shayanfar Faculty of Electrical and Computer Engineering Tarbiat Modares University Center of Excellence for Power Systems Control and Operation Department of Electrical Engineering Iran University of Science and Technology

ISBN: (纸本)9781467380416

In this paper, an approach is proposed for planning distribution networks in which the placement of distribution transformer is optimally planned. The size, number, and placement of distribution transformers are optimally determined in order to improve system reliability and to minimize the losses under load growth. An objective function is constituted, composed of the investment cost, maintenance cost, loss cost, and reliability cost. The reliability worth is not usually considered in the optimization of the distribution substation placement. However, it may be effective on the planning problem. The proposed approach is applied to a test system consisting of 42 electric load points. It is observed that the considering reliability in the planning approach reduces the total cost of the distribution transformer placement. However, the associated investment cost is increased but the reliability cost is more decreased.

关键词： Distribution Planning Load Growth Mixed Integer Nonlinear Programming (MINLP) Reliability Transformer

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A heuristic ranking approach on capacity benefit margin determination using pareto-based evolutionary programming technique

Scientific World Journal

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Scientific World Journal 2015年第1期2015卷 731013页

作者： Othman, Muhammad Murtadha Abd Rahman, Nurulazmi Musirin, Ismail Fotuhi-Firuzabad, Mahmud Rajabi-Ghahnavieh, Abbas Committee of Research (CORE) Advanced Computing and Communication (ACC) Universiti Teknologi MARA Shah Alam Selangor 40450 Malaysia Faculty of Electrical Engineering Universiti Teknologi MARA Shah Alam Selangor 40450 Malaysia Engineering Centre University Malaysia Perlis Kampus Kubang Gajah Arau Perlis 02600 Malaysia Centre of Excellence in Power System Management and Control Electrical Engineering Department Sharif University of Technology Tehran 11365-11155 Iran Department of Energy Engineering Sharif University of Technology Tehrana 11365-11155 Iran

This paper introduces a novel multiobjective approach for capacity benefit margin (CBM) assessment taking into account tie-line reliability of interconnected systems. CBM is the imperative information utilized as a reference by the load-serving entities (LSE) to estimate a certain margin of transfer capability so that a reliable access to generation through interconnected system could be attained. A new Pareto-based evolutionary programming (EP) technique is used to perform a simultaneous determination of CBM for all areas of the interconnected system. The selection of CBM at the Pareto optimal front is proposed to be performed by referring to a heuristic ranking index that takes into account system loss of load expectation (LOLE) in various conditions. Eventually, the power transfer based available transfer capability (ATC) is determined by considering the firm and nonfirm transfers of CBM. A comprehensive set of numerical studies are conducted on the modified IEEE-RTS79 and the performance of the proposed method is numerically investigated in detail. The main advantage of the proposed technique is in terms of flexibility offered to an independent system operator in selecting an appropriate solution of CBM simultaneously for all areas. © 2015 Muhammad Murtadha Othman et al.

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A practical application of the Delphi method in maintenance-targeted resource allocation of distribution utilities

A practical application of the Delphi method in maintenance-...

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International Conference on Probabilistic Methods Applied to power systems (PMAPS)

作者： Payman Dehghanian Moein Moeini-Aghtaie Mahmud Fotuhi-Firuzabad Roy Billinton Sharif University of Technology Tehran Tehran IR Center of Excellence in Electrical Power System Management and Control Sharif University of Technology Tehran Iran Department of Electrical Engineering University of Saskatchewan Saskatoon Saskatchewan Canada

Trying to find the most efficient and cost-effective decisions on the maintenance of different component types in power distribution systems is an increasingly challenging concern largely driven by the current financial constraints in distribution utilities worldwide. In regard to deal with this challenge, the paper presents a practical application of the Delphi method and the Modified Analytical Hierarchical Process (MAHP) that can be used to find the most critical component types of the system in order to assist in accordingly allocating the available maintenance budget. The proposed approach involves the experience and knowledge held by experts and the historical empirical performance data in the utility data management systems to create the associated decisions. The approach has been applied in the Alborz Distribution system in Tehran, Iran. The results obtained and the lessons learned are reported in detail.

关键词： Maintenance engineering Decision making Resource management power distribution power cables Reliability Planning

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U-shaped energy loss curves utilization for distributed generation optimization in distribution networks

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Journal of Zhejiang University-Science C(Computers and Electronics) 2013年第11期14卷 887-898页

作者： Reza EBRAHIMI Mehdi EHSAN Hassan NOURI Department of Electrical Engineering Science and Research BranchIslamic Azad University Centre of Excellence in Power System Management and Control (CEPSMC) Sharif University of Technology Department of Engineering Design and Mathematics University of the West of England (UWE Bristol)

We propose novel techniques to find the optimal location,size,and power factor of distributed generation(DG) to achieve the maximum loss reduction for distribution *** the optimal DG location and size is achieved simultaneously using the energy loss curves technique for a pre-selected power factor that gives the best DG *** on the network's total load demand,four DG sizes are *** are used to form energy loss curves for each bus and then for determining the optimal DG *** study shows that by defining the energy loss minimization as the objective function,the time-varying load demand significantly affects the sizing of DG resources in distribution networks,whereas consideration of power loss as the objective function leads to inconsistent interpretation of loss reduction and other *** devised technique was tested on two test distribution systems of varying size and complexity and validated by comparison with the exhaustive iterative method(EIM) and recently published *** showed that the proposed technique can provide an optimal solution with less computation.

关键词： Distributed generation(DG) Distribution networks Loss reduction DG optimization Energy loss curves

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A decentralized self-adjusting control strategy for reactive power management in an islanded multi-bus MV microgrid

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Canadian Journal of electrical and Computer engineering 2013年第1期36卷 18-25页

作者： Hamzeh, Mohsen Mokhtari, Hossein Karimi, Houshang Center of Excellence in Power System Management and Control Sharif University of Technology Tehran 11365-9363 Iran Department of Electrical Engineering École Polytechnique de Montréal QC H3C 3A7 Canada

This paper presents a decentralized self-adjusting reactive power controller for the autonomous operation of a multi-bus medium voltage (MV) microgrid. The main objective of the proposed control strategy of each distributed generation (DG) unit is to compensate the reactive power of its local loads and to share the reactive power of the nonlocal loads among itself and other DG units. The proposed control strategy includes an improved droop controller whose parameters are adjusted according to the reactive power of the local loads. A virtual inductive impedance loop is augmented to the voltage controller to enhance the steady state and transient responses of the proposed reactive power management scheme. The small signal analysis of the proposed method is presented to ensure stability of the system for different reactive power values. The presented strategy considerably enhances the voltage profiles of the microgrid buses as compared with the conventional droop methods. The proposed method does not require any communication link and minimizes the reactive power flow in the MV lines, thus reducing the losses of the overall microgrid. The performance of the proposed control scheme is verified by using digital time-domain simulation studies in the PSCAD/EMTDC software environment. © 2013 IEEE.

关键词： controllers

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Research on operational characteristics and allocation of rotary power flow controller

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Iranian Journal of electrical and Computer engineering 2013年第1-2期12卷 41-48页

作者： Tolue Khayami, M. Shayanfar, H.A. Kazemi, A. Department of Electrical Engineering Science and Research Branch Islamic Azad University Tehran Iran Center of Excellence for Power System Automation and Operation Department of Electrical Engineering Iran University of Science and Technology Tehran Iran

FACTS devices increase the capacity, flexibility and controllability of the transmission networks. Utilizing high power semiconductor switches for implementing these devices raise their cost. On the other hand, the disturbances caused by the switching process may lead to power quality problems. Rotary power Flow controller (RPFC) is one of the FACTS devices based on Rotary Phase Shifting Transformer (RPST) configuration. In this paper, using a novel formulation, steady state operational specification of this device is analyzed considering detailed model of the device components such as magnetizing inductances. The device ability to control active and reactive power of the transmission lines is studied. The equations for calculating the operational limits are presented. Based on calculated operational margins, RPEC allocation according to loading and voltage security indices in north-east of Iran network is presented. © 2013 ACECR.

关键词： Flexible AC transmission systems

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