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Total 205 records

    Power quality standards and their application to a granite factory

    , Article 2006 International Conference on Power Electronics, Drives and Energy Systems, PEDES '06, New Delhi, 12 December 2006 through 15 December 2006 ; 2006 ; 078039772X (ISBN); 9780780397729 (ISBN) Hasani, S ; Donyavi, F ; Masoudi, M ; Mokhtari, H ; Sharif University of Technology
    2006
    Abstract
    This paper presents the results of a thorough analysis of applying power quality standards to a granite factory. It explains the procedure of determining power quality indices in a power system. The paper presents the field data and provides the results of statistical analysis in order to extract power quality indices. A comparison against standard limits is also given. The case study gives an overview of power quality in such customers and brings up some practical limitations when applying power quality standards. ©2006 IEEE  

    A competitive market structure for reactive power procurement

    , Article Iranian Journal of Science and Technology, Transaction B: Engineering ; Volume 30, Issue 2 , 2006 , Pages 259-276 ; 03601307 (ISSN) Mozafari, B ; Ranjbar, A. M ; Amraee, T ; Shirani, A. R ; Sharif University of Technology
    2006
    Abstract
    This paper first proposes a competitive market structure for reactive power procurement and then develops a methodology for incorporating voltage stability problems into the model. The owners of electric transactions should participate in this competitive framework and submit their own firmness bids in ($/MW) to the Independent/System/Market Operator (ISOIMO). ISO clears the market for reactive energy regarding the value of each transaction and utilization cost of reactive power on one hand, and the impact of transaction amount on the voltage security of the power system on the other hand. Here, the voltage stability margin is incorporated into the power flow equations so that the security... 

    Mathematical methods of combining deterministic/probabilistic criteria in short-term generating reserve scheduling

    , Article Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering ; Volume 218, Issue 2 , 2004 , Pages 69-75 ; 09544089 (ISSN) Billinton, R ; Fotuhi Firuzabad, M ; Sharif University of Technology
    Professional Engineering Publishing  2004
    Abstract
    Probabilistic approaches generally base the design and operating constraints on the criterion that the risk of certain events must not exceed preselected limits. Many utilities still prefer to use deterministic techniques owing to the difficulty in interpreting a numerical risk index and the lack of sufficient information provided by a single index. This is especially true in the power system operating domain as existing probabilistic risk indices do not provide any assessment of the capacity reserve available during the course of system operation. A practical way to overcome these difficulties is to embed deterministic considerations into the probabilistic framework in the form of system... 

    Identification of critical generating units for maintenance: A game theory approach

    , Article IET Generation, Transmission and Distribution ; Volume 10, Issue 12 , 2016 , Pages 2942-2952 ; 17518687 (ISSN) Pourahmadi, F ; Fotuhi Firuzabad, M ; Dehghanian, P ; Sharif University of Technology
    Institution of Engineering and Technology 
    Abstract
    With the rapid evolution of electricity markets and the need for higher economic efficiency of power industry, attempts for lowering down the maintenance costs as a large portion of system operation expenses seem imperative. Recognised as a crucial step in practical implementation of modern maintenance paradigms, e.g. reliability-centred maintenance, this study proposes an efficient method to quantify the generating units' criticality on the bulk power system reliability performance. The proposed approach utilises a solution concept of game theory and evaluates the contribution of each generating unit on the overall system reliability when a higher-order contingency occurs. The suggested... 

    Application of edge theorem for robust stability analysis of a power system with participating wind power plants in automatic generation control task

    , Article IET Renewable Power Generation ; Volume 11, Issue 7 , 2017 , Pages 1049-1057 ; 17521416 (ISSN) Toulabi, M ; Bahrami, S ; Ranjbar, A. M ; Sharif University of Technology
    Institution of Engineering and Technology  2017
    Abstract
    This study investigates the dynamic participation of wind power plants (WPPs) in the automatic generation control (AGC) task. The pre-specified model of wind farm in the AGC studies has been used. It is shown that operating of WPPs at the command mode results in a significant improvement in the frequency behaviour of power system due to their faster response. However, the WPPs may change their operation mode from the command mode to the maximum power point mode according to the wind speed conditions and load variations. This reduces the improvement in the frequency response. In this condition, the shortage in the wind power should be compensated by the conventional units. Thus, the share of... 

    Standard test systems for modern power system analysis: an overview

    , Article IEEE Industrial Electronics Magazine ; Volume 13, Issue 4 , 2019 , Pages 86-105 ; 19324529 (ISSN) Peyghami, S ; Davari, P ; Fotuhi Firuzabad, M ; Blaabjerg, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    The reliable design, planning, and operation of power systems are of paramount importance for providing reliable services to customers. This article reviews the different aspects of power system reliability, ranging from planning to operation. Standard benchmarks employed for power system studies are reviewed according to nearly 2,500 IEEE journal papers from 1986 to early 2019. Our overview provides the pros and cons of existing test systems, implying the lack of appropriate benchmarks for future power system studies, including renewable resources and modern technologies. Furthermore, this article presents requirements for updating and modifying the benchmarks for modern power systems... 

    Optimal placement of protective and controlling devices in electric power distribution systems: a MIP model

    , Article IEEE Access ; Volume 7 , 2019 , Pages 122827-122837 ; 21693536 (ISSN) Izadi, M ; Safdarian, A ; Moeini Aghtaie, M ; Lehtonen, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    This paper presents a mathematical model for simultaneous deployment of protective devices (PDs) and controlling devices (CDs) in distribution networks. The PDs include fuses and reclosers and the CDs are remote controlled switches (RCSs) and manual switches (MSs). The model is to minimize equipment costs as well as sustained and momentary interruption costs. It considers the coordination of fuses and reclosers during temporary faults involving fuse saving and fuse blowing schemes. The model is in mixed integer programming (MIP) fashion which can be effectively solved with available solvers. The performance of the proposed model is verified through applying it to Bus 4 of Roy Billinton test... 

    Optimal placement of protective and controlling devices in electric power distribution systems: A MIP Model

    , Article IEEE Access ; Volume 7 , 2019 , Pages 122827-122837 ; 21693536 (ISSN) Izadi, M ; Safdarian, A ; Moeini Aghtaie, M ; Lehtonen, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    This paper presents a mathematical model for simultaneous deployment of protective devices (PDs) and controlling devices (CDs) in distribution networks. The PDs include fuses and reclosers and the CDs are remote controlled switches (RCSs) and manual switches (MSs). The model is to minimize equipment costs as well as sustained and momentary interruption costs. It considers the coordination of fuses and reclosers during temporary faults involving fuse saving and fuse blowing schemes. The model is in mixed integer programming (MIP) fashion which can be effectively solved with available solvers. The performance of the proposed model is verified through applying it to Bus 4 of Roy Billinton test... 

    Method of combined static and dynamic analysis of voltage collapse in voltage stability assessment

    , Article 2005 IEEE/PES Transmission and DistributionConference and Exhibition - Asia and Pacific, Dalian, 15 August 2005 through 18 August 2005 ; Volume 2005 , 2005 , Pages 1-6 ; 0780391144 (ISBN); 9780780391147 (ISBN) Hasani, M ; Parniani, M ; Sharif University of Technology
    2005
    Abstract
    Different analysis methods have been used for voltage stability assessment. In comparison with static analysis methods, little work has been done on dynamic analysis of large interconnected power systems. Voltage instability can be studied effectively with a combination of static approaches and time simulations. This paper discusses voltage stability assessment using mixed static and dynamic techniques. Using static methods, a voltage stability based ranking is carried out to specify faint buses, generators and links in power system. The system is analyzed for most severe conditions. Then, time domain simulation is performed for the conditions determined by voltage instability ranking. The... 

    Reliability evaluation of deregulated electric power systems for planning applications

    , Article Reliability Engineering and System Safety ; Volume 93, Issue 10 , 2008 , Pages 1473-1484 ; 09518320 (ISSN) Ehsani, A ; Ranjbar, A. M ; Jafari, A ; Fotuhi Firuzabad, M ; Sharif University of Technology
    2008
    Abstract
    In a deregulated electric power utility industry in which a competitive electricity market can influence system reliability, market risks cannot be ignored. This paper (1) proposes an analytical probabilistic model for reliability evaluation of competitive electricity markets and (2) develops a methodology for incorporating the market reliability problem into HLII reliability studies. A Markov state space diagram is employed to evaluate the market reliability. Since the market is a continuously operated system, the concept of absorbing states is applied to it in order to evaluate the reliability. The market states are identified by using market performance indices and the transition rates... 

    Reliability evaluation of deregulated power system considering competitive electricity market

    , Article Iranian Journal of Science and Technology, Transaction B: Engineering ; Volume 31, Issue 6 , December , 2007 , Pages 603-616 ; 10286284 (ISSN) Ehsani, A ; Ranjbar, A. M ; Jafari, A ; Fotuhi Firuzabad, M ; Sharif University of Technology
    2007
    Abstract
    In a deregulated electric power system in which a competitive electricity market can influence system reliability, system analysts are rapidly recognizing that they cannot ignore market risks. This paper first proposes an analytical probabilistic model for the reliable evaluation of competitive electricity markets and then develops a methodology for incorporating the market reliability problem into composite power system reliability studies. The market reliability is evaluated using the Markov state space diagram. Since the market is a continuously operated system, the concept of absorbing states is applied to it in order to evaluate reliability. The market states are identified using market... 

    A novel straightforward unit commitment method for large-scale power systems

    , Article IEEE Transactions on Power Systems ; Volume 22, Issue 4 , 2007 , Pages 2134-2143 ; 08858950 (ISSN) Hosseini, S. H ; Khodaei, A ; Aminifar, F ; Sharif University of Technology
    2007
    Abstract
    In this paper, a novel fast straightforward method for thermal generating units scheduling is presented. The new method decomposes the solution of the unit commitment (UC) problem into three subproblems. In the first subproblem, the quadratic cost functions of units are linearized and hourly optimum solution of UC is obtained considering all constraints except the minimum up/down time constraints. In the second subproblem, the minimum up/down times are enforced through a novel optimization process by modifying the schedule obtained in the first step. Finally, in the third subproblem, the extra reserve is minimized using a new decommitment algorithm. For testing the proposed method, the... 

    Multi-port frequency-dependent network equivalent for electromagnetic transient studies

    , Article 37th Annual North American Power Symposium, 2005, Ames, IA, 23 October 2005 through 25 October 2005 ; Volume 2005 , 2005 , Pages 287-295 ; 0780392558 (ISBN); 9780780392557 (ISBN) Porkar, B ; Vakilian, M ; Feuillet, R ; Ghassemi, M ; Akhavan, A ; Sharif University of Technology
    2005
    Abstract
    Network equivalents can be used to represent parts of a power system to reduce the complexity and the computation time during the simulation of electromagnetic transients. The goal is to simplify the representation while preserving the accuracy of transients in the remainder. In this work a method is developed for construction of single and multi-port Frequency Dependent Network Equivalent (FNDE). In this equivalent model the input admittance matrix is approximated by a rational function in the frequency domain. This method is developed for both single and multi phase systems. Several examples showing the accuracy and efficiency of the developed FDNE is presented  

    Composite system reliability evaluation incorporating protection system failures

    , Article Canadian Conference on Electrical and Computer Engineering 2005, Saskatoon, SK, 1 May 2005 through 4 May 2005 ; Volume 2005 , 2005 , Pages 486-489 ; 08407789 (ISSN) Bozchalui, M. C ; Sanaye Pasand, M ; Fotuhi Firuzabad, M ; Sharif University of Technology
    2005
    Abstract
    Protection system malfunction play a significant role in the sequence of events leading to power system blackouts. This paper describes power system reliability evaluation incorporating protection system failures. A reliability model is used in order to determine the impact of protection system failure on power system reliability. The mechanism and scheme of protection and their hidden failure are analyzed based on their contribution to the cascading outage after occurrence of a fault. A number of reliability indices such as LOLP, EENS and ECI are calculated to describe the impact of protection system failures on reliability of power system. © 2005 IEEE  

    Harmonic filter design consideration for a Tire-Rubber factory

    , Article 5th IASTED International Conference on Power and Energy Systems, EuroPES 2005, Benalmadena, 15 June 2005 through 17 June 2005 ; 2005 , Pages 380-383 ; 14827891 (ISSN) Zebardast, A ; Mokhtari, H ; Hamza M. H ; IASTED ; Sharif University of Technology
    2005
    Abstract
    Increase in the number of non-linear loads has increased harmonic pollution in industries, resulting in lower power factor and more losses. Harmonics may also lead to adverse conditions in cases they match a resonance frequency existing in the system. To alleviate the problems of harmonics, tuned harmonic filters are used. However, design and installation of passive elements in power systems or industries requires special attentions due to the possible resonances that may occur. In this paper, a Tire-Rubber company is analyzed for a filter installation. Harmonic analysis is performed, and site measurements are examined. Cautions to be taken for design consideration are then discussed  

    Grid modernization for enhancing the resilience, reliability, economics, sustainability, and security of electricity grid in an uncertain environment

    , Article Scientia Iranica ; Volume 23, Issue 6 , 2016 , Pages 2862-2873 ; 10263098 (ISSN) Shahidehpour, M ; Fotuhi Friuzabad, M ; Sharif University of Technology
    Sharif University of Technology  2016
    Abstract
    This paper reviews the merits of modernizing the power grid and discusses the way electric utilities in various countries are directing their practices toward offering enhanced sustainability, reliability, resilience, security, and economics to their respective consumers. The modernization of the electricity grid, which has evolved as the brainchild of electricity restructuring, has been made all the more urgent by the virtually pervasive dependence of modern lives on a reliable, clean, and secure supply of affordable electricity. The electric utility industry restructuring, which has staged many institutional, regulatory, and business models, has enabled the modern electricity grid to take... 

    Steady-state analysis and performance of a brushless doubly fed machine accounting for core loss

    , Article IET Electric Power Applications ; Volume 7, Issue 3 , 2013 , Pages 170-178 ; 17518660 (ISSN) Hashemnia, M. N ; Tahami, F ; Tavner, P ; Tohidi, S ; Sharif University of Technology
    2013
    Abstract
    In this study a steady-state equivalent circuit for a brushless doubly fed machine (BDFM), based upon earlier work, is introduced which takes account of core losses. Based upon some loss approximations, simple relationships have been derived, which show that the synchronous mode operation, in terms of core loss, of the BDFM is similar to the cascaded doubly fed machine. The slip-dependence of core loss resistances in the equivalent circuit has been investigated by applying energy conservation to derive machine steady-state torque-speed relations in the presence of core loss. Experimental speed measurements of the BDFM in the simple induction mode were used to identify the core loss... 

    Modeling, control and islanding detection of microgrids with passive loads

    , Article Proceedings of EPE-PEMC 2010 - 14th International Power Electronics and Motion Control Conference, 6 September 2010 through 8 September 2010 ; September , 2010 , Pages T11107-T11112 ; 9781424478545 (ISBN) Popov, M ; Karimi, H ; Nikkhajoei, H ; Terzija, V ; Sharif University of Technology
    2010
    Abstract
    This paper presents a control scheme for microgrids with passive loads. The existing control techniques for distributed generation systems are designed to operate either in the grid-connected or in the islanded mode. In the grid-connected mode of operation, a currentcontrolled scheme based on d-q variables is used for the regulation of real and reactive powers of the converter. In the islanded mode of operation, the converter is controlled in the voltage-controlled mode. This paper deals with the modeling of both control schemes. Furthermore, reconnection from the islanded mode to the grid-connected mode based on the use of adequate Phase-Locked Loops (PLLs) has been demonstrated  

    An analytical framework for operational reliability studies of highly wind integrated power systems

    , Article 2016 International Conference on Probabilistic Methods Applied to Power Systems, PMAPS 2016 - Proceedings, 16 October 2016 through 20 October 2016 ; 2016 ; 9781509019700 (ISBN) Parvini, Z ; Abbaspour, A ; Fotuhi Firuzabad, M ; Moeini Aghtaie, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2016
    Abstract
    This paper presents a new framework for evaluating contribution of wind farms in operational reliability level of power systems. In this regard, at first, it provides a short-term analytical model well designed to represent intermittent and uncertain nature of wind power. Combining the attained multi-state model of wind farms with the other committed generating units, operational risk of the system is evaluated. The concept of Pennsylvania-New Jersey-Maryland (PJM), previously developed to assess the short-term/mid-term reliability of conventional generating units, is revisited in this paper to more practically incorporate wind farms in reliability studies of the power system. The proposed... 

    Autonomous operation of a hybrid AC/DC microgrid with multiple interlinking converters

    , Article IEEE Transactions on Smart Grid ; Volume 9, Issue 6 , 2018 , Pages 6480-6488 ; 19493053 (ISSN) Peyghami, S ; Mokhtari, H ; Blaabjerg, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2018
    Abstract
    Applying conventional dc-voltage-based droop approaches for hybrid ac/dc microgrids interconnected by a single interlinking converter (IC) can properly manage the power flow among ac and dc subgrids. However, due to the effect of line resistances, these approaches may create a circulating power as well as overstressing the ICs in the case of employing multiple ICs for interconnecting the ac and dc subgrids. This paper proposes an autonomous power sharing approach for hybrid microgrids interconnected through multiple ICs by introducing a superimposed frequency in the dc subgrid. Hence, a suitable droop approach is presented to manage the power among the dc and ac sources as well as ICs. The...