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    A data collection scheme for reliability evaluation and assessment - A practical case in Iran

    , Article 2004 International Conference on Power System Technology, POWERCON 2004, 21 November 2004 through 24 November 2004 ; Volume 2 , 2004 , Pages 999-1004 ; 0780386108 (ISBN) Farrokhzad, D ; Fotuhi Friuzabad, M ; Gharahgozloo, H ; Sharif University of Technology
    2004
    Abstract
    Data collection is an essential element of reliability assessment and many utilities throughout the world have established comprehensive procedures for assessing the performance of their electric power systems. Data collection is also a constituent part of quantitative power system reliability assessment in which system past performance and prediction of future performance are evaluated. This paper presents an overview of the Iran electric power system data collection scheme and the procedure to its reliability analysis. The scheme contains both equipment reliability data collection procedure and structure of reliability assessment. The former constitutes generation, transmission and... 

    A note on the bounded fragmentation property and its applications in network reliability

    , Article European Journal of Combinatorics ; Volume 24, Issue 7 , 2003 , Pages 891-896 ; 01956698 (ISSN) Hajiaghayi, M. T ; Hajiaghayi, M ; Sharif University of Technology
    2003
    Abstract
    In this paper, we introduce a new property for graphs called bounded fragmentation, by which we mean after removing any set of at most k vertices the number of connected components is bounded only by a function of k. We demonstrate how bounded fragmentation can be used to measure the reliability of a network and introduce several classes of bounded fragmentation graphs. Finally, we pose some open problems related to this concept. © 2003 Elsevier Ltd. All rights reserved  

    Integration of clustering analysis and reward/penalty mechanisms for regulating service reliability in distribution systems

    , Article IET Generation, Transmission and Distribution ; Vol. 5, issue. 11 , 2011 , p. 1192-1200 ; ISSN: 17518687 Mohammadnezhad-Shourkaei, H ; Fotuhi-Firuzabad, M ; Billinton, R ; Sharif University of Technology
    Abstract
    This study proposes an approach for improving service reliability in the distribution network based on establishing competition among electric distribution utilities. The idea behind this approach is to categorise the utilities and compare the performance of utilities located in one cluster with the other members of the same cluster. The reward/penalty mechanism (RPM) as a quality regulating instrument is designed for each cluster and used to penalise the utilities with a performance worse than the benchmark and to reward them for providing a performance better than the benchmark. Based on the RPM, utilities located in one cluster compete to make more profit by serving customers in better... 

    Integration of clustering analysis and reward/penalty mechanisms for regulating service reliability in distribution systems

    , Article IET Generation, Transmission and Distribution ; Volume 5, Issue 11 , 2011 , Pages 1192-1200 ; 17518687 (ISSN) Mohammadnezhad Shourkaei, H ; Fotuhi Firuzabad, M ; Billinton, R ; Sharif University of Technology
    Abstract
    This study proposes an approach for improving service reliability in the distribution network based on establishing competition among electric distribution utilities. The idea behind this approach is to categorise the utilities and compare the performance of utilities located in one cluster with the other members of the same cluster. The reward/penalty mechanism (RPM) as a quality regulating instrument is designed for each cluster and used to penalise the utilities with a performance worse than the benchmark and to reward them for providing a performance better than the benchmark. Based on the RPM, utilities located in one cluster compete to make more profit by serving customers in better... 

    A new approach for the reliability-based robust design optimization of mechanical systems under the uncertain conditions

    , Article SAE Technical Papers, 10 April 2018 through 12 April 2018 ; Volume 2018-April , 2018 ; 01487191 (ISSN) Khodaygan, S ; Sharafi, M. H ; Sharif University of Technology
    SAE International  2018
    Abstract
    A mechanical system inherently affected by the conditions, factors, and parameters of uncertainties. Without including the uncertainty effects in the design procedure, the designs may not be robust and reliable. Robust design optimization (RDO) method is a procedure to find the insensitive design with respect to the variations. On the other hand, reliability is measured by the probability of satisfying a specific design criterion. Therefore, a reliable design is a design that satisfies the specified criteria even with some uncertainties in variables and parameters. Reliability-based design optimization (RBDO) is an optimization procedure that incorporates reliability requirements to find the... 

    Inverse reliability evaluation in power distribution systems

    , Article IEEE Transactions on Power Systems ; Volume 35, Issue 1 , 2020 , Pages 818-820 Sharifinia, S ; Rastegar, M ; Allahbakhshi, M ; Fotuhi Firuzabad, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2020
    Abstract
    In power distribution systems, sometimes, system reliability indices are available, where some components' reliability parameters are unknown. This letter presents the inverse reliability evaluation (IRE) problem in radial distribution systems to find unknown components' parameters from the known system reliability indices. To this end, a nonlinear system of equations is presented and solved. The solutions are analyzed in the RBTS bus 2 to verify the applicability of the proposed approach and to show the importance of the IRE problem. © 1969-2012 IEEE  

    Reliability study of HV substations equipped with the fault current limiter

    , Article IEEE Transactions on Power Delivery ; Volume 27, Issue 2 , 2012 , Pages 610-617 ; 08858977 (ISSN) Fotuhi Firuzabad, M ; Aminifar, F ; Rahmati, I ; Sharif University of Technology
    2012
    Abstract
    Of particular interest to restrict the short-circuit level of interconnected power systems is to exploit fault current limiter (FCL) technologies. FCLs let the system planners devise new reliable and rather economical substation configurations and provide the possibility of proposing a promising cost-effective and prompt solution to the fault current over duty problem in the existing substations. This paper attempts to assess reliability of substation architectures accommodating the FCL operation and, besides, numerically investigates the FCL's impacts on the substation reliability indices. In order to clarify the proposed approach, two case studies with and without FCL are analyzed and... 

    Identification of critical components in power systems: A game theory application

    , Article 52nd Annual Meeting on IEEE Industry Application Society, 2 October 2016 through 6 October 2016 ; 2016 ; 9781467386715 (ISBN) Pourahmadi, F ; Fotuhi Firuzabad, M ; Dehghanian, P ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc 
    Abstract
    As the electricity market undergoes continuous evolutions, along with the outdated nature of the grid, system operators would have to be able to more effectively manage the operation costs since waves of maintenance costs and equipment investments would be anticipated in the years to come. Strategic implementation of cost-effective reliability centered maintenance (RCM) approaches seems to be a key solution. This paper proposes an efficient method to assess the component criticality for the system overall reliability and further maintenance focuses. A solution concept of game theory, called Shapely Value, that is able to fairly identify the contribution of each single equipment to the system... 

    A study of the reliability of various types of the electric vehicles

    , Article 2012 IEEE International Electric Vehicle Conference, IEVC 2012 ; 2012 ; 9781467315623 (ISBN) Negarestani, S ; Ghahnavieh, A. R ; Mobarakeh, A. S
    2012
    Abstract
    The reliability Studies are done in order to determine the probability of functioning or availability of different engineering systems. These studies can also provide a basis for comparing different structures of a system and can be used as a tool to improve the system design. Also, reliability is an important consideration in the planning, design and operation of transit system. Since the issue of the reliability of electric vehicles has not been sufficiently and seriously evaluated yet, so in this paper, the reliability of the various types of these kinds of vehicles will be discussed and then the reliability indices of them will be compared with each other and with the conventional cars  

    Hybrid AC/DC microgrids flexible reliability index by using the axiomatic design concept

    , Article IET Generation, Transmission and Distribution ; Volume 14, Issue 23 , 2020 , Pages 5456-5462 Sabouhi, H ; Doroudi, A ; Fotuhi Firuzabad, M ; Bashiri, M ; Sharif University of Technology
    Institution of Engineering and Technology  2020
    Abstract
    With the capacity increase of large-scale DC renewable energy and DC loads, the reliability issues of hybrid AC/DC networks become increasingly prominent. On the other hand, a modern distribution network should also deliver power to individual customers based on their priority levels and the traditional reliability indices are not suitable for modern networks. Flexible reliability (FR) is a new concept that considers the loads' importance in the reliability evaluation of distribution grids. In this study, a novel comprehensive FR index is introduced for hybrid AC/DC networks. To determine the proposed index, power networks are modelled as a topological combination of edges and nodes. An... 

    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  

    A new formulation for power system reliability assessment with AC constraints

    , Article International Journal of Electrical Power and Energy Systems ; Vol. 56, issue , March , 2014 , p. 298-306 ; ISSN: 1420615 Safdarian, A ; Fotuhi-Firuzabad, M ; Aminifar, F ; Lehtonen, M ; Sharif University of Technology
    Abstract
    Recent investigations have revealed the significant role of reactive power in blackout events. The associated disturbances frequently emerge in the form of voltage instability and collapse. Due to the computational complexity of modeling and analysis of enormous contingencies, DC approximation of the power flow, without accounting the role of reactive power, is usually used to evaluate the contingencies and to mitigate the associated probable violations. This paper, at first, presents a linear power flow model based on an approximated version of AC power flow formulation. The proposed model is then used to develop an efficient reliability assessment approach which is capable of taking both... 

    Short term voltage-based risk assessment by incorporating reactive power adequacy

    , Article Ain Shams Engineering Journal ; Volume 7, Issue 1 , 2016 , Pages 131-141 ; 20904479 (ISSN) Rahimi, M ; Fotuhi Firuzabad, M ; Karimi, A ; Sharif University of Technology
    Ain Shams University  2016
    Abstract
    A risk-based approach for short term security assessment with voltage stability constraint is presented in this paper. This approach includes voltage-stability considerations in reactive power adequacy assessment of a composite power system. The proposed method is based on probabilistic criteria because deterministic risk criteria do not define consistently the true risk in the system. For risk calculation, in this paper, load and parametric uncertainties and system contingencies are considered. Then the effects of uncertainties and contingencies on bus voltage violation are calculated. The required reactive power is determined based on the calculated voltage violation in order to maintain... 

    Impacts of remote control switch malfunction on distribution system reliability

    , Article IEEE Transactions on Power Systems ; Volume 32, Issue 2 , 2017 , Pages 1572-1573 ; 08858950 (ISSN) Safdarian, A ; Farajollahi, M ; Fotuhi Firuzabad, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2017
    Abstract
    Remote control switches (RCSs) are often assumed to be fully reliable in reliability and cost/worth analyses. This assumption, however, overestimates their merits, thereby misguiding network owners about their optimal implementation. This letter extends the current reliability evaluation procedure to incorporate probability of RCS malfunctions. Then, the extended procedure is applied to a network equipped with a few RCSs. The numerical studies reveal that RCS malfunctions degrade their worth, which may even affect their optimal number and locations. © 1969-2012 IEEE  

    Wear-out failure of a power electronic converter under inversion and rectification modes

    , Article 11th Annual IEEE Energy Conversion Congress and Exposition, ECCE 2019, 29 September 2019 through 3 October 2019 ; 2019 , Pages 1598-1604 ; 9781728103952 (ISBN) Peyghami, S ; Davari, P ; Zhou, D ; F-Firuzabad, M ; Blaabjerg, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    The expected lifetime of a power electronic converter is limited by its fragile components such as semiconductor devices and capacitors. These components are prone to wear-out failures depending on the converter mission profile and component thermal characteristics. This paper explores the wear-out failure of the power converter semiconductor devices in inverting and rectifying modes of the converter using different power factors. The obtained results show the different wear-out characteristics of a converter under rectification, inversion, and also partial-inversion/rectification modes as well as when provides reactive power support. Moreover, this paper proposes B10 lifetime curves to... 

    Impact of distributed generation resources on customer interruption cost

    , Article 2004 International Conference on Power System Technology, POWERCON 2004, 21 November 2004 through 24 November 2004 ; Volume 1 , 2004 , Pages 856-861 ; 0780386108 (ISBN) Rajabi Ghahnavie, A ; Fotuhi Firuzabad, M ; Parniani, M ; Sharif University of Technology
    2004
    Abstract
    The electric power industry around the world is presently undergoing considerable changes with respect to structure, operation and regulation. Distributed generation is expected to play a major role in this new environment One the main benefits of DG is to enhance system reliability as it can restore power to the separated or bottle-necked part of distribution system in case of a contingency occurs. This paper presents an approach to examine and evaluates the applicability and customer interruption cost analysis in DG-connected distribution system in a specified planning horizon. The impacts on customer interruption cost reduction of different load growth rate, DG location and different... 

    Optimal reliable operation of hydrothermal power systems with random unit outages

    , Article IEEE Transactions on Power Systems ; Volume 18, Issue 1 , 2003 , Pages 279-287 ; 08858950 (ISSN) Amjady, N ; Farrokhzad, D ; Modarres, M ; Sharif University of Technology
    2003
    Abstract
    A new model for long-term operation of hydrothermal power systems is introduced and a method for obtaining an optimal solution is also developed. We assume that reservoir inflows and energy demand are stochastic and all units are exposed to random outages. The objective is to minimize the total cost of the system as well as the expected interruption cost of energy (EIC) during a given planning horizon. This goal is reached through determination of hydroplant discharges, thermal units energy output, and the system reliability level simultaneously. In fact, we integrate long-term hydrothermal system operation planning and system reliability determination in a unified model. Since the resulting... 

    Reliability consideration in optimization of cascaded hydrothermal power systems

    , Article International Journal of Power and Energy Systems ; Volume 23, Issue 1 , 2003 , Pages 6-14 ; 10783466 (ISSN) Modarres, M ; Farrokhzad, D ; Sharif University of Technology
    2003
    Abstract
    This article investigates optimization of long-term operation of hydrothermal power systems consisting of cascaded reservoirs. Due to stochasticity of reservoir inflows, demand for energy, and unit forced outages, the uncertainty of this system is so significant that reliability of demand satisfaction becomes an indispensable component of the modelling process. On the other hand, existence of stochastic parameters, especially in the case of cascaded reservoirs, makes the problem very difficult to solve by applying existing optimization techniques. A hybrid genetic algorithm with dynamic tuning of its control parameters is developed that incorporates real number encoding and an analytical... 

    Optimal Reliable Operation of Hydrothermal Power Systems with Random Unit Outages

    , Article IEEE Power Engineering Review ; Volume 22, Issue 11 , 2002 , Pages 59- ; 02721724 (ISSN) Amjady, N ; Farrokhzad, D ; Modarres, M ; Sharif University of Technology
    2002
    Abstract
    A new model for long-term operation of hydrothermal power systems is introduced, and a method for obtaining an optimal solution is developed. We assume both reservoir inflows and energy demand are stochastic and all units are exposed to random outages. The objective is to minimize the total cost of the system as well as the expected interruption cost of energy (EIC) during a given planning horizon. This goal is reached through simultaneous determination of hydro plant discharges, thermal units energy output, and the system reliability level. Long-term hydrothermal system operation planning and system reliability determination are integrated in a unified model. Since the resulting model is a... 

    Reliability and component importance analysis of substation automation systems

    , Article International Journal of Electrical Power and Energy Systems ; Volume 49 , July , 2013 , Pages 455–463 ; 01420615 (ISSN) Hajian Hoseinabadi, H ; Sharif University of Technology
    Abstract
    This paper aims to present a comprehensive technique to quantitatively assess the reliability of substation automation systems. The technique is based on the tie-sets methodology. In order to demonstrate the application of the proposed technique, a variety of substation automation architectures is first introduced. The associated reliability block diagrams as well as the exact system reliability are then given. The impacts and the degree of importance of various components on the reliability of substation automation systems are presented. Two suitable measures of importance are selected. The first is the Birnbaum's measure used to determine the bottleneck of the system reliability. The...