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    CLB-based detection and correction of bit-flip faults in SRAM-based FPGAs

    , Article 2007 IEEE International Symposium on Circuits and Systems, ISCAS 2007, New Orleans, LA, 27 May 2007 through 30 May 2007 ; 2007 , Pages 3696-3699 ; 02714310 (ISSN) Zarandi, H. R ; Miremadi, S. G ; Argyrides, C ; Pradhan, D. K ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2007
    Abstract
    This paper presents a bit-flip tolerance in SRAM-based FPGAs which suffers from high energy particles, alpha and neutrons in the atmosphere. For each of protections, the applicability, efficiency and implementation issues are discussed. Moreover, the area, the power and the protection capability of the methods are mentioned and compared with previous work Based on the results of experiments and their analysis, one method is selected as best one. The selected method is much better than previous work e.g., duplication with comparison, triple modular redundancy which impose two and three area and power overheads, respectively. © 2007 IEEE  

    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  

    Online data loss in substation automation systems

    , Article IEEE Power and Energy Society General Meeting, 26 July 2015 through 30 July 2015 ; Volume 2015-September , 2015 ; 19449925 (ISSN) ; 9781467380409 (ISBN) Falahati, B ; Vakilian, M ; Fu, Y ; Sharif University of Technology
    IEEE Computer Society  2015
    Abstract
    The study presented in this paper investigated online data loss in a substation automation system (SAS) under network faults or failures. Online data loss refers to the amount of data that become inaccessible when a failure occurs in the SAS. It is a mathematical index related to the network's topology and architecture, and the calculation of which requires knowledge of the physical characteristics of SAS elements. The elements that record data were identified, and then the online data lost due to failures in those elements were determined. Also, as a case study, a typical SAS was examined under various states of failure, and the online data loss occurring under each scenarios was calculated... 

    Reliability assessment of an automated distribution system

    , Article IET Generation, Transmission and Distribution ; Volume 1, Issue 2 , 2007 , Pages 223-233 ; 17518687 (ISSN) Kazemi, S ; Fotuhi Firuzabad, M ; Billinton, R ; Sharif University of Technology
    2007
    Abstract
    Automation can greatly enhance distribution-network reliability by speeding up service restoration and thus significantly reduce customer-outage time. The paper presents an approach to assess quantitatively the adequacy of a particular automated distribution scheme designated as the 'low interruption system' (LIS). Owing to the use of a high-speed communication system and line sensors, this automated scheme can reduce drastically the number of interruptions, the service interruption time and also the area affected by the fault. This scheme provides a simple and cost-effective way to automate distribution systems in which the remotely controlled switches speed up isolation of faulted sections... 

    A new wavelet-based method for detection of high impedance faults

    , Article 2005 International Conference on Future Power Systems, Amsterdam, 16 November 2005 through 18 November 2005 ; Volume 2005 , 2005 ; 9078205024 (ISBN); 9789078205029 (ISBN) Mokhtari, H ; Aghatehrani, R ; Sharif University of Technology
    IEEE Computer Society  2005
    Abstract
    Detecting high impedance faults is one of the challenging issues for electrical engineers. Over-current relays can only detect some of the high impedance faults. Distance relays are unable to detect faults with impedance over 100Ω. In this paper, by using an accurate model for high impedance faults, a new wavelet-based method is presented. The proposed method, which employs a 3 level neural network system, can successfully differentiate high impedance faults from other transients. The paper also thoroughly analyzes the effect of choice of mother wavelet on the detection performance. Simulation results which are carried out using PSCAD/EMTDC software are summarized  

    Application of synchronised phasor measurements to wide-area fault diagnosis and location

    , Article IET Generation, Transmission and Distribution ; Vol. 8, issue. 4 , 2014 , pp. 716-729 ; ISSN: 17518687 Salehi-Dobakhshari, A ; Ranjbar, A. M ; Sharif University of Technology
    Abstract
    This study introduces a novel approach to power system fault diagnosis by synchronised phasor measurements. Conventionally, faults are diagnosed through the status of protective relays and circuit breakers which are activated following a fault. However, the hidden failures of the protection system has itself often been among the main suspects of partial or widespread blackouts. This study proposes an alternative fault diagnosis approach independent of the function of the protection system. An analytical method is introduced for power system fault diagnosis using dispersed synchronised measurements and bus impedance matrix (Zbus). Fault inception is first detected by local phasor measurement... 

    Effects of wind turbines on voltage profile

    , Article International Aegean Conference on Electrical Machines and Power Electronics, ACEMP 2011 and Electromotion 2011 Joint Conference ; Sept , 2013 , Pages 64-68 ; 9781467350037 (ISBN) Abedinzadeh, T ; Ehsan, M ; Afsharirad, H ; Nazaraliloo, M ; Sharif University of Technology
    2013
    Abstract
    For distribution grids connected wind power generation, voltage quality is an important issue for the system planning purpose. The operation of wind turbines in the distribution networks may affect the voltage quality offered to the consumers. One of the most important considerations is the effect on the voltage profile, i.e. the induced slow voltage variations, which are the subject of this paper. The wind turbines can be operated in two modes: constant-speed and variable-speed. Each one of these cases has different impact on steady state voltage of distribution grids. For evaluation of these impacts, we have simulated SCIG generator that works in constant-speed operation and DFIG generator... 

    Availability comparison of various power substation automation architectures

    , Article IEEE Transactions on Power Delivery ; Volume 28, Issue 2 , 2013 , Pages 566-574 ; 08858977 (ISSN) Hajian Hoseinabadi, H ; Sharif University of Technology
    2013
    Abstract
    This study aims at quantitatively assessing the availability indices of various substation automation systems. In order to illustrate the proposed technique, first, nine types of substation automation architectures are reviewed. The reliability block diagrams of various substation automation architectures are then developed. Subsequently, comparative studies are performed to demonstrate the most reliable architectures in comparison with the others. The results obtained by the proposed approach show the impact of repair on availability indices of the automation system. Finally, different sensitivity analyses are conducted for all architectures, where the impact of varying availability of all... 

    Mechanical force optimization on superconductor element of shield-type superconducting FCLs

    , Article 2012 3rd Power Electronics and Drive Systems Technology, PEDSTC 2012, 15 February 2012 through 16 February 2012 ; February , 2012 , Pages 495-499 ; 9781467301114 (ISBN) Hekmati, A ; Vakilian, M ; Fardmanesh, M ; Sharif University of Technology
    2012
    Abstract
    Superconducting fault current limiter (SFCL) is classified in the category of most efficient fault current limiters. Inductive shield-type SFCLs use bulk superconductor rings in their structure. At the fault occurrence, the induced current in the superconductor ring causes high mechanical forces on the ring. In the preliminary fabricated prototypes of this work, this mechanical force caused several damages to the superconductor element. Thus in this paper an analytical method is introduced to yield the main design parameters of the shield-type SFCL to ensure the sufficient mechanical withstand capability of the superconductor ring employed in this design. A prototype SFCL of this type is... 

    A new algorithm for fault location on transmission lines by optimal PMU placement

    , Article International Transactions on Electrical Energy Systems ; Volume 25, Issue 10 , 2015 , Pages 2071-2086 ; 20507038 (ISSN) Rezaei Jegarluei, M ; Salehi Dobakhshari, A ; Ranjbar, A. M ; Tayebi, A ; Sharif University of Technology
    John Wiley and Sons Ltd  2015
    Abstract
    In this paper, the problem of placing a minimum number of phasor measurement units (PMUs) in a transmission system is considered so that faults on all lines of the network can be diagnosed and located irrespective of their locations. For this purpose, a PMU placement algorithm is applied to calculate the required data for impedance-based fault location of any fault line in the network, achieving the full potential of the circuit laws throughout the system. Another algorithm is then proposed to compute the voltage and current values of the fault line for fault-location purposes. Moreover, as many networks are already equipped with PMUs, the proposed algorithm makes it possible to locate... 

    Grid-fault ride-through analysis and control of wind turbines with doubly fed induction generators

    , Article Electric Power Systems Research ; Volume 80, Issue 2 , February , 2010 , Pages 184-195 ; 03787796 (ISSN) Rahimi, M ; Parniani, M ; Sharif University of Technology
    2010
    Abstract
    This paper deals with the low voltage ride-through (LVRT) control of wind turbines with doubly fed induction generators (DFIGs) under symmetrical voltage dips. The investigation first develops a mathematical formula for the rotor current and rotor voltage when DFIG is subjected to a symmetrical voltage dip. From the analysis, the reasons of rotor inrush current and factors influencing it are inferred. Then, a control scheme enhancing the wind turbine LVRT capability is designed and simulated. The proposed control scheme consists of a nonlinear control strategy applied to the rotor-side converter and a dc-link voltage control applied to the grid-side converter. It improves the damping of DFIG... 

    A reconfigurable fault-tolerant routing algorithm to optimize the network-on-chip performance and latency in presence of intermittent and permanent faults

    , Article Proceedings - IEEE International Conference on Computer Design: VLSI in Computers and Processors ; 2011 , Pages 433-434 ; 10636404 (ISSN) ; 9781457719523 (ISBN) Jabbarvand Behrouz, R ; Modarressi, M ; Sarbazi Azad, H ; Sharif University of Technology
    Abstract
    As the semiconductor industry advances to the deep sub-micron and nano technology points, the on-chip components are more prone to the defects during manufacturing and faults during system operation. Consequently, fault tolerant techniques are essential to improve the yield of modern complex chips. We propose a fault-tolerant routing algorithm that keeps the negative effect of faulty components on the NoC power and performance as low as possible. Targeting intermittent faults, we achieve fault tolerance by employing a simple and fast mechanism composed of two processes: NoC monitoring and route adaption. Experimental results show the effectiveness of the proposed technique, in that it offers... 

    Technique for online tracking of a utility harmonic impedance using by synchronising the measured samples

    , Article IET Generation, Transmission and Distribution ; Volume 10, Issue 5 , 2016 , Pages 1240-1247 ; 17518687 (ISSN) Zebardast, A ; Mokhtari, H ; Sharif University of Technology
    Institution of Engineering and Technology 
    Abstract
    Utility harmonic impedance estimation is an important stage for the study and control of electrical networks power quality such as harmonic sharing determination between a utility and a customer at a point of common coupling (PCC). In this estimation, non-invasive methods, as compared with invasive methods, are more desirable since they do not need to apply intentional disturbances to the power network and can work based on natural load fluctuations. The only concern about such methods is the method accuracy. These methods require simultaneous and synchronous measurements of the voltage and current at the PCC. However, one of the causes of error in the utility harmonic impedance measurement... 

    New method for assessing the utility harmonic impedance based on fuzzy logic

    , Article IET Generation, Transmission and Distribution ; Volume 11, Issue 10 , 2017 , Pages 2448-2456 ; 17518687 (ISSN) Zebardast, A ; Mokhtari, H ; Sharif University of Technology
    Abstract
    This study proposes a novel non-invasive method for estimating the utility harmonic impedance. Since the major concern about non-invasive methods is the dependency of the accuracy of the results on background harmonic fluctuations, proper measured samples are selected using a three-point data selection technique to increase the method accuracy. Then, a new non-invasive method for the evaluation of the utility harmonic impedance at a point of common coupling (PCC) based on fuzzy logic is presented. In the proposed method, fuzzy logic is applied to the constrained recursive least squares algorithm (CRLS) by designing a set of fuzzy if-then rules. Due to the changes in the quantities at a... 

    A new noise-immune method to detect protective CT saturation and its release instants

    , Article 2016 IEEE International Conference on Power and Renewable Energy, ICPRE 2016, 21 October 2016 through 23 October 2016 ; 2017 , Pages 284-287 ; 9781509030682 (ISBN) Borzooy, A ; Vakilian, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2017
    Abstract
    CT saturation is a phenomenon that can cause inaccurate fault current measurement and may result in related protective relay failure to block the high current flow under a fault condition in a power system. Hence, it is required to develop a method to detect occurrence of CT saturation with a good accuracy under presence of noise in a power system. In this paper, a new method having the afore-mentioned characteristics is presented. The main benefit of exploiting the introduced approach here for detecting CT saturation is its high level of reliability as well as its reasonable operational speed in CT saturation detection. In other words, these two properties are implemented to this method.... 

    Optimal robust first-order frequency controller design for DFIG-based wind farm utilising 16-plant theorem

    , Article IET Renewable Power Generation ; Volume 12, Issue 3 , 2018 , Pages 298-310 ; 17521416 (ISSN) Toulabi, M. R ; Salehi Dobakhshari, A ; Ranjbar, A. M ; Sharif University of Technology
    Institution of Engineering and Technology  2018
    Abstract
    With increasing the share of wind farms in generation profile, their contribution to frequency regulation has become crucial. This study presents an optimal robust first-order frequency controller in the wind farms, which collectively emulates the inertial response as well as governor droop of synchronous generators. To account for various uncertainties associated with system inertia, damping, and doubly-fed induction generator (DFIG)-based wind turbine's parameters, the robustness of controller is verified through the 16-plant theorem. An analytic method based on the small-signal model of the system is utilised to determine the stability region of the first-order controller. To evaluate the... 

    Fault detection and protection strategy for islanded inverter-based microgrids

    , Article IEEE Journal of Emerging and Selected Topics in Power Electronics ; 2019 ; 21686777 (ISSN) Zarei, S. F ; Mokhtari, H ; Blaabjerg, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    This paper proposes a fault detection and protection strategy for islanded inverter-based microgrids (IBMGs). Reliable and accurate protection is one of the main challenges in the proliferation of modern microgrids (MGs). Considering the limited fault current of the voltage-frequency controlled inverter-based distributed energy resources (VF-IBDERs), the protection is more challenging in islanded IBMGs. In this regard, the control scheme of VF-IBDER with a current limiting strategy plays an important role. Due to the limited fault currents close to the converter nominal current, the conventional fault detection methods do not work properly. In addition, bi-directional fault currents worsen... 

    Fault detection and protection strategy for islanded inverter-based microgrids

    , Article IEEE Journal of Emerging and Selected Topics in Power Electronics ; 2019 ; 21686777 (ISSN) Zarei, F ; Mokhtari, H ; Blaabjerg, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    This paper proposes a fault detection and protection strategy for islanded inverter-based microgrids (IBMGs). Reliable and accurate protection is one of the main challenges in the proliferation of modern microgrids (MGs). Considering the limited fault current of the voltage-frequency controlled inverter-based distributed energy resources (VF-IBDERs), the protection is more challenging in islanded IBMGs. In this regard, the control scheme of VF-IBDER with a current limiting strategy plays an important role. Due to the limited fault currents close to the converter nominal current, the conventional fault detection methods do not work properly. In addition, bi-directional fault currents worsen... 

    High-impedance fault detection using multi-resolution signal decomposition and adaptive neural fuzzy inference system

    , Article IET Generation, Transmission and Distribution ; Volume 2, Issue 1 , 2008 , Pages 110-118 ; 17518687 (ISSN) Etemadi, A. H ; Sanaye Pasand, M ; Sharif University of Technology
    2008
    Abstract
    High-impedance faults (HIFs) on distribution systems create unique challenges to protection engineers. HIFs do not produce enough fault current to be detected by conventional overcurrent relays or fuses. A method for HIF detection based on the nonlinear behaviour of current waveforms is presented. Using this method, HIFs can be distinguished successfully from other similar waveforms such as nonlinear load currents, secondary current of saturated current transformers and inrush currents. A wavelet multi-resolution signal decomposition method is used for feature extraction. Extracted features are fed to an adaptive neural fuzzy inference system (ANFIS) for identification and classification.... 

    Simulation of superconductive fault current limiter (SFCL) using modular neural networks

    , Article IECON 2006 - 32nd Annual Conference on IEEE Industrial Electronics, Paris, 6 November 2006 through 10 November 2006 ; 2006 , Pages 4415-4419 ; 1424401364 (ISBN); 9781424401369 (ISBN) Makki, B ; Sadati, N ; Sohani, M ; Sharif University of Technology
    2006
    Abstract
    Modular Neural Networks have had significant success in a wide range of applications because of their superiority over single non-modular ones in terms of proper data representation, feasibility of hardware implementation and faster learning. This paper presents a constructive multilayer neural network (CMNN) in conjunction with a Hopfield model using a new cost function to simulate the behavior of superconductive fault current limiters (SFCLs). The results show that the proposed approach can efficiently simulate the behavior of SFCLs. ©2006 IEEE