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power-losses
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RCD snubber design based on reliability consideration: A case study for thermal balancing in power electronic converters
, Article Microelectronics Reliability ; Volume 88-90 , 2018 , Pages 1311-1315 ; 00262714 (ISSN) ; Zarghani, M ; Kaboli, S ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
In a turn-off RCD snubber, the capacitor value is usually optimized in order to minimize the power dissipated in the switch and snubber circuit. However, it may not be the best value of the snubber capacitor from the reliability point of view. In this paper, the capacitor value is optimized based on reliability considerations. Proposed method presents a new design to achieve the maximum reliability for the set of switch and its snubber. Mathematical analysis of the proposed method is conducted in MATLAB environment. Also, the experimental results are presented for validity of the theoretical analysis. © 2018 Elsevier Ltd
On the rolling contact problem of two elastic solids with graded coatings
, Article International Journal of Mechanical Sciences ; Volume 64, Issue 1 , 2012 , Pages 62-81 ; 00207403 (ISSN) ; Alinia, Y ; Adibnazari, S ; Sharif University of Technology
2012
Abstract
In this study, the rolling contact problem of two elastically similar cylinders coated with functionally graded materials is investigated. The singular integral equations approach is utilized to extract the governing equations of the problem. The governing equations are discretized into systems of algebraic equations by virtue of the Gauss-Chebyshev integration method. Comprehensive parametric study is performed to examine the effects of mechanical properties, coating thickness and external loads on the surface stress components, stick/slip transition, creep ratio and power loss. This study aimed to emphasize the capability of graded materials in improving the rolling contact fatigue of...
Effects of resistive loads and tire inflation pressure on tire power losses and CO2 emissions in real-world conditions
, Article Applied Energy ; Volume 157 , November , 2015 , Pages 974-983 ; 03062619 (ISSN) ; Nasiri, S ; Karkhaneh, V ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
Considerable portion of energy losses in a vehicle traced to tire. Energy losses in a tire are due to tire longitudinal slip as well as rolling resistance. Hence, both of aforementioned factors must take into the consideration to study the tire energy loss. Present paper aims to investigate the power losses in tires and to examine influence of road conditions and tire inflation pressure on them. To cover the real-world conditions, experiments were done on a gasoline-fueled passenger vehicle on an urban highway along two routes with same length and opposite gradients to comprise the change of road conditions. Then, by use of engine performance model which is prepared in dynamometer...
Visibility of electric distribution utility performance to manage loss and reliability indices
, Article Journal of Electrical Engineering and Technology ; Volume 12, Issue 5 , 2017 , Pages 1764-1776 ; 19750102 (ISSN) ; Ghazizadeh, M. S ; Kermanshah, A ; Haghifam, M. R ; Sharif University of Technology
Abstract
To achieve economic stability, distribution Company as an economic institution should be managed by various processes. In this way, knowledge of different processes is the first step. Furthermore, expectations, outputs, requirement data, and sub-processes should be extracted and determined. Accordingly, to assign the performance responsibility of each process, the decision making points must be introduced and, the deviation or change in set-points should be investigated into processes. Also, the performance of processes could be monitored by introducing of the sub-indictors. In this study, a practical method is presented for monitoring of reliability and power loss indices from viewpoint...
Determining and optimizing power loss reduction in distribution feeders due to Distributed generation
, Article 2006 IEEE PES Power Systems Conference and Exposition, PSCE 2006, Atlanta, GA, 29 October 2006 through 1 November 2006 ; 2006 , Pages 1914-1918 ; 142440178X (ISBN); 9781424401789 (ISBN) ; Parniani, M ; Sharif University of Technology
2006
Abstract
One of the beneficial impacts of Distributed generation (DG) units on electrical network is power loss reduction in the distribution feeder on which DG is located. In this paper the effect of DG on power losses of a distribution feeder with a combination of uniformly distributed and lumped loads is investigated, and a mathematical model of power loss reduction as a function of DG and the feeder parameters is extracted. Then, based on the derived formula, optimum conditions of utilizing and locating the DG units are obtained. © 2006 IEEE
Rolling Contact Analysis of a Cylinder with a FGM Coated Half-Plane
, Ph.D. Dissertation Sharif University of Technology ; Adibnazari, Saeed (Supervisor)
Abstract
This study focuses on the mathematical modeling of the rolling contact problem of an FGM coating-substrate system. The first part presents the uncoupled rolling contact problem of an FGM coated half-plane under the assumption of a central stick zone with two slip zones of the same sign. Considering all possible stick/slip scenarios, the fully coupled rolling contact problem of a graded coating is given in the second part. Finally, the rolling contact problem of two elastically similar cylinders with graded coatings will be discussed. Generally, all mentioned problems can be solved in three consecutive steps. First, the governing equations of the relevant rolling contact problem are...
Optimal Placement of Active Filters in a Power System
, M.Sc. Thesis Sharif University of Technology ; Mokhtari, Hossein (Supervisor)
Abstract
The extensive use of nonlinear loads such as motor drives and new generation of home appliances has caused a deterioration of power quality in power systems. The use of active power filters due to the fast variation of the loads has been recommended by power engineering. In this method, the harmonic profiles are controlled by applying active filters in a distribution feeder. Optimal placement of active filters in a distribution system due to the increase of harmonic generation loads has attracted researchers. However placement of each filter is the major concern that researchers face. In this paper, a new objective function is introduced to determine the optimal number and location of active...
Optimal distributed generation allocation in distribution network using Hereford Ranch algorithm
, Article ICEMS 2005: 8th International Conference on Electrical Machines and Systems, Nanjing, 27 September 2005 through 29 September 2005 ; Volume 2 , 2005 , Pages 916-918 ; 7506274078 (ISBN); 9787506274074 (ISBN) ; Vakilian, M ; Ehsan, M ; Sharif University of Technology
IEEE Computer Society
2005
Abstract
The necessity for flexible electric systems, energy saving, loss reducing and environmental impact are providing Impetus to the development of Distributed Generation (DG). DG Includes the application of small generators, scattered throughout a power system, to provide the electric power needed by electrical customer. Such locally distributed generation, has several merits from the viewpoint of environmental restriction and location limitations, as well as transient and voltage stability In the power system. The exact solution of the DG allocation can be obtained by a complete enumeration of all feasible combinations of sites and sizes of DGs In the network. The number of alternatives could...
State Plane Analysis and Optimization of CLLC Resonant Converter for Bidirectional EV Charger
, Ph.D. Dissertation Sharif University of Technology ; Tahami, Farzad (Supervisor) ; Schanen, Jean-Luc (Supervisor)
Abstract
As more renewables step in, the ongoing change will be drastic for the electrical grid. The energy sector must find new ways to balance energy production and consumption. Electric vehicle (EV) batteries are by far the most cost-efficient form of energy storage since they require no additional investments in hardware. A bidirectional EV charger is a new technology that enables energy to be pushed back to the power grid and auxiliary loads from the battery. The electrical requirements of the EV charger are examined in detail to find an appropriate power electronics converter to meet all the requirements. The CLLC resonant converter is a promising candidate for high efficient, bidirectional...
Effects of resistive loads and tire inflation pressure on tire power losses and CO2 emissions in real-world conditions
,
Article
Applied Energy
;
2015
;
ISSN: 03062619
; Nasiri, S
; Karkhaneh, V
;
Sharif University of Technology
Abstract
Considerable portion of energy losses in a vehicle traced to tire. Energy losses in a tire are due to tire longitudinal slip as well as rolling resistance. Hence, both of aforementioned factors must take into the consideration to study the tire energy loss. Present paper aims to investigate the power losses in tires and to examine influence of road conditions and tire inflation pressure on them. To cover the real-world conditions, experiments were done on a gasoline-fueled passenger vehicle on an urban highway along two routes with same length and opposite gradients to comprise the change of road conditions. Then, by use of engine performance model which is prepared in dynamometer...
An enhanced hybrid modular multilevel converter for improved performance
, Article IEEE Transactions on Power Electronics ; 2018 ; 08858993 (ISSN) ; Ravanji, M. H ; Parniani, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
This paper proposes an enhanced hybrid modular multilevel converter (MMC), which utilizes a combination of halfbridge submodules (HBSM) and at least one full-bridge submodule (FBSM). In the proposed structure, FBSMs work with half of the HBSMs nominal voltage in each arm. Due to the presence of FBSMs, HBSMs switching frequency drops significantly, which reduces the converter power loss compared to half-bridge based MMCs. Furthermore, because of redundant FBSMs, (2N+1)-modulation can be employed to generate the output voltage without increasing the circulating current, thus the converter performance is improved notably. Besides, with the redundant FBSMs the converter can continue its...
Enhanced hybrid modular multilevel converter with improved reliability and performance characteristics
, Article IEEE Transactions on Power Electronics ; Volume 34, Issue 4 , 2019 , Pages 3139-3149 ; 08858993 (ISSN) ; Ravanji, M. H ; Parniani, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
This paper proposes an enhanced hybrid modular multilevel converter (MMC), which utilizes a combination of half-bridge submodules (HBSM) and at least one full-bridge submodule (FBSM). In the proposed structure, FBSMs work with half of the HBSMs nominal voltage in each arm. Due to the presence of FBSMs, HBSMs switching frequency drops significantly, which reduces the converter power loss compared to half-bridge based MMCs. Furthermore, because of redundant FBSMs, (2N + 1)-modulation can be employed to generate the output voltage without increasing the circulating current, thus, the converter performance is improved notably. Besides, with the redundant FBSMs, the converter can continue its...
Optimal reactive power dispatch considering TCPAR and UPFC
, Article IEEE EUROCON 2009, EUROCON 2009, St. Petersburg, 18 May 2009 through 23 May 2009 ; 2009 , Pages 577-582 ; 9781424438617 (ISBN) ; Khazali, A. H ; Zare, S ; Sharif University of Technology
2009
Abstract
Optimal Reactive Power Dispatch (ORPD) has a salient impact on decreasing the power loss of transmission lines and adjusting the voltage deviation. The parameters that are used for the ORPD are tap settings of transformers, voltages of generating plants and the output of compensating device such as capacitor banks and synchronous condensors. In this paper settings of FACTS devices are considered as additional parameters in solving the ORPD problem. Also the genetic algorithm has been used to find the optimal settings of the controlling parameters. The results of the ORPD have been obtained on a 30 bus IEEE network. © 2009 IEEE
Distribution system reconfiguration for loss reduction incorporating load and renewable generation uncertainties
, Article 2019 IEEE Texas Power and Energy Conference, TPEC 2019, 7 February 2019 through 8 February 2019 ; 2019 ; 9781538692844 (ISBN) ; Amini, M ; Modarresi, M. S ; Jafarishiadeh, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
A significant share of losses in power systems occurs in distribution network due to lower voltages and longer lines. On top of that, unbalanced operation causes additional losses in these networks. In recent years with the development of distributed generation connected to the distribution grid, the concern over frequency and intensity of unbalanced operation has risen. Reconfiguration of these distribution networks plays a significant role in power loss minimization and voltage quality enhancement. The uncertainty regarding grid-connected DG resources and net loads are among the critical factors that must be taken into account. To do so, in this paper a novel Fuzzy-based reconfiguration...
A reliability cost/worth approach to determine optimum switching placement in distribution systems
, Article 2005 IEEE/PES Transmission and DistributionConference and Exhibition - Asia and Pacific, Dalian, 15 August 2005 through 18 August 2005 ; Volume 2005 , 2005 , Pages 1-5 ; 0780391144 (ISBN); 9780780391147 (ISBN) ; Fotuhi Firuzabad, M ; Rashidi Nejad, M ; Sharif University of Technology
2005
Abstract
Nowadays automation in distribution systems is growing largely. Automated and remote controlled switches play prominent rules in automated distribution systems. By opening and closing these remote controlled switches in emergency states when a fault has been occurred we can manage fault and restoration process in order to minimize interruption time and costs. In the normal states feeder load management and power loss minimization can be controlled by these remote controlled switches. Finding optimum numbers and optimum locations for installing these switches is the main concern in this between. Up to now a number of algorithms have been developed for optimum switch placement. In this paper a...
A novel method to determine the best size of CHP for an energy hub system
, Article 2011 2nd International Conference on Electric Power and Energy Conversion Systems, EPECS 2011 ; 2011 ; 9781457708060 (ISBN) ; Ranjbar, A. M ; Safe, F ; IEEE; Power and Energy Society (IEEE PES); Abu Dhabi Water and Electricity Authority ; Sharif University of Technology
Abstract
Today, the interest on distributed generation has been increasing, especially due to technical development on generation systems that meet environmental and energy policy concerns. One of the most important distributed energy technologies is Combined Heat and Power (CHP). CHP is small and self-contained electric generation plan that can provide power for household applications, commercial or industrial facilities and hence its applications are overtly increasing. It can reduce power loss and enhance service reliability in distribution systems. One of the influential factors for the users is the purchasing cost of CHP which is largely dependent on its type, capacity and efficiency. Therefore...
An adaptive approach for PEVs charging management and reconfiguration of electrical distribution system penetrated by renewables
, Article IEEE Transactions on Industrial Informatics ; 2017 ; 15513203 (ISSN) ; Fotuhi Firuzabad, M ; Sharif University of Technology
Abstract
An adaptive approach for distribution system reconfiguration and charging management of plug-in electric vehicles (PEV) is presented in this study. A stochastic model predictive control is applied to stochastically, adaptively, and dynamically reconfigure the system, manage the incidental charging pattern of PEVs, and deal with the variable and uncertain power of renewable energy sources. The objective function of problem is minimizing daily operation cost of system. Herein, the geography of area is considered and the behavior of PEVs' drivers (based on their income level) is modeled with respect to the value of incentive and their hourly distance from each charging station. It is shown that...
An adaptive approach for PEVs charging management and reconfiguration of electrical distribution system penetrated by renewables
, Article IEEE Transactions on Industrial Informatics ; Volume 14, Issue 5 , May , 2018 , Pages 2001-2010 ; 15513203 (ISSN) ; Fotuhi Firuzabad, M ; Sharif University of Technology
IEEE Computer Society
2018
Abstract
An adaptive approach for distribution system reconfiguration and charging management of plug-in electric vehicles (PEV) is presented in this study. A stochastic model predictive control is applied to stochastically, adaptively, and dynamically reconfigure the system, manage the incidental charging pattern of PEVs, and deal with the variable and uncertain power of renewable energy sources. The objective function of problem is minimizing daily operation cost of system. Herein, the geography of area is considered and the behavior of PEVs' drivers (based on their income level) is modeled with respect to the value of incentive and their hourly distance from each charging station. It is shown that...
Modified artificial bee colony algorithm based on fuzzy multi-objective technique for optimal power flow problem
, Article Electric Power Systems Research ; Volume 95 , 2013 , Pages 206-213 ; 03787796 (ISSN) ; Hosseinian, S. H ; Ghazanfari, A ; Sharif University of Technology
2013
Abstract
This paper presents a fuzzy based modified artificial bee colony (MABC) algorithm to solve discrete optimal power flow (OPF) problem that has both discrete and continuous variables considering valve point effects. The OPF problem is formulated as a multi-objective mixed-integer nonlinear problem, where optimal settings of the OPF control variables for simultaneous minimization of total fuel cost of thermal units, total emission, total real power losses, and voltage deviation are obtained. The proposed approach is applied to the OPF problem on IEEE 30-bus and IEEE 118-bus test systems. The performance and operation of the proposed approach is compared with the conventional methods. The...
Design model of axial flow compressor for high temperature power plants by latest loss models
, Article 2011 Proceedings of the 3rd Conference on Thermal Power Plants, CTPP 2011, 18 October 2011 through 19 October 2011, Tehran ; 2011 ; 9781479905911 (ISBN) ; Jouybari, H. J ; Shahhoseini, M. R ; Rad, M ; Sharif University of Technology
2011
Abstract
Design models of axial flow compressor are developed for high temperature power plants with Closed Brayton Cycle for energy conversion. in recent years, many efforts have been done for modeling and predicting of performance of these compressors on different conditions of speed and pressure ratio because of costly empirical experiments, and still are developing. The models are based on a mean-line through-flow analysis for free-vortex flow, account for the profile, secondary, end wall and tip clearance losses in the cascades. In this work, models of Lieblein, Koch-Smith, Herrig, Johnsen-Bullock, Pollard-Gostelow, Aungier, Hunter-Cumpsty, Reneau are implemented to consider single stage...