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    Effects of skewing on torque ripples for brushless doubly-fed machine

    , Article International Review of Electrical Engineering ; Volume 4, Issue 6 , 2009 , Pages 1283-1293 ; 18276660 (ISSN) Gorgin, H ; Sotoodeh, P ; Oraee, H ; Sharif University of Technology
    Abstract
    In this paper, analytical expressions are presented to describe the stator and rotor slotting effects on the distribution of Brushless Doubly-Fed Machine's quantities. The effects of rotor slot and loop skewing on the produced torque ripples are then investigated by means of an analytical model considering skew. Torque ripples have considerable effects in the machine operation especially on its starting process and avoid machine from successful starting in some instances. The cogging torque and distortion of the sinusoidal distribution of the magnetic flux density in the air gap, are two principle sources of torque ripples in Brushless Doubly-Fed Machine that are studied. © 2009 Praise... 

    Wind tunnel study of the effect zigzag tape on aerodynamics performance of a wind turbine airfoil

    , Article Journal of Advanced Research in Fluid Mechanics and Thermal Sciences ; Volume 41, Issue 1 , 2018 , Pages 1-9 ; 22897879 (ISSN) Jafari Gahraz, R ; Lazim, T.M ; Darbandi, M ; Sharif University of Technology
    Penerbit Akademia Baru  2018
    Abstract
    A wind tunnel study was performed on the FFA-W-3-270 airfoil, which form a segment of a 1.25 MW wind turbine blade, to examine the effect of fixed roughness height and position using a zigzag tape boundary layer trip strip. Tests were conducted at a Reynolds number of 1×106 over a wide range of angles of attack. The zigzag tape, as an artificial roughness device, not only triggers a premature transition in the flow whereby laminar flow regimes change to turbulent, but also increases the momentum thickness of the turbulent boundary layer and change the airfoil camber. The 60° zigzag tape of 0.5 mm and 1 mm height was placed on the suction side of the airfoil at different chord wise locations.... 

    Unsteady aerodynamic analysis of different multi-MW horizontal axis wind turbine blade profiles on SST K-ω model

    , Article Green Energy and Technology ; 2018 , Pages 17-30 ; 18653529 (ISSN) Radmanesh, A. R ; Abbaspour, M ; Soltani, M. R ; Sharif University of Technology
    Springer Verlag  2018
    Abstract
    In this study, in order to indicate the best airfoil profile for the different sections of a blade, five airfoils including S8xx, FFA, and AH series were studied. Among the most popular wind power blades for this application were selected, in order to find the optimum performance. Nowadays, modern wind turbines are using blades with multi-airfoils at different sections. On the large scale profile, SST K-ω model with different wind speed at large-scale profile was applied to the simulation of horizontal axis wind turbines (HAWT). The aerodynamic simulation was accomplished using the computational fluid dynamic (CFD) method based on the finite volume method. The governing equations applied in... 

    Load profile flattening considering EV’s initial and final SoC and arrival and departure times

    , Article Iranian Journal of Electrical and Electronic Engineering ; Volume 18, Issue 4 , 2022 ; 17352827 (ISSN) Bagheri, V ; Ehyaei, A. F ; Haeri, M ; Sharif University of Technology
    Iran University of Science and Technology  2022
    Abstract
    In distribution networks, failure to smooth the load curve leads to voltage drop and power quality loss. In this regard, electric vehicle batteries can be used to smooth the load curve. However, to persuade vehicle owners to share their vehicle batteries, we must also consider the owners' profits. A challenging problem is that existing methods do not take into account the vehicle owner demands including initial and final states of charge and arrival and departure times of vehicles. Another problem is that battery capacity of each vehicle varies depending on the type of vehicle; which leads to uncertainties in the charging and discharging dynamics of batteries. In this paper, we propose a... 

    Prediction of transition point on an oscillating airfoil using Neural network

    , Article 2007 5th Joint ASME/JSME Fluids Engineering Summer Conference, FEDSM 2007, San Diego, CA, 30 July 2007 through 2 August 2007 ; Volume 2 FORA, Issue PART A , July , 2007 , Pages 33-39 ; 0791842886 (ISBN); 9780791842881 (ISBN) Soltani, M. R ; Seddighi, M ; Masdari, M ; Sharif University of Technology
    2007
    Abstract
    Dynamic Neural network was used to minimize the amount of data required to predict the location of transition point on a 2-D oscillatory wing. For this purpose, various experimental tests were carried out on a section of a 660kw wind turbine blade. A multi layer non linear perceptrons network was trained using the output signals of four hot films attached on the upper surface of the model. Results show that using only 50% of the test data, the trained network was able to the transition point with an acceptable accuracy. Moreover, the method can predict the transition points at any position of the wing surface for different Reynolds numbers, amplitudes and initial angles of oscillation, and... 

    Effect of surface contamination on the performance of a section of a wind turbine blade

    , Article 45th AIAA Aerospace Sciences Meeting 2007, Reno, NV, 8 January 2007 through 11 January 2007 ; Volume 19 , 2007 , Pages 13026-13036 ; 1563478900 (ISBN); 9781563478901 (ISBN) Soltani, M. R ; Birjandi, A. H ; Sharif University of Technology
    2007
    Abstract
    A series of low speed wind tunnel tests on a section of a 660 Kw wind turbine blade which is under constructer were conducted to examine the effects of distributed surface contamination on its performance characteristics. At first model was tested in the clean condition and after that it was tested with tree different types of roughness. The data shows that this particular airfoil is very sensitive to the applied surface roughness. For the contaminated model the roughness, 0.5mm height was distributed over the entire upper surface of the airfoil such that the distribution pattern was denser in the vicinity of the leading edge and thinner in the trailing edge area. Statistical data show that... 

    Effects of reduced frequency on the performance of a wind turbine blade in the low and high turbulent unsteady flow

    , Article 25th AIAA Applied Aerodynamics Conference, 2007, Miami, FL, 25 June 2007 through 28 June 2007 ; Volume 2 , 2007 , Pages 877-882 ; 10485953 (ISSN); 1563478986 (ISBN); 9781563478987 (ISBN) Soltani, M. R ; Amiralaei, M. R ; Sharif University of Technology
    American Institute of Aeronautics and Astronautics Inc  2007
    Abstract
    An extensive experimental study is conducted to investigate the effects of reduced frequency on a harmonically pitching wing where its cross section is used in a 660 kW wind turbine under construction in Iran. The corresponding lift coefficient and real time pressure signatures at three sections of the model at various reduced frequencies are examined. The test covers a wide range of angles of attack at prestall, stall, and deep stall regions. Pressure distributions at tip, middle, and root sections of the wing were recorded and from these distributions the lift coefficients are computed. The results show great role of the reduced frequency in altering the maximum lift coefficients, lift... 

    Contamination effects on the performance of a wind turbine blade section

    , Article 9th AIAA/ASME Joint Thermophysics and Heat Transfer Conference Proceedings, San Francisco, CA, 5 June 2006 through 8 June 2006 ; Volume 4 , 2006 , Pages 2801-2805 ; 1563478153 (ISBN); 9781563478154 (ISBN) Soltani, M. R ; Birjandi, A. H ; Sharif University of Technology
    2006
    Abstract
    A series of low speed wind tunnel tests on a section of a 660 Kw wind turbine blade were conducted to examine the effects of distributed surface contamination on its performance. The airfoil was a section of a wind turbine blade under construction. The performance of the section was measured in the following conditions: 1. Clean airfoil 2. Two types of zigzag roughness 3. Strip tape 4. Distributed contamination roughness Our preliminary data shows that the airfoil is very sensitive to the applied surface roughness. For the contamination model the roughness, 0.5mm height, is distributed over the entire upper surface of the airfoil. By putting the contamination roughness on the airfoil the... 

    Wind turbine power improvement utilizing passive flow control with microtab

    , Article Energy ; Volume 150 , 2018 , Pages 575-582 ; 03605442 (ISSN) Ebrahimi, A ; Movahhedi, M ; Sharif University of Technology
    Elsevier Ltd  2018
    Abstract
    In this study, the effect of deploying microtabs on performance improvement of a horizontal axis wind turbine blade is numerically investigated in three-dimensions. The NREL Phase VI, a stall-regulated upwind wind turbine, is used as the baseline case. Different cases are considered to investigate the effects of spanwise location as well as the height variation of tabs along the blade span, on the flow over the rotor blade. In all cases, the tab is located at 95% chord of the airfoil section on the lower surface of the blade. Results reveal that locating microtabs at the outboard part of the blade has a greater impact on the rotor performance than the inboard part. However, both cases... 

    Unsteady Aerodynamic Simulation of Horizontal Axis Wind Turbine (HAWT)

    , M.Sc. Thesis Sharif University of Technology Radmanesh, Amirreza (Author) ; Abbaspour, Madjid (Supervisor) ; Soltani, Mohamad Reza (Co-Advisor)
    Abstract
    The ultimate aim of this research is optimizing high- performance Horizontal Axis Wind Turbine (HAWT) associated with using Computational fluid dynamics (CFD) to predict the flow behavior over wind turbine blades. Computational prediction of the flow over wind turbines is a challenging numerical problem because of the complicated aerodynamics and large variation in length scales. Phenomena such as; the unsteady flow, vortex shedding of the blade tips, flow separation, complicated blade geometry due to variable twist and chord and changes in angle of attack, and highly turbulent flow over blade sections makes CFD prediction challenging, as well as interesting. The goal is to gain an in depth... 

    RANS simulations of the stepped duct effect on the performance of ducted wind turbine

    , Article Journal of Wind Engineering and Industrial Aerodynamics ; Volume 145 , October , 2015 , Pages 270-279 ; 01676105 (ISSN) Zabihzade Roshan, S ; Alimirzazadeh, S ; Rad, M ; Sharif University of Technology
    Elsevier  2015
    Abstract
    With the rise in oil price and population growth, renewable energies are assumed to be the main source of energies for the next generation. Wind as a natural, eco-friendly and renewable source of energy has been at the center of concentration for decades. Recently there has been some ideas regarding the self-regulating urban wind turbines. Researchers have shown that a proper enclosure increases the wind velocity and therefore more torques can be exerted on the rotors, therefore more power can be generated. These enclosures are light and cheap, therefore they are applicable and effective. In the present study, an enclosure was modified to increase the exerted torque with implementing a step... 

    Experimental investigation of the leadingedge roughness on the boundary layer of a plunging airfoil

    , Article 27th Congress of the International Council of the Aeronautical Sciences 2010, ICAS 2010, 19 September 2010 through 24 September 2010, Nice ; Volume 2 , 2010 , Pages 1582-1588 ; 9781617820496 (ISBN) Rasi Marzabadi, F ; Soltani, M. R ; Masdari, M ; Sharif University of Technology
    2010
    Abstract
    Extensive experimental investigation was conducted to study the effect of leading-edge roughness on the state of the boundary layer of a wind turbine blade section. The application of surface grit roughness simulates surface irregularities that occur on the wind turbine blades. The measurements were done using multiple hot-film sensors and surface pressure transducers in both static and plunging oscillation of the airfoil. Frequency domain analysis was used to determine the state of the unsteady boundary layer  

    Statistical evaluation of using the new generation of wind turbines in South Africa

    , Article Energy Reports ; Volume 6 , November , 2020 , Pages 2816-2827 Mostafaeipour, A ; Jahangiri, M ; Haghani, A ; Hosseini Dehshiri, S. J ; Hosseini Dehshiri, S. S ; Sedaghat, A ; Saghaei, H ; Akinlabi, E. T ; Sichilalu, S. M ; Chowdhury, S ; Techato, K ; Issakhov, A
    Elsevier Ltd  2020
    Abstract
    In the view of the latest status and the potential of developing wind energy in South Africa, the present study aims to perform technical–economic–environmental analysis on a wind turbine system with HOMER software using the 20-years average data of the wind speed obtained from NASA's database, for providing the electricity to residential buildings. The results showed that the Port Elizabeth station, had the lowest levelized cost of electricity (LCOE) with the value of -0.363 $/kWh when using the EOLO wind turbine, and the Bloemfontein station had the highest LCOE with the value of 1.601 $/kWh when using the Turby wind turbine. The results from the step-wise assessment ratio analysis... 

    Nonsingular terminal sliding mode control with ultra-local model and single input interval type-2 fuzzy logic control for pitch control of wind turbines

    , Article IEEE/CAA Journal of Automatica Sinica ; Volume 8, Issue 3 , 2021 , Pages 690-700 ; 23299266 (ISSN) Abrazeh, S ; Parvaresh, A ; Mohseni, S. R ; Jahanshahi Zeitouni, M ; Gheisarnejad, M ; Khooban, M. H ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2021
    Abstract
    As wind energy is becoming one of the fastest-growing renewable energy resources, controlling large-scale wind turbines remains a challenging task due to its system model nonlinearities and high external uncertainties. The main goal of the current work is to propose an intelligent control of the wind turbine system without the need for model identification. For this purpose, a novel model-independent nonsingular terminal sliding-mode control (MINTSMC) using the basic principles of the ultra-local model (ULM) and combined with the single input interval type-2 fuzzy logic control (SIT2-FLC) is developed for non-linear wind turbine pitch angle control. In the suggested control framework, the... 

    Nonsingular terminal sliding mode control with ultra-local model and single input interval type-2 fuzzy logic control for pitch control of wind turbines

    , Article IEEE/CAA Journal of Automatica Sinica ; Volume 8, Issue 3 , 2021 , Pages 690-700 ; 23299266 (ISSN) Abrazeh, S ; Parvaresh, A ; Mohseni, S. R ; Zeitouni, M. J ; Gheisarnejad, M ; Khooban, M. H ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2021
    Abstract
    As wind energy is becoming one of the fastest-growing renewable energy resources, controlling large-scale wind turbines remains a challenging task due to its system model nonlinearities and high external uncertainties. The main goal of the current work is to propose an intelligent control of the wind turbine system without the need for model identification. For this purpose, a novel model-independent nonsingular terminal sliding-mode control (MINTSMC) using the basic principles of the ultra-local model (ULM) and combined with the single input interval type-2 fuzzy logic control (SIT2-FLC) is developed for non-linear wind turbine pitch angle control. In the suggested control framework, the... 

    Analysis of Blades Surface Effect on Wind Turbine Performance

    , M.Sc. Thesis Sharif University of Technology Sabzehparvar, Amir Ali (Author) ; Sadr Hosseini, Hani (Supervisor) ; Sabzehparvar, Mahdi (Supervisor)
    Abstract
    The development of wind turbine blades model that accurately predict wind turbine thrust in a full range of applicable wind speed has provided a powerful and reliable source for simulation of horizontal axis wind turbine power and thrust force that serves as a valuable tool for wind turbine design and performance analysis. A single-element blade model that reduces the rotor blade characteristics to a lift and drag coefficient vs. angle-of-attack formulation was found to describe accurately the rotor characteristics over a wide operating range. Measurements of wind speed and altitude of wind turbine installation location, rotor speed, and provided thrust is within less than 2% over a wide... 

    Probabilistic optimal power flow in correlated hybrid wind-PV power systems: A review and a new approach

    , Article Renewable and Sustainable Energy Reviews ; Vol. 41 , 2014 , pp. 1437-1446 ; ISSN: 13640321 Aien, M ; Rashidinejad, M ; Firuz-Abad, M. F ; Sharif University of Technology
    Abstract
    Hastening the power industry reregulation juxtaposed with the unprecedented utilization of uncertain renewable energies (REs), faces power system operation with sever uncertainties. Consequently, uncertainty assessment of system performance is an obligation. This paper reviews the probabilistic techniques used for probabilistic optimal power flow (P-OPF) studies and proposes a novel and powerful approach using the unscented transformation (UT) method. The heart of the proposed method lies in how to produce the sampling points. Appropriate sampling points are chosen to perform the P-OPF with a high degree of accuracy and less computational burden compared with features of other existing... 

    A numerical investigation on effects of the gap between plates of Savonius vertical axis wind turbines with different shapes on their performance

    , Article ASME 2012 Gas Turbine India Conference, GTINDIA 2012, 1 December 2012 through 1 December 2012 ; December , 2012 , Pages 259-264 ; 9780791845165 (ISBN) Abbaszadeh, M ; Doroodian, F ; Sharif University of Technology
    2012
    Abstract
    Present study introduces the vertical gap between the blades of a Savonius rotor's blades as a parameter that can enhance performance of the rotor. To provide comprehensive concept about application of gap between blades, two different models were tested in different working conditions and working regimes. The study completed by using R.S.M. turbulence model through ANSYS Fluent commercial software package. Utilization of the method was validated by comparing results of a conventional model with experimental data from one of the references. Results of the study proved that application of a proper gap between blades can improve rotor's moment coefficient by 20 percent; however, the amount of... 

    The influence of free stream turbulence intensity on the unsteady behavior of a wind turbine blade section

    , Article 45th AIAA Aerospace Sciences Meeting 2007, Reno, NV, 8 January 2007 through 11 January 2007 ; Volume 11 , 2007 , Pages 7611-7618 ; 1563478900 (ISBN); 9781563478901 (ISBN) Seddighi, M ; Soltani, M. R ; Sharif University of Technology
    American Institute of Aeronautics and Astronautics Inc  2007
    Abstract
    Extensive wind tunnel tests have been conducted to investigate effects of turbulence intensity variations on the behavior of a section of a wind turbine blade in an oscillatory motion. Special emphasize was applied on the aerodynamic characteristics when oscillating the model in the vicinity of its static stall angle of attack and in the post stall condition. The model had 0.25m chord and was pitched about its quarter-chord. Data were acquired at various Reynolds number, and reduced frequency. Results show that turbulent intensity has strong effect on the unsteady load coefficients, hence aerodynamic performance of this model. Furthermore, free stream turbulence has different effect on the... 

    An analytical method for the reliability evaluation of wind energy systems

    , Article TENCON 2005 - 2005 IEEE Region 10 Conference, Melbourne, 21 November 2005 through 24 November 2005 ; Volume 2007 , 2005 ; 21593442 (ISSN); 0780393112 (ISBN); 9780780393110 (ISBN) Ehsani, A ; Fotuhi, M ; Abbaspour, A ; Ranjbar, A. M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2005
    Abstract
    Wind generation is one of the most successful sources of renewable energy for the production of electrical energy. The technical characteristics of wind generation make existing conventional generation models not directly applicable. This paper presents an analytical method for the reliability assessment of the flat-rated wind turbine generation systems. An example of flat rating is that of the MOD-2, a second-generation class of wind turbines. The power-velocity characteristic of the flat-rated wind turbines is employed in this paper to model the operating behavior of the installed wind turbine generators. For wind-power potential estimation, the Weibull distribution model is used. The...