Search for: wind-turbine
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    Experimental study of the plunging motion with unsteady wind tunnel wall interference effects

    , Article Experimental Techniques ; Volume 36, Issue 5 , FEB , 2012 , Pages 30-45 ; 07328818 (ISSN) Soltani, M. R ; Marzabadi, F. R ; Mohammadi, Z ; Sharif University of Technology
    A series of experiments were carried out to investigate unsteady behavior of the flow field as well as the boundary layer of an airfoil oscillating in plunging-type motion in a subsonic wind tunnel. The measurements involved surface-mounted hot films complimented with surface pressure. In addition, wind tunnel wall pressure distribution was acquired to furnish a baseline for the wall interference corrections. The airfoil is the section of a 660-kW wind turbine blade. The experiments were conducted at a Reynolds number of 0.42 million, and over two reduced frequencies of k = 0.06 and 0.085, at prestall, nearstall, and poststall regions. The unsteady aerodynamic loads were calculated from the... 

    Stand alone performance of permanent magnet synchronous wind power generator with current source matrix converter

    , Article Electric Power Components and Systems ; Volume 43, Issue 8-10 , 2015 , Pages 1018-1027 ; 15325008 (ISSN) Hojabri, H ; Mokhtari, H ; Chang, L ; Sharif University of Technology
    Taylor and Francis Inc  2015
    A matrix converter is a voltage/current source AC/AC frequency converter. In grid-connected operation of a variable-speed permanent magnet synchronous wind power generator, the matrix converter is normally controlled as a voltage source converter. In this control method, the generator-side voltage is synthesized from the grid-side voltage source. However, in the stand-alone mode of operation, the grid-side stiff voltage source is not available, and the input filter of the matrix converter is unstable. In this article, a new control method is presented that controls a permanent magnet synchronous wind generator in a stand-alone mode with a matrix converter as a current source converter. The... 

    Dynamic behavior analysis of doubly-fed induction generator wind turbines - The influence of rotor and speed controller parameters

    , Article International Journal of Electrical Power and Energy Systems ; Volume 32, Issue 5 , June , 2010 , Pages 464-477 ; 01420615 (ISSN) Rahimi, M ; Parniani, M ; Sharif University of Technology
    This paper analytically investigates the effects of system and controller parameters and operating conditions on the dynamic and transient behavior of wind turbines (WTs) with doubly-fed induction generators (DFIGs) under voltage dips and wind speed fluctuations. Also, it deals with the design considerations regarding rotor and speed controllers. The poorly damped electrical and mechanical modes of the system are identified, and the effects of system parameters, and speed/rotor controllers on these modes are investigated by modal and sensitivity analyses. The results of theoretical studies are verified by time domain simulations. It is found that the dynamic behavior of the DFIG-based WT... 

    Modification of DFIG's active power control loop for speed control enhancement and inertial frequency response

    , Article IEEE Transactions on Sustainable Energy ; Volume 8, Issue 4 , 2017 , Pages 1772-1782 ; 19493029 (ISSN) Ashouri Zadeh, A ; Toulabi, M ; Bahrami, S ; Ranjbar, A. M ; Sharif University of Technology
    This paper proposes a fuzzy-based speed controller for the doubly fed induction generator (DFIG)-based wind turbines with the rotor speed and wind speed inputs. The controller parameters are optimized using the particle swarm optimization algorithm. To accelerate tracking the maximum power point trajectory, the conventional controller is augmented with a feed-forward compensator, which uses the wind speed input and includes a high-pass filter. The proposed combined speed controller is robust against wind measurement errors and as the accuracy of anemometers increases the speed regulation tends toward the ideal controller. The cutoff frequency of the applied filter is determined considering a... 

    Parallelized numerical modeling of the interaction of a solid object with immiscible incompressible two-phase fluid flow

    , Article Engineering Computations (Swansea, Wales) ; Volume 34, Issue 3 , 2017 , Pages 709-724 ; 02644401 (ISSN) Ghasemi, A ; Nikbakhti, R ; Ghasemi, A ; Hedayati, F ; Malvandi, A ; Sharif University of Technology
    Purpose - A numerical method is developed to capture the interaction of solid object with two-phase flow with high density ratios. The current computational tool would be the first step of accurate modeling of wave energy converters in which the immense energy of the ocean can be extracted at low cost. Design/methodology/approach - The full two-dimensional Navier-Stokes equations are discretized on a regular structured grid, and the two-step projection method along with multi-processing (OpenMP) is used to efficiently solve the flow equations. The level set and the immersed boundary methods are used to capture the free surface of a fluid and a solid object, respectively. The full... 

    Impact of innovation programs on development of energy system: case of Iranian electricity-supply system

    , Article Energy Policy ; Volume 37, Issue 6 , 2009 , Pages 2221-2230 ; 03014215 (ISSN) Shafiei, E ; Saboohi, Y ; Ghofrani, M. B ; Sharif University of Technology
    The paper presents further experiments with an extended version of a comprehensive model for assessment of energy technologies and research and development (R&D) planning to evaluate the impact of innovation programs on development of Iranian electricity-supply system. This analytical instrument is a model of energy R&D resource allocation with an explicit perspective of developing countries which has been linked to a bottom-up energy-systems model. Three emerging electricity generation technologies of solar PV, wind turbine and gas fuel cell are considered in the model and the impact of innovation programs on cost-reducing innovation for them is examined. The main results provided by the...