Sökning: "wind turbines"

Visar resultat 21 - 25 av 183 avhandlingar innehållade orden wind turbines.

1. 21. Direct Driven Generators for Vertical Axis Wind Turbines

   Författare :Sandra Eriksson; Hans Bernhoff; Mats Leijon; Jörgen Blennow; Uppsala universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; synchronous generator; wind power; vertical axis wind turbine; simulations; experiments; finite element method; Engineering physics; Teknisk fysik;

   Sammanfattning : Wind power is a renewable energy source that is increasingly used all over the world. Most wind turbines have a horizontal axis of rotation but a few have a vertical axis of rotation. The concept presented in this thesis is a straight-bladed vertical axis wind turbine with a direct driven cable-wound permanent magnet synchronous generator. LÄS MER

3. 22. Sound propagation around off-shore wind turbines

   Författare :Lisa Johansson; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; wind turbine noise; off-shore wind powe; long-rage sound propagation; parabolic equation; scattering; water waves; Building engineering; Byggnadsteknik;

   Sammanfattning : Low-frequency, long-range sound propagation over a seasurface has been calculated using a wide-angel Cranck-NicholsonParabolic Equation method. The model is developed toinvestigate noise from off-shore wind turbines. Thecalculations are made using normal meteorological conditions ofthe Baltic Sea. LÄS MER

4. 23. Analysis, Modeling and Control of Doubly-Fed Induction Generators for Wind Turbines

   Författare :Andreas Petersson; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; current control; voltage sag; wind turbine; wind energy; doubly-fed induction generator; power quality;

   Sammanfattning : This thesis deals with the analysis, modeling, and control of the doubly-fed induction generator (DFIG) for wind turbines. Different rotor current control methods are investigated with the objective of eliminating the influence of the back electromotive force (EMF), which is that of, in control terminology, a load disturbance, on the rotor current. LÄS MER

5. 24. Fluid Mechanics of Vertical Axis Turbines : Simulations and Model Development

   Författare :Anders Goude; Olov Ågren; Carlos Simão Ferreira; Uppsala universitet; []
   Nyckelord :Wind power; Marine current power; Vertical axis turbine; Wind farm; Channel flow; Simulations; Vortex model; Streamtube model; Control system; Graphics processing unit; CUDA; Fast multipole method; Engineering Science with specialization in Science of Electricity; Teknisk fysik med inriktning mot elektricitetslära;

   Sammanfattning : Two computationally fast fluid mechanical models for vertical axis turbines are the streamtube and the vortex model. The streamtube model is the fastest, allowing three-dimensional modeling of the turbine, but lacks a proper time-dependent description of the flow through the turbine. LÄS MER

7. 25. Numerical computations of wind turbine wakes

   Författare :Stefan S. A. Ivanell; Dan Henningsson; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Applied mechanics; Wind Energy; Wind Turbine; Wake; Circulation; Vortex; CFD; EllipSys3D; Actuator line; Teknisk mekanik; Engineering mechanics; Teknisk mekanik;

   Sammanfattning : Numerical simulations using CFD methods are performed for wind turbine applications. The aim of the project is to get a better understanding of the wake behaviour, which is needed since today’s industrial design codes for wind power applications are based on the BEM (Blade Element Momentum) method. LÄS MER