Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 363 for “"Wind turbines"”.
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Maintenance optimisation for wind turbines.
Wind is becoming an increasingly important source of energy for countries that ratify to reduce the emission of greenhouse gases and mitigate the effects of global warming. Investments in wind farms are affected by inter-related assets and stakeholders requirements. These requirements demand a …
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The siting of wind turbines
… Guy Roberts completed a report on the cost of wind energy in South Africa. His results showed that wind-energy in South Africa was uneconomical, but they suggest that at locations with higher wind speeds, the cost of wind power would approach the South African grid electricity cost. Knowing …
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Condition Monitoring Techniques for Wind Turbines
… focuses on practical condition monitoring of wind turbines. With offshore wind playing an increasing part in UK electricity generation, prompt fault detection leading to preventative maintenance is gaining in importance. This work describes the development of a condition monitoring test rig …
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Advanced controls for floating wind turbines
Floating Offshore Wind Turbines (FOWT) is a technology that stands to spearhead the rapid growth of the offshore wind energy sector and allow the exploration of vast high quality wind resources over coastal and offshore areas with intermediate and large water depths. This generates the need for a …
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Flexible dynamics of floating wind turbines
… for a coupled analysis of offshore floating wind turbines consisting of a tower, a floating platform and a mooring system. In this multi-body, linear frequency-domain model, the tower is represented as a series of uniform Timoshenko beams connected to each other. The deflections of the tower …
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Parametric design of floating wind turbines
As the price of energy increases and wind turbine technology matures, it is evident that cost effective designs for floating wind turbines are needed. The next frontier for wind power is the ocean, yet development in near shore waters has been slowed by aesthetic concerns of coastal residents. …
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Wave loads on offshore wind turbines
… of alternative energy and offshore floating wind turbines are considered viable and economical means of harnessing ocean energy. The accurate prediction of nonlinear hydrodynamic wave loads and the resulting nonlinear motion and tether tension is of crucial importance in the design of …
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Air jet vortex generators for wind turbines
… is less than the air jets 'on' stall angle. A wind tunnel model was built and tested and then modified to incorporate air jets. The air jets increased CL max by 55% and reduced the drag throughout the incidence range, a, for the chosen blowing pressure of 1 p. s. i. (6900Pa). By varying the air …
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Frequency-domain modelling of floating wind turbines
The development of new types of offshore wind turbine on floating platforms requires the development of new approaches to modelling the combined platform-turbine system. In this thesis a linearised frequency-domain approach is developed which gives fast but approximate results: linearised models of …
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Below-Rated Control of Swept-Blade Wind Turbines
… studies have shown that 1.5 and 3.0 MW wind turbines with blade sweep have an increased annual energy production (AEP) of approximately 5% when compared to straight-blade wind turbines. The objective of the research was to further increase below-rated, variable speed, power capture when …
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Modeling And Control of Variable Speed Wind Turbines
Wind power is the most commonly used renewable energy source over the past decades. Among the wind turbine systems, Variable speed wind turbines are the most preferred one since it is cheaper, more efficient and has more of control capabilities over the produced active and reactive power. This …
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Innovative hull design for servicing offshore wind turbines
Accessing turbines for maintenance is a key operational issue for an offshore wind farm. Currently there is a 1.5m significant wave height (Hs) limit for the standard “step over” method of transferring personnel to an offshore wind turbine, though this varies with, vessel type, wave period and …
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Computational analysis of multielement airfoils for wind turbines
… of the inboard section of megawatt-scale wind turbine blades by increasing the lift coefficients and lift-to-drag ratios. Steady-state, two-dimensional CFD calculations were carried out for a closely-coupled three-element airfoil system with one main element and two flaps at a Reynolds …
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Dynamic response of spar-type offshore floating wind turbines
… increase in the interest in floating offshore wind turbines from the wind energy industry, governments and academia. Partially driven by the recent nuclear disaster in Japan, but also by the lack or complete absence of shallow waters in various countries around the globe (making fixed offshore …
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Experimental and theoretical study of horizontal-axis wind turbines
… and theoretical study of horizontal-axis wind turbines is undertaken. The theoretical analyses cover the four major areas of aerodynamics, turbulence. aeroelasticity and blade optimisation. EXisting aerodynamic theories based on blade-element theory for predicting the loads on a wind …
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Analytical Unsteady Aerodynamic Models for Horizontal Axis Wind Turbines
… development of unsteady aerodynamic models of wind turbines within the framework of blade element momentum theory. The main purpose is to build analytical models, and test them against available wind tunnel and field test data. The unsteady wake is modeled using vortex methods. The analysis …
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Design of wind turbines with Ultra-High Performance Concrete
… costs. However, UHPC has not been applied yet to wind turbine technology. Design codes do not propose any recommendations or guidance for the towers, thus encouraging the engineer to use less effective traditional materials like steel. The purpose of this thesis is to propose an efficient way to …
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A doubly-fed permanent magnet generator for wind turbines
Optimum extraction of energy from a wind turbine requires that turbine speed vary with wind speed. Existing solutions to produce constant-frequency electrical output under windspeed variations are undesirable due to complexity, cost, inefficiency or reliability issues. We propose a novel variation …
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Model-based fault detection and isolation techniques for wind turbines
… and isolation techniques for a large-scale wind turbine. A mathematical model of the 5MW wind turbine was developed; the model was sufficiently detailed to be used for simulation purposes. The stages of the modelling procedure were to divide the overall wind turbine system into appropriate …
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Optimized design of aerodynamic airfolis for vertical axis wind turbines
… increasing over the past years. Nowadays, wind energy represents one of the most economical options, employing a totally mature harvesting technology. Due to their higher energy output, horizontal-axis wind turbines have been traditionally the preferred option. Nevertheless, vertical-axis …
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