Wind farm construction is increasing progressively, to cope-up with the current global energy scenario. The advantage of clean energy and sustainability helps wind turbine construction to flourish rapidly. Location of wind turbines is independent of foundation soil condition but depends on the wind speeds and socio-environment issues. Hence, a construction sites may not be favorable in terms of geotechnical demands. The taller wind towers facilitate the generation of high energy production, which will increase loads on the foundation, and eventually increase the dimension of the foundation. Hence, the choice of a suitable foundation system is necessary for geotechnical engineer to design tall wind towers. This study aims to analyze different foundation types e.g., raft/mat foundation, pile group foundation, and piled raft/mat foundation using analytical calculation verified with numerical models using PLAXIS 3D software. The foundation for steel wind turbine towers 100 m high was designed for different types of soils e.g., soft clayey soil, medium-stiff clayey soil, stiff clayey soil, and sandy soil. The design wind speed was taken from the ASCE 7-10 (2010) standard for Occupancy Category III and IV Buildings and Other Structures, as the Illinois region falls in that category. The parametric study was performed by varying the diameter of raft/mat, wind speed, number of piles, and soil types to evaluate the settlement in any type of foundation with load sharing proportion in piled raft/mat foundation. First, the raft/mat foundation design was carried out manually by changing the diameter of 15 m, 20 m, 25 m, 30 m, and 35 m, and changing load by considering different wind speed. Then the foundation was modeled using PLAXIS 3D software with a raft/mat diameter of 25 m, 30 m, and 35 m only, by considering the eccentricity and factor of safety criteria. With the increase in wind speed, the differential settlement on the raft/mat foundation was found to be increased. However, the increase in diameter of raft/mat caused the reduction in differential settlement. Soft clayey soil was found to be more sensitive than other soils used in the present study. For the same diameter of raft/mat, applied the same wind load, the differential settlement of foundation in soft clayey soil was found to be 6-10 times higher than the sandy soil.The position of piles was fixed based on the spacing criteria in the pile group foundation. The number of piles used in this study were 23, 32, and 46. Settlement was found to be varied with the number of piles in all soils used in this study. The lateral deflection for soft clayey soil decreased to half, when number of piles increased from 23 to 46. The differential settlement was found to be increased with the increase in wind speed in pile group foundation. Raft/mat foundation settlement was found to be 4 to 6 times higher than the settlement in pile group foundation in any soils, used in this study, for a given wind speed.The result of piled raft/mat foundation showed that the majority of the total load is shared by the piles (i.e., 60% to 94%) and remaining load is shared by the raft/mat (i.e., 6% to 40%), based on the stiffness of raft/mat and piles as well as pile-soil-pile interaction. The increase in wind speed in the wind turbines increased the differential settlement of piled raft/mat foundation in all soils. Similarly, the lateral deflection also increased with the increase in wind speed in pile raft/mat foundation in all soils. The PLAXIS 3D analysis revealed that the differential settlement in soft clayey soil was 1.5 to 2.0 times higher than the settlement in sandy soil.The validation of numerical modeling was carried out by the raft/mat foundation using Boussinesq’s theory and calculating settlement for single pile and group pile foundation. The current study showed that the soft clayey soil and medium-stiff clayey soil favor deep foundation, like pile group and piled raft/mat rather than shallow foundation, like raft/mat foundation. The results obtained from both analytical calculation and numerical modeling was found to be approximately matching. This study will help local construction company and geotechnical engineer to guide a proper foundation design of tall onshore wind turbine.

Nowadays wind turbines are clustered in wind farms and the wake development plays an important role in energy production and blade fatigue load of tubines. The actuator line method is an effective modeling approach that gives improtant wake flow characterstics of a wind turbine. In the last few years, numerous studies have been conducted based on this method using Ellipsys3D, a computational fluid dynamics (CDF) flow solver based on finitie volume approach. However, due to the limited order of accuracy of this solver, it is not capable of a linear stability analysis with small amplitude of perturbation. Therefore, the present work investigates implementing the actuator line ethos into a  high order method, Nek5000, a flow solver based on the spectral element approach. The main goal of the present work is to validate the code implementation by comparing the simulations results with the previous Ellipsys3D data. Both 2-D and 3-D Gaussian distribution functions are discussed for the actuator line force distribution. Parametric study is carried out regarding the smoothing parameter ε and the partitioning of the actuator line.

This study presents a Techno-economic assessment of a renewables based power generation project for PS 21, a Pumping Station for Kenya Pipeline Company located in Nairobi, Kenya. The load for the pumping station is 1135 kW Continuous. The assessment criteria used was levelized cost of energy. The hybrid renewable energy system software HOMER was used for assessment, and modeling was done using hourly TMY data for solar irradiance and wind.  According to the results, Hybrid Solar PV-Wind- Battery renewable energy systems can supply adequate power for pumping station purposes. Optimization modeling at 2010 prices gave a levelized cost of energy of $0.2 per kWh for the most optimal solution which consisted of 2 No. 1650 kW Vestas V 82 Wind Turbines and 4070 kW of PV modules. This cost of energy just matches the purchase price from the National grid which varies between $0.14 and $0.2 per kWh, and therefore, the project is economically feasible. Mainly due to concerns of global warming, the view in the Kenyan government and society towards renewable energy is very favorable and  the project is also politically and socially feasible.   Sensitivity analysis demonstrated that wind energy is more viable than solar PV energy in areas of high wind speeds, with about 7.5 m/s annual average wind speeds.   The results show that the levelised cost of energy may be significantly decreased in future due to the fact that the cost of PV modules is progressively reducing. Payments for CERs under CDM mechanism of the Kyoto Protocol would lower the levelised cost of energy further. The Project was found to be feasible. / <p>I was a distance student and did the presentation online via centra.</p>

The Wind Turbine industry continues to drive towards high market penetrationand profitability. In order to keep Wind Turbines in field for as long as possiblecomputational analysis tools are required. The open source tool QBlade[38] softwarewas extended to now contain routines to analyse the structural properties of WindTurbine blades. This was achieved using 2D integration methods and a Tapered Euler-Bernoulli beam element in order to find the mode shapes and 2D sectional properties.This was a key step towards integrating the National Renewable Energy LaboratoriesFAST package[32] which has the ability to analyse Aeroelastic Responses. The QFEMmodule performed well for the test cases including: hollow isotropic blade, rotatingbeam and tapered beam. Some improvements can be made to the torsion estimationof the 2D sections but this has no effect on the mode shapes required for the FASTsimulations.

The workin this thesis deals with the development of anaeroelastic simulation tool for horizontal axis wind turbineapplications. Horizontal axiswind turbines can experience significanttime varying aerodynamic loads, potentially causing adverseeffects on structures, mechanical components, and powerproduction. The need of computational and experimentalprocedures for investigating aeroelastic stability and dynamicresponse have increased as wind turbines become lighter andmore flexible. A finite element model for simulation of the dynamicresponse of horizontal axis wind turbines has been developed.The simulations are performed using the commercial finiteelement software SOLVIA, which is a program developed forgeneral analyses, linear as well as non-linear, static as wellas dynamic. The aerodynamic model, used to transform the windflow field to loads on the blades, is a Blade- Element/Momentummodel. The aerodynamic code is developed by FFA (TheAeronautical Research Institute of Sweden) and is astate-of-the-art code incorporating a number of extensions tothe Blade-Element/Momentum formulation. SOSIS-W, developed byTeknikgruppen AB was used to develop wind time series formodelling different wind conditions. The model is rather general, and different configurations ofthe structural model and various type of wind conditions couldeasily be simulated. The model is primarily intended for use asa research tool when influences of specific dynamic effects areinvestigated. Simulation results for the three-bladed wind turbine Danwin180 kW are presented as a verification example. <b>Keywords:</b>aeroelastic modelling, rotor aerodynamics,structural dynamics, wind turbine, AERFORCE, SOSIS-W,SOLVIA / NR 20140805

The modern lifestyle is highly dependent on the electricity consumption, which demand is expected to continue growing worldwide, especially in those developing areas where the whole economy is transforming. Until now, most of this electricity demand had been supplied through the combustion of fossil fuels or nuclear power. But the utilization of these energy sources to power the human activity is unsustainable because of limitless of the resources and the hazardous emissions and wastes that they generate. That is why since few decades ago thewind power became one of the best-positioned renewable energy in terms of costs effectiveness as a viable alternative to the energetic model based on pollutant fossil fuels. This technology was firstly developed and implemented on those countries with a traditional environmental conscientiousness, but as the global warming issue increased new countries were interested to use wind power as a clean and sustainable energy source. The growing wind power demand of developing countries has changed in few years the entire industry, because new local manufacturers have appeared thanks to the government renewable policy, which main objective is to develop a strong domestic wind power industry capable of lead the world transformation to a clean energy model. The thesis defines the most commons renewable energy policies, and focus in the policy used in China with the aim to analyze if it is promoting or damaging the expansion of wind power use because of the priority is protect its own domestic wind power industry from international firms. The conclusions are that those protectionist policies are useful in the early stage of the industry development but the government must know the exact moment in which these subsidies and supporting mechanisms become counterproductive. If those are used during a prolonged period, then companies become dependent on subsidies and don’t act like in free markets where the innovation is the key to gain and maintain sustainable competitive advantage.

During the last decades the exploitation of energy from the wind has become one of the most promising renewable energy technologies. The main strive in today’s development of wind turbines is to increase the efficiency of the turbine and to build bigger rotors that are able to extract more power out of the wind. When it comes to the planning and designing of a wind park, also the aerodynamic interactions between the single turbines must be taken into account. The flow in the wake of the first row turbines is characterized by a significant deficit in wind velocity and by increased levels of turbulence. Consequently, the downstream turbines in a wind farm cannot extract as much power from the wind anymore. Furthermore, the additional turbulence in the wake could be a reason for increased material fatigue through flow-induced vibrations at the downstream rotor. The main focus of this experimental study is to investigate the local velocity deficit and the turbulence intensities in the wake behind an array of two model wind turbines. For two different turbine separation distances, the wake is scanned at three different downstream positions. The experiments are performed at the wind tunnel (1.9m x 2.7m cross section) at NTNU Trondheim using two model wind turbines with a rotor diameter of 0.9m. A hot wire probe is used to scan the wake behind the model turbines in defined positions. Moving axially downstream the velocity deficit in the wake gradually recovers and the turbulence intensity levels slowly decrease. Furthermore, a gentle expansion of the wake can be observed. The wake profiles measured in close distances behind the rotor are characterized by evident asymmetries. Further downstream in the wake turbulent diffusion mechanisms cause a more uniform and more symmetrical flow field. Moreover, the turbulence intensity behind the second wind turbine is found to be significantly higher than behind one unobstructed turbine. Also, considerably higher velocity deficits are found in the near wake behind the second turbine compared to the wake behind one unobstructed turbine. However, the velocity profile at five rotor diameters downstream in the wake behind the second turbine is already very similar to the velocity distribution behind the first turbine. Furthermore, the velocity field and turbulence intensity distribution in the wake behind the second turbine is more symmetrical and more uniform than behind the first turbine.

The world’s first large scale offshore wind farm, Horns Rev 1, is approaching the decommissioning phase the profitability of future investments therefore has to be investigated further. Investment decision-making requires the consideration of several perspectives based on a life cycle view of the asset’s condition and profitability. In order to contribute to the economical perspective of Asset Life Cycle Management, a business case model has been developed in two parts, one that represents the whole wind farm and one for a single wind turbine. Through the two models, the user can examine the profitability of a wind farm from a system perspective as well as on a more detailed level. The purposes of these models are to assist in the budget planning of Horns Rev 1 and provide support for investment decisionmaking.

The growing global demand for clean energy is critical, and wind power plays a crucial role in addressing this need. The increasing demand is driving advancements in the field of offshore wind power and one promising innovation is the counter-rotating vertical axis turbines (CRVT), specifically designed for floating wind power installations. The aim of this project was to develop a dynamic simulation and 3D visualization of a floating wind turbine using CRVT technology. In this project, simplified force models were created with the aim to incorporate more complex models from experts in wind and water dynamics in the future. The simplified force calculations included gravity, buoyancy, the Morison equation, as well as forces from a simple mooring and a generator. The implemented aerodynamic forces were obtained from a complex model developed by an expert in aerodynamics. The simulation was conducted in Matlab, utilizing first-principal physics for dynamics calculations. All the measurements used to compute the geometry of the wind turbine were imported from a CSV file. Finally, the RK4 method was employed to compute the steps, and a Maya model was created for the visualization of the wind turbine. In conclusion, the simulation successfully enabled the wind turbine's motion in all six degrees of freedom and provided a visual representation of the results. However, significant approximations were made, and additional validation is necessary to ensure the accuracy of the simulation.

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