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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
231

Vėjo elektrinių pagaminamos elektros enrgijos prognozavimo tyrimas / Wind power stations concoction electric forecasting analysis

Pikčiūnas, Algirdas 21 June 2006 (has links)
Recently is topicality making wherewith more electrical energy from “clean” stockholding. Detractive hothouse gas exhaustion to the atmosphere. One “clean” energy is – wind power. Wind plans working in the commensurable electrical energy supply system, must “nuisance��. For this purpose essential wind electricity work forecast and respectively react to the situation. Wind power – station made electrical energy forecasting analysis I done sustaining by California experience. Forecasting is executable by wind forecast ground. Wind forecasts possible get from meteorological dimensional station or other institutions which doing wind range. Wind power – stations work essential to forecast at one hour 48 hours to the future. Such period is needful to other power – stations reaction. Wind power – stations worst worth to be built in the seaside zone or in the local pelagic there are not high flora or buildings. Wind power – stations can be built and in the others regions, but then increase the period of dividend.
232

An evaluation of wind energy potential for power generation in Mozambique.

Zucule, Jonas Nombora. January 2012 (has links)
Wind energy is a continuous, clean source of energy that can be harnessed for electricity generation or water pumping. The geographic location of Mozambique, and the long coastline renders the country a good wind energy potential that could potentially be exploited for water pumping or electrical power systems that have social and economic benefits and thereby contribute to a reduction in unsustainable practices of wood biomass burning which is the main source of energy in rural villages and high density suburbs of the main cities of the country. This study is focused on evaluating the potential of harnessing wind energy for electrical power generation in Mozambique using the Wind Atlas Analysis and Application Programme (WAsP) model. The study characterises wind speed patterns and wind frequency distributions at selected meteorological stations based on hourly observations, and models the available wind energy in coastal and interior areas. Meteorological parameters such as wind speed data from nearby meteorological stations and wind turbine characteristics were used as inputs into the model. To effectively harness wind energy, mean annual wind speeds should at least be 3 ms-1. For this reason only sites satisfying this criterion were selected. The spatial selection criteria considered a fair distribution of candidate sites such that coastal areas of the southern, northern and the interior Niassa and Nampula provinces were covered. The results of the WAsP model simulations, indicate that there is sufficient wind energy resource in both interior and coastal areas, which varies with height a.g.l., and that can be exploited for pumping water and generating electricity in small or medium electrical power systems, particularly the coastal areas of Ponta de Ouro, Mavelane, and Tofinho where the mean annual wind speed is above 5.0 ms-1 at the 10 m level and about 8.0 ms-1 at the highest levels (50 - 60 m a.g.l.) and interior area of Lichinga (mean annual wind speed of about 6 ms-1 at the same highest levels). The lowest wind energy potential (mean annual wind speed of about 4.0 ms-1) is found in the Nampula area. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2012.
233

Computational studies of horizontal axis wind turbines

Xu, Guanpeng 05 1900 (has links)
No description available.
234

The modelling of the wind profile under stable stratification at heights relevant to wind power: A comparison of models of varying complexity

Optis, Michael 23 April 2015 (has links)
The accurate modelling of the wind speed profile at altitudes relevant to wind energy (i.e. up to 200m) is important for preliminary wind resource assessments, forecasting of the wind resource, and estimating shear loads on turbine blades. Modelling of the wind profile at these altitudes is particularly challenging in stable stratification due to weak turbulence and the influence of a broad range of additional processes. Models used to simulate the wind profile range from equilibrium-based 1D analytic extrapolation models to time-evolving 3D atmospheric models. Extrapolation models are advantageous due to their low computational requirements but provide a very limited account of atmospheric physics. Conversely, 3D models are more physically comprehensive but have considerably higher computational cost and data requirements. The middle ground between these two approaches has been largely unexplored. The intent of this research is to compare the ability of a range of models of varying complexity to model the wind speed profile up to 200m under stable stratification. I focus in particular on models that are more physically robust than conventional extrapolation models but less computationally expensive than a 3D model. Observational data taken from the 213-m Cabauw meteorological tower in the Netherlands provide a basis for much of this analysis. I begin with a detailed demonstration of the limitations and breakdown in stable stratification of Monin-Obukhov similarity theory (MOST), the theoretical basis for the logarithmic wind speed profile model. I show that MOST (and its various modifications) are reasonably accurate up to 200m for stratification no stronger than weakly stable. At higher stratifications, the underlying assumptions of MOST break down and large errors in the modelled wind profiles are found. I then consider the performance of a two-layer MOST-Ekman layer model, which provides a more physically-comprehensive description of turbulence compared to MOST-based models and accounts for the Coriolis force and large-scale wind forcing (i.e. geostrophic wind). I demonstrate considerable improvements in wind profile accuracy up to 200m compared to MOST-based approaches. Next, I contrast the performance of a two-layer model with a more physically-comprehensive equilibrium-based single-column model (SCM) approach. I demonstrate several limitations of the equilibrium SCM approach - including frequent model breakdown - that limit its usefulness. I also demonstrate no clear association between the accuracy of the wind profile and the order of turbulence closure used in the SCM. Furthermore, baroclinic influences due to the land-sea temperature gradient are shown to have only modest influence on the SCM wind speed profile in stable conditions. Overall, the equilibrium SCM (when it does not break down) is found to generally outperform the two-layer model. Finally, I contrast the performance of the equilibrium SCM with a time-evolving SCM and a time-evolving 3D mesoscale model using a composite set of low-level jet (LLJ) case studies as well as a 10-year dataset at Cabauw. For the LLJ case studies, the time-evolving SCM and 3D model are found to accurately simulate the evolving stratification, the inertial oscillation, and the LLJ. The equilibrium SCM is shown to have comparatively less skill. Over the full 10-year data set, the sensitivity of the time-evolving SCM to horizontally-driven temperature changes in the ABL is found to be a considerable limitation. Despite its various limitations and simplified physics, the time-evolving SCM is generally found to be equally as accurate as the mesoscale model while using a fraction of the computational cost and requiring only a minimal amount of easily attainable local observations. Overall, the time-evolving SCM model is found to perform the best (considering both accuracy and robustness) compared to a range of equilibrium approaches as well as a time-evolving 3D model, while offering the best balance of observational data requirements, physical applicability, and computational requirements. This thesis presents a compelling case for the use of SCMs in the field of wind energy meteorology. / Graduate
235

Technical Due Diligence Assessment and Bayesian Belief Networks Methodology for Wind Power Projects

Das, Bibhash January 2013 (has links)
A Technical Due Diligence (TDD) investigation is an important step in the process of obtaining financing, or in mergers and acquisitions, for a wind power project. The investigation, the scope of which varies depending on the stage and nature of the project, involves reviewing important documentation relating to different aspects of the project, assessing potential risks in terms of the quality of the information available and suggesting mitigation or other risk management measures where required. A TDD assessment can greatly benefit from increased objectivity in terms of the reviewed aspects as it enables a sharper focus on the important risk elements and also provides a better appreciation of the investigated parameters. This master’s thesis has been an attempt to introduce more objectivity in the technical due diligence process followed at the host company. Thereafter, a points-based scoring system was devised to quantify the answered questions. The different aspects under investigation have a complex interrelationship and the resulting risks can be viewed as an outcome of a causal framework. To identify this causal framework the concept of Bayesian Belief Networks has been assessed. The resulting Bayesian Networks can be considered to provide a holistic framework for risk analysis within the TDD assessment process. The importance of accurate analysis of likelihood information for accurate analysis of Bayesian analysis has been identified. The statistical data set for the right framework needs to be generated to have the right correct setting for Bayesian analysis in the future studies. The objectiveness of the TDD process can be further enhanced by taking into consideration the capability of the investing body to handle the identified risks and also benchmarking risky aspects with industry standards or historical precedence.
236

Sustainable Energy Source for Water Pumping at Puttalam Salt Limited

Kamaldeen, Mohammed Rizwan January 2014 (has links)
The cost of grid based electrical and diesel sea water pumping to salt fields is one of the major cost components out of the total production cost in Puttalam Salt Limited, situated in northern part of Sri Lanka. In order to explore ways and means to improve the energy efficiency and alternative resources to meet the energy requirement a feasibility study was conducted using power system simulation software, (HOMER) and also detailed technical, environmental and financial tools.    This research study is conducted to evaluate the performances and applicability and propose the most suitable sustainable renewable energy source and methodology for water pumping to salt fields instead of currently utilized grid based and fossil fueled energy supply.   Preliminary results obtained by simulation software shows that direct wind mill pumping and solar PV water pumping was found to be unfeasible due to its limited pumping capacity and high investment cost. More over solar PV does not seems much feasible due to its high cost of energy (0.234 US $/kWh) compared to wind powered rivals in this type of applications.   Based on comparisons of the analysis it is seen that the wind/ grid combined configuration of 04 units of AOC15/50 model (50kW manufactured by AOC Renewable Energy - Canada) wind turbine units with 150kw inverter seems to be a logical supplement for water pumping energy requirement than using grid based electricity which costs 0.201 US $/ kWh. The solution in this research affords an attractive 60% annual average renewable fraction as well as an approximate 215.8 tCO2(eq) of annual Carbon Footprint saving. Also it assures a moderate Discounted Payback Period of 6 years and 5months with a 15% of Internal Rate of Return.
237

Wind Farm decommissioning: A perspective on regulations and cost assessment in Italy and Sweden

Giovannini, Gabriele January 2014 (has links)
Due to a lack of knowledge and experience the best approach to deal with wind farm decommissioning has yet to be determined. To fill this void, this paper analyzed the current status in terms of regulations and cost, regarding the decommissioning in Italy and Sweden.   In order to make a comparison between these two countries, the available research papers and reports on the decommissioning cost assessment, removal methods and regulations were thoroughly investigated. Moreover, detailed estimated dismantling cost data was obtained from a wind farm in Italy.   The Italian cost data were compared with data collected in Sweden and along with them, the regulations and legislations related to how these costs have to be assessed as well as what developers are required to do regarding the decommissioning in the permit issuance were included.   The results of this research show that in decommissioning cost assessment both countries does not allow developers to include the possible revenues due to the scraps and to the recycling of components, although totally different methods are pursued.   Some kind of security to ensure that decommissioning occurs is required, normally a bond. The bond amount is a debt investment in which an investor loans money to an entity (corporate or governmental) that borrows the funds for a defined period of time at a fixed interest rate. In Italy the bond requirements are generally high and it has to be paid completely for the permit issuance. In order to develop significant projects, this kind of approach leads to discourage small investors.   On the contrary, in Sweden the current amount of 300.000 SEK per turbine according to the court precedent, the most widespread during the approval of the permit, is definitely low and represent a level playing field for every investor. Swedish regulations are also more flexible and only in the 28% of the cases studied between the years 2009 and 2012, the entire amount of the bond had to be assured before the installation. However, the malleability with regard to wind farms that do not need to provide any security, together with the low bond amount might endanger the decommissioning accomplishment.
238

Characterising the uncertainty in potential large rapid changes in wind power generation

Cutler, Nicholas Jeffrey, Electrical Engineering & Telecommunications, Faculty of Engineering, UNSW January 2009 (has links)
Wind energy forecasting can facilitate wind energy integration into a power system. In particular, the management of power system security would benefit from forecast information on plausible large, rapid change in wind power generation. Numerical Weather Prediction (NWP) systems are presently the best available tools for wind energy forecasting for projection times between 3 and 48 hours. In this thesis, the types of weather phenomena that cause large, rapid changes in wind power in southeast Australia are classified using observations from three wind farms. The results show that the majority of events are due to horizontal propagation of spatial weather features. A study of NWP systems reveals that they are generally good at forecasting the broad large-scale weather phenomena but may misplace their location relative to the physical world. Errors may result from developing single time-series forecasts from a single NWP grid point, or from a single interpolation of proximate grid points. This thesis presents a new approach that displays NWP wind forecast information from a field of multiple grid points around the wind farm location. Displaying the NWP wind speeds at the multiple grid points directly would potentially be misleading as they each reflect the estimated local surface roughness and terrain at a particular grid point. Thus, a methodology was developed to convert the NWP wind speeds at the multiple grid points to values that reflect surface conditions at the wind farm site. The conversion method is evaluated with encouraging results by visual inspection and by comparing with an NWP ensemble. The multiple grid point information can also be used to improve downscaling results by filtering out data where there is a large chance of a discrepancy between an NWP time-series forecast and observations. The converted wind speeds at multiple grid points can be downscaled to site-equivalent wind speeds and transformed to wind farm power assuming unconstrained wind farm operation at one or more wind farm sites. This provides a visual decision support tool that can help a forecast user assess the possibility of large, rapid changes in wind power from one or more wind farms.
239

Development of an electrical generation scheme using wind energy

Nayar, C. V. January 1985 (has links)
[Truncated Abstract] This thesis describes investigations carried out in the development of a wind powered generation system suitable for interconnection with a power grid ... The simplicity and flexibility exhibited by the induction machines in providing electromechanical energy conversion make it the most favoured choice for wind-powered systems operated in parallel with an existing powers system. Although not as common as the ‘squirrel cage’ induction machine, the slip-ring type has several attractive features in providing constant-frequency ac power when driven from a varaible-speed source such as a wind turbine. The fundamental energy conversion properties of the induction machine system are studied in order to determine the suitability of these systems for constant-frequency variable-speed electric power generation. Two distinct control policies are formulated: (i) optimising power from the wind when the generator is connected to an ‘infinite’ bus bar and, (ii), scheduling a constant output power irrespective of fluctuations in wind speed when the generator is operated in parallel with a ‘weak grid’.
240

Dynamics of tethering cables for a flying electric generator /

Murthy, Raghuram Ananda. January 2000 (has links)
Thesis (M.Sc. (Hons)) -- University of Western Sydney, 2000. / "Thesis submitted to the University of Western Sydney, Nepean for the degree of Master of Engineering (Hons)" "School of Mechatronics, Computer and Electrical Engineering, December 2000" Includes bibliographical references (leaves 111-113).

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