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The generation of electricity using wind turbines is now widespread and commercially viable. There are two aspects of wind energy which are critically important. Firstly, the evaluation of the wind resource, both on nationally and on a local scale. Secondly, the integration of electricity generated by wind turbines into existing electricity grids without reducing the reliability of supply or reducing the overall economic efficiency of the system. This thesis examines both these aspects. Chapters 3 and 4 are concerned with the large scale utilisation of wind energy. Chapter 3 discusses the suitability for wind energy evaluation of the data held by the UK Meteorological office, describes the results of a detailed examination of over 130 station-years of hourly data, and recommends areas of further study as well as a UK standard for site description. Chapter 4 describes a computer model used to examine the effects of integrating wind-generated electricity into the CEGB National Grid and the results obtained with it. The relative importance of dispersal of wind turbines, load and wind forecasting, variation of turbine characteristics and inter-annual variability of wind speed is determined. Chapters 5 and 6 are concerned with a detailed evaluation of thewind energy potential on the Shetland island group. Chapter 5 describes the planning, testing and installation of two hill-top monitoring stations on Shetland and the results found. Chapter 6 describes the development of a computer model of the Shetland Power Station, which is used to examine how the introduction of wind turbines would affect the operation of the power station and the maximum energy penetration possible before power cuts occur. Both chapters conclude with detailed recommendations which will be of worldwide use as the wind energy potential of other diesel-fuelled grids is determined.

The configuration of a wind turbine and its control system dictate the dynamics of the machine. Since the dynamics of each part of the wind turbine affect those of the others, the machine should be considered as an integrated unit. The objective of the research reported here is to lay the foundations for the control aspects of integrated design by determining the dependence of the power controller performance of medium- and largescale, actively regulated, up-wind, horizontal-axis, grid-connected wind turbines on their configuration, that is, the dependence of the magnitude of the loads experienced by the drive train on the machine characteristics. There is a tendency amongst manufacturers to move from conventional, heavy and stiff machines to ones with lighter and more flexible components which makes machines more dynamically active and hence makes the power control task more difficult. Simple thoroughly derived linear and non-linear models of the significant wind turbine dynamics for power control are used to obtain a greater understanding of how machine parameters effect the overall behaviour of the power train. The dependence of the power controller performance of different full-span and tip-regulated machines is discussed. Finally, explanation of the results is illustrated with regard to the design of a 1 MW wind turbine.

The Weather Channel (TWC) and AccuWeather (AWX) are leading providers of weather information to the general public. The purpose of this Master’s Report is to examine the wind speed forecasts made by these two providers and determine their reliability and accuracy. The data used within this report was collected over a 12-month period at 51 locations across the state of Texas. The locations were grouped according to wind power class, which ranged from Class 1 to Class 4. The length of the forecast period was 9 days for TWC and 14 days for AWX. It was found that the values forecasted by TWC were generally not well calibrated, but were never far from being perfectly calibrated and always demonstrated positive skill. The sharpness of TWC’s forecasts decreased consistently with lead time, allowing them to maintain a skill score greater than the climatological average throughout the forecast period. TWC tended to over-forecast wind speed in short term forecasts, especially within the lower wind power class regions. AWX forecasts were found to have positive skill the first 6 days of the forecasting period before becoming near zero or negative. AWX’s forecasts maintained a fairly high sharpness throughout the forecast period, which helped contribute to increasingly un-calibrated forecast values and negative skill in longer term forecasts. The findings within this report should help provide a better understanding of the wind forecasts made by TWC and AWX, and determine the strengths and weaknesses of both companies. / text

published_or_final_version / abstract / toc / Civil Engineering / Master / Master of Philosophy

published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

The purpose of this research was to demonstrate the viability of a method, due to Professor W. R. Sears, for obtaining wind-tunnel wall-corrections from measurements of near-field flow parameters by an interative procedure. A case is made for the improved accuracy of this method over the standard method of images. The wall-correction method was applied to an actual wind-tunnel test of a slightly oversized wing model at low subsonic speeds (Mach number ≈ 0.1). The wind tunnel facility and experimental setup and method are described and discussed. The wall-correction method consists of iterating between the region of space exterior to the test section boundary and the one interior to it. The flow fields in both regions are defined in terms of plane singularity elements each with an unknown, constant strength distribution. The method for expressing these flow fields as a linear system and for obtaining the associated matrices is described. The boundary conditions for the inner flow are slightly different from those of the outer flow because of the presence of the wing. There are actually two different but consistent sets of boundary conditions at the wing which lead to two different but compatible calculations for the wall-correction. The near-field flow parameter measured during the wind-tunnel test is the wing perturbation velocity potential, obtained from the quantity p ͚ - pᵢ. Here, i represents any of the 46 static taps distributed over the test section walls. It was decided to use 140 singularity elements for the outer flow description; therefore, a method was devised for fitting a least-squares surface to the measured p̂ᵢ's and integrating to obtain 140φᵢ's. The procedure for the iterations is described and the criterion for convergence to unconfined flow is presented. Test cases consisting of known, simple flows are used along the way to verify the computational methods. Finally, the wall correction to the lift curve of the wing model is presented as well as the correction at a typical tail position and the correction to the induced drag of the wing.

No description available.

Power generation using wind turbines is a highly researched control field. Many control designs have been proposed based on continuous-time models like PI-control, or state observers with state feedback but without special regard to robustness to model uncertainties. The aim of this thesis was to design a robust digital controller for a wind turbine. The design was based on a discrete-time model in the polynomial framework that was derived from a continuous-time state-space model based on data from a real plant. A digital controller was then designed by interactive pole placement to satisfy bounds on sensitivity functions. As a result the controller eliminates steady state errors after a step response, gives sufficient damping by using dynamical feedback, tolerates changes in the dynamics to account for non linear effects, and avoids feedback of high frequency un modeled dynamics.