As the demand for safe and clean electricity increases, the New Zealand wind energy industry seems poised to expand. Many generating companies have projects in the planning stage and there are likely to be many more potential sites yet to be identified. Reliable wind climate predictions over a wide area and for different heights above grounds are often vital to determine the viability of wind farm projects. This study investigates the use of meteorological mesoscale models to determine the wind and energy resource, particularly in areas of complex terrain. Complex terrain environments are likely to be typical of where New Zealand wind energy developments will take place. Using the prognostic mesoscale meteorological model TAPM (The Air Pollution Model), regions of relatively high mean wind speed were identified for a number of regions, including Banks Peninsula and parts of Canterbury and Otago. The simulations were conducted for a one-year period (2001) and at different heights above ground level. Depending on the resolution of the model calculations, speed-up effects from the forcing of some topographic features were accounted for by this model. Where the modelling was considered reliable, hourly wind data were obtained from grid points within the inner grid and used as input data for the industry-standard wind energy assessment model WAsP (The Wind Atlas Analysis and Application Program). As WAsP is able to account for detailed topography and surface roughness features, wind and energy predictions at a specific site or over a wider area surrounding the site were made. Limitations of both models in complex terrain were identified. These limitations were due to a number of factors, including the grid spacing used for mesoscale model calculations, the complexity of the terrain, and difficulties in modelling some regional scale airflow regimes. Being aware of when and where model limitations are likely to occur is important in being able to overcome and account for them.

This thesis assessed the use of radar as a remote technique for monitoring seabirds in offshore locations.  The study site was in the Moray Firth, Scotland, at the Beatrice oil field, where two 5 MW wind turbines were installed in the summers of 2006 and 2007.  An S-band marine surveillance radar, equipped with commercially available automatic detection and tracking software was installed on the Beatrice Alpha platform to collect ornithological data.  Significant amounts of radar clutter were also recorded in this offshore environment, so bespoke filters were developed, to remove non-avian tracks from the dataset.  Filtered data showed temporal patterns in avian activity at the site, which could be linked to existing knowledge of the use of the site by seabirds.  Flight directions during the breeding season indicated that birds using the site were also attending colonies at the East Caithness cliffs SPA to the north west.  The flight speed parameter included in models of collision between birds and wind turbines was evaluated empirically using radar data.  Ground speed, which is influenced by wind was  highly variable, and was on average 0.707 ms^-1 slower than airspeed, increasing the collisions risk relative to the model’s predictions for many birds. Boat-based visual surveys were used to investigate the impact of turbine installation on the abundance and distribution of birds at the site during the breeding season.  No effect of turbine installation was detected, but environmental variation was shown to have a significant impact on bird abundance.  This demonstrates the difficulty of designing impact studies that can detect the faint signal of an impact, against background variability inherent in marine environments.

From daily analyses of the prevailing wind at the mesopause region (about 95 km) oscillations in the period range of the so-called quasi 16-day wave are obtained that can be interpreted as the signal of these planetary waves in the wind field. Investigating these waves for the period of 1980 through 1997 in connection with the prevailing wind gives insight to the behaviour of planetary wave-mean flow interaction in the upper middle atmosphere. lt is found that in winter the planetary wave activity in the mesopause region is positively correlated with the zonal mean westerly wind, and negatively correlated with its mean vertical gradient. This means that strong planetary wave activity in the mesopause region is not necessarily connected wiht strong wave activity in the lower atmosphere, but rather is the result of incomplete wave breaking below the measuring level. / Aus täglichen Analysen des mittleren Winds im Mesopausenbereich (etwa 95 km Höhe) werden Oszillation im Periodenbereich der sogenannten quasi 16-Tage-Welle bestimmt, die als Signal dieser Welle angesehen werden. Es wird der Zusammenhang dieser Oszillationen mit dem mittleren Wind untersucht. Es zeigt sich, daß starke Wellenaktivität mit größerem (negativen) Gradienten, aber auch mit größerer mittlerer Windgeschwindigkeit verbunden ist. Dies bedeutet, daß die Variabilität der Aktivität planetarer Wellen im Mesopausenbereich nicht notwendigerweise diejeniger planetarer Wellen in der unteren Atmosphäre widerspiegelt, sondern ein Maß dafür ist, inwieweit die Energieübertragung der Wellen auf den Grundstrom im Mesopausenbereich bereits abgeschlossen ist.

Collm mesopause winds are analysed with respect to their correlation with 30 hPa northern hemispheric stratospheric winds and pressure level heights. Correlation maps, based on the period of December 1978 through November 1997, are presented for each month of the year, showing possible connections between the lower and upper middle atmosphere, partly owing to the 10-12-year oscillation (TTO). Although in winter due to the propagation of planetary waves into the mesosphere direct coupling between the different layers of the atmosphere especially during stratospheric warmings is possible, the strongest correlation between stratosphere and mesopause region is found in summer, which is for the most part connected with the solar cycle dependence of the middle atmosphere. / Die Mesopausenwinddaten vom Collm werden in Bezug auf ihre Verbindung mit stratosphärischen Winden und Druckhöhen in 30 hPa untersucht. Abbildungen der Korrelationskoeffizienten, basierend auf dem Zeitraum von Dezember 1978 bis November 1997 zeigen mögliche Verbindungen zwischen Stratosphäre und Mesopausenregion, zum Teil über die 10-12-jährige Schwingung (TTO) der Stratosphäre. Obwohl im Winter wegen der Ausbreitung planetarer Wellen in die Mesosphäre speziell während rascher Stratosphärenerwärmungen eine direkte Verbindung zwischen den Schichten der Atmosphäre auftritt, werden die stärksten Korrelationen im Sommer gefunden, größtenteils durch den Einfluß der TTO.

In the year 2002 the Swedish Energy Agency assigned the department of Earth science at Uppsala University a research assignment to make a detailed wind climatology mapping covering Sweden. A survey of the Swedish wind climate has been made earlier in some areas, using the Danish model WASP. In this study the MIUU-model is usedwhich is a mesoscale three dimensional numerical model with a turbulence closure scheme of level 2.5. The MIUU-model is computer time demanding. Therefore a method to minimize the total number of simulations is wanted, without negative effects on the result. In this thesis the main issue is to compare the sensitivities and differences between climatological wind calculations using runs with different forcing parameters, i.e. with different meteorological conditions. Primarily the climatological results received with different geostrophic wind forcing are studied and compared. The idea is to find combinations with as small deviations as possible. The parameters investigated, called flow forcing parameters, are; geostrophic wind (magnitude and direction), thermal wind and thermal stratification. To compare the calculations a reference run is used. In theruns studying the influence of the geostrophic wind, calculations where made with 1, 2, 3 and 6 geostrophic wind speeds and with 4, 8, 16 and 32 wind directions. All compared to the reference that is based on 3 wind speeds and 8 wind directions. The model has earlier been used without any thermal wind influence. Therefore radio sonde data have been used to calculate the geostrophic mean wind profile introduced in the model to make new runs. The thermal stratification has also been modified in April and October to find out the sensitivities in the model. The result shows that there are only a few possible shortcuts in the number of runs needed and in the verification of the parameters. The question is if it is worth searching for them, since they might not be valid in other areas with more complex terrain. To be on the safe side, runs like the reference runs should at least be used in order to get accurate results as regards the wind climate. / År 2002 gav Statens Energimyndighet ett uppdrag till Institutionen för geovetenskaper vid Uppsala Universitet att kartlägga det svenska vindklimatet. En kartläggning av vindklimatet i vissa delar av Sverige har gjorts tidigare med hjälp av den danska modellen WASP. I denna avhandling används MIUU-modellen som är en mesoskalig tredimensionell numerisk modell med ett ’closure scheme of level 2.5’. MIUU-modellen kräver mycket datorkraft och därför söks ett sätt att minimera antalet modellkörningar utan försämrat värde på resultaten. I denna avhandling är huvuduppgiften att jämföra känsligheten och skillnaderna mellan klimatologiska beräkningar från modellkörningar med olika drivande parametrar i modellerna, d v s med olika meteorologiska förhållanden. De erhållna klimatologiska resultaten från olika geostrofiska vindhastigheter är plottade. För att jämföra resultaten ritas en ny plott som visar avvikelserna mellan de två originalresultaten. Syftet är att hitta plottar med så små skillnader som möjligt. De undersökta parametrarna, som är av stor betydelse för modellen är: geostrofisk vind (styrka och riktning), termisk vind och temperaturskiktning. För att jämföra beräkningarna används en referenskörning. I modellkörningarna med den geostrofiska vinden görs beräkningar med 1, 2, 3 och 6 olika geostrofiska vindstyrkor och med 4, 8, 16 och 32 vindriktningar. Alla jämförs med referensen som är beräknad på 3 vindstyrkor och 8 vindriktningar. Modellen har tidigare använts utan termisk vind. Från Universitetet i Wyoming har därför data hämtats för att beräkna den geostrofiska medelvindprofilen som införts i modellen för nya modellberäkningar. Temperaturskiktningen har också modifierats i april och oktober för att kontrollera känsligheten i modellen. Resultaten visar att det bara finns några få genvägar bland parametrarna. Frågan är om det är värt att leta efter dem, eftersom de mest troligt inte är de samma om man tittar på andra områden med mer kuperad terräng. För att vara på den säkra sidan är beräkningarna med samma parametrar som referenskörningarna det bästa sättet att få bra resultat avseende vindklimatet.

Digitized by Kansas Correctional Industries

This thesis presents and examines the concept that the output of a wound-rotor induction generator (WRIG) can be limited by means of linking to external impedances for wind-turbine generating system application. An 80kW-WRIG is simulated as a model to examine the control of the output power vs. speed characteristic. Model of WRIG derived from per phase equivalent circuit is organized, then it is estimated how much external impedances affect the characteristic of output power for it to approach to a typical wind-turbine curve. Practical tests are performed using 80kW-WRIG in testing lab to validate the simulation data. In addition, a smaller WRIG, connected on same shaft as 80kW-WRIG, is designed to extend the range of wind speed. Also external impedances with smaller WRIG are chosen to extract optimum power from wind-turbine. Finally, passively controlled tandem WRIGs are shown to have the capability to optimize wind-turbine energy extraction when controlled entirely by external impedances. / Graduation date: 2003

The purpose of this work is to develop a maximum power tracking control strategy for variable speed wind turbine systems. Modern wind turbine control systems are slow, and they depend on the design parameters of the turbine and use wind and/or rotor speed measurements as control variable inputs. The dependence on the accuracy of the measurement devices makes the controller less reliable. The proposed control scheme is based on the stiff system concept and provides a fast response and a dynamic solution to the complicated aerodynamic system. This control scheme provides a response to the wind changes without the knowledge of wind speed and turbine parameters. The system consists of a permanent magnet synchronous machine (PMSM), a passive rectifier, a dc/dc boost converter, a current controlled voltage source inverter, and a microcontroller that commands the dc/dc converter to control the generator for maximum power extraction. The microcontroller will also be able to control the current output of the three-phase inverter. In this work, the aerodynamic characteristics of wind turbines and the power conversion system topology are explained. The maximum power tracking control algorithm with a variable step estimator is introduced and the modeling and simulation of the wind turbine generator system using the MATLAB/SIMULINK® software is presented and its results show, at least in principle, that the maximum power tracking algorithm developed is suitable for wind turbine generation systems.

The purpose of this work is to develop a maximum power tracking control strategy for variable speed wind turbine systems. Modern wind turbine control systems are slow, and they depend on the design parameters of the turbine and use wind and/or rotor speed measurements as control variable inputs. The dependence on the accuracy of the measurement devices makes the controller less reliable. The proposed control scheme is based on the stiff system concept and provides a fast response and a dynamic solution to the complicated aerodynamic system. This control scheme provides a response to the wind changes without the knowledge of wind speed and turbine parameters. The system consists of a permanent magnet synchronous machine (PMSM), a passive rectifier, a dc/dc boost converter, a current controlled voltage source inverter, and a microcontroller that commands the dc/dc converter to control the generator for maximum power extraction. The microcontroller will also be able to control the current output of the three-phase inverter. In this work, the aerodynamic characteristics of wind turbines and the power conversion system topology are explained. The maximum power tracking control algorithm with a variable step estimator is introduced and the modeling and simulation of the wind turbine generator system using the MATLAB/SIMULINK® software is presented and its results show, at least in principle, that the maximum power tracking algorithm developed is suitable for wind turbine generation systems.

A wind resource assessment of two sites in the Waterloo region, WRESTRC and RIM Park, was conducted using wind speed, wind direction, temperature and pressure data collected from meteorological towers for over two years. The study was undertaken as part of the W3 Wind Energy Project, and the equipment was purchased from NRG Systems and R. M. Young Company. The data was filtered to reduce the effect of icing and tower shadow, and was analyzed using MATLAB software. Based on the mean wind speeds, small wind turbines less than 50 kW in capacity would be appropriate at both sites. Wind speeds tended to be stronger during the winter than the summer, and during the afternoon than the rest of the day. Both sites also exhibited a strong dominant wind direction -- from the northwest. Due to the terrain, the wind shear and turbulence intensity at WRESTRC were moderate when the wind flowed from the dominant direction, but very high from other directions. The wind shear and turbulence intensity at RIM Park were consistently moderate in all directions. Although the terrain seems more complex at WRESTRC, the wind speed distribution and estimated annual energy production were higher at WRESTRC than at RIM Park, which indicates that it is a more viable site. The estimated capacity factors ranged from 9.4% to 22% depending on the hub height, which is not nearly high enough to suggest a commercial wind farm would be viable at either site. A small 5 kW to 15 kW wind turbine in the Waterloo region could offset the electricity usage of an average home. A two-parameter power law model of wind shear was explored and compared with the standard one-parameter model. In terms of goodness-of-fit, the two-parameter model did perform better. But in terms of accuracy of extrapolation, it was not conclusively better or worse than a one-parameter model forced through the known data point closest to the prediction height. The relationship between turbulence intensity and measurement interval was examined. Since atmospheric flow is unsteady, they are not independent. The perceived turbulence intensity was found to increase exponentially with time intervals under 24 hours. Two linear regression-based Measure-Correlate-Predict methods were evaluated using long-term data from a weather station also at WRESTRC. The ordinary least squares method was considered the baseline given its simplicity. The variance ratio method improved upon it by ensuring that the variance of the wind speed distribution at the target site was preserved.