Universität Stuttgart
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Item Open Access Untersuchung der Antriebsstrangdynamik in Windenergieanlagen(2020) Horch, JoachimDiese Arbeit beschäftigt sich damit die Stabilität und Funktionstüchtigkeit des Antriebsstranges einer Windenergieanlage der Größenordnung 10 MW zu untersuchen. Hierfür erfolgt der Aufbau eines Computermodells einer 10-MW-Windenergieanlage mithilfe des Mehrkörpersimulationsprogrammes SIMPACK. Weiterhin wird eine Parameterstudie durchgeführt, welche über eine Matlab-induzierte SIMPACK-Simulation speziell ausgewählte Parameter des Antriebsstranges variiert, Simulationen durchführt und so den Einfluss bestimmter Parameter, sowie Parameterkombinationen, auf die Stabilität des Antriebsstranges prüft. Auf diese Weise sollen Stabilitätskriterien für einen Antriebsstrang dieser Größenordnung ermittelt werden. Es erfolgen sowohl statische, als auch dynamische Untersuchungen.Item Open Access Experimental investigation of low-frequency sound and infrasound induced by onshore wind turbines(2024) Blumendeller, Esther; Cheng, Po Wen (Prof. Dr.)Climate change has a global impact and is increasingly affecting our environment. This is driving the continuous expansion of renewable energies, with wind energy playing a major role. As wind energy becomes more widespread, an increasing number of people will live near wind turbines in complex terrain. In such scenarios, wind turbines are often positioned at elevated locations, while residents live in valleys. In complex terrain, such as a steep escarpment, local turbulence, wind speed, and direction are strongly influenced by topography, contributing to the complexity of sound propagation or impacts the background noise situation in valleys, for example, due to shielding effects. The operation of wind turbines is associated with both visual and sound-related impact, with sound being generated at various frequencies. There is a growing interest in low-frequency sound and infrasound, characterized by long wavelengths that propagate over considerable distances without significant attenuation. This is in contrast to higher-frequency sound, and might increase the impact of wind turbine sound at residential areas located several hundred meters or a few kilometers away from the wind farm. In the context of complex terrain, this work investigates wind turbines in complex terrain as sources of low-frequency sound and infrasound. The investigations on characterization of sound generation and propagation are based on measurements in the vicinity of two wind farms. Measurements were conducted within four measurement campaigns at two wind farms located close to an escarpment at the Swabian Alb in Southern Germany over a period of about nine month. Acoustic data was obtained in the proximity of the wind turbines and at residential buildings in 1–1.7km distance to the wind farms in municipalities located within a valley. Besides acoustic measurements including the infrasonic frequency range, a comprehensive data set with ground motion data, wind turbine operating data, meteorological data and data from a noise reporting app supports the investigation. Two aspects require analysis: Firstly, the aspect of generation and propagation of wind turbine low-frequency sound and infrasound in complex terrain, and secondly, the relation with annoyance. Results show that sounds within the infrasonic range assigned to the blade passage at the tower are transmitted through the air over distances of 1 km. Low-frequency sounds were found to be amplitude-modulated and were investigated as amplitude modulation. Infrasound and amplitude modulation occurrences were more likely during morning, evening and night hours and during atmospheric conditions with positive lapse rate, vertical wind shear and low turbulence intensity. The occurrence of both infrasound and amplitude modulation was typically observed during rated rotational speed but below-rated power. To allow predictions, a standard prediction method was extended to include the lowfrequency sound and infrasound range and adapted to the measurement data in order to apply it to complex terrain. The sound level difference of the measured data aligns well with the predictions within the frequency range of 8 Hz and 250 Hz. Investigations regarding outdoor-to-indoor sound reductions showed influences from structural resonances and room modes, which depend on the characteristics of the building and the specific room under investigation. Combining acoustic measurements with annoyance reports showed that rated wind turbine operation appears to be a contributing factor in annoyance ratings obtained through a noise reporting app, ranging from “somewhat” to “very” levels. Furthermore, the analysis indicates that varying levels of annoyance at a distance of 1km from the wind farm, both outside and inside buildings, do not correspond to significant differences in the averaged and A-weighted sound pressure levels. Overall, this work contributes to a better understanding of the low-frequency sound and infrasound generated from wind turbines and provides insight into the sound characteristics of measured wind turbine sound at residential locations in complex terrains.Item Open Access Comparison of feedforward and model predictive control of wind turbines using LIDAR(2012) Schlipf, David; Pao, Lucy Y.; Cheng, Po WenLIDAR systems are able to provide preview information of wind disturbances at various distances in front of wind turbines. This technology paves the way for new control concepts such as feedforward control and model predictive control. This paper compares a nonlinear model predictive controller and a feedforward controller to a baseline controller. Realistic wind "measurements" are obtained using a detailed simulation of a LIDAR system. A full lifetime comparison shows the advantages of using the wind predictions to reduce wind turbine fatigue loads on the tower and blades as well as to limit the blade pitch rates. The results illustrate that the feedforward controller can be combined with a tower feedback controller to yield similar load reductions as the model predictive controller.Item Open Access Messungen im Bereich eines Windparks mit Fokus auf tief- und niederfrequente Schallemissionen und -immissionen(2022) Blumendeller, Esther; Gaßner, Laura; Müller, Florian; Wigger, Maayen; Berlinger, Philipp; Cheng, Po WenDie Nutzung von Windenergie wird einen entscheidenden Anteil am erneuerbaren Energiemix der Zukunft haben. Während der Stromgewinnung geben Windenergieanlagen (WEA) Schall und Erschütterungen (seismische Wellen) in die Umgebung ab, vor allem im tieffrequenten Bereich. Im Zuge des interdisziplinären Verbundprojektes Inter-Wind werden akustische Messungen zur Unterstützung psychologischer Fragebögen, kombiniert mit seismischen und meteorologischen Messungen an Windparks auf der Schwäbischen Alb durchgeführt. Ziel des Projektes ist es, die Gründe für Belästigung der Anwohner in Zusammenhang mit den Immissionen der WEA zu verstehen. Hierbei liegt der Fokus auf dem tieffrequenten (20-200 Hz) und niederfrequenten (1-20 Hz) Bereich. Akustische und seismische Messungen wurden an einem Windpark auf der Schwäbischen Alb, mit drei WEA des Typs GE 2.75-120 durchgeführt. Parallel dazu konnten Anwohner Belästigungszeiträume über eine Geräuschmelde-App dokumentieren. In diesem Beitrag wird die Umsetzung einer interdisziplinären Messkampagne im Bereich des Tegelberg Windparks und eines Wohngebäudes in Tallage in ca. 1 km Entfernung zum Windpark beschrieben. Schließlich werden erste Ergebnisse der akustischen Messungen und interdisziplinären Untersuchung vorgestellt und diskutiert.Item Open Access Data processing, analysis, and evaluation methods for co-design of coreless filament-wound building systems(2023) Gil Pérez, Marta; Mindermann, Pascal; Zechmeister, Christoph; Forster, David; Guo, Yanan; Hügle, Sebastian; Kannenberg, Fabian; Balangé, Laura; Schwieger, Volker; Middendorf, Peter; Bischoff, Manfred; Menges, Achim; Gresser, Götz T.; Knippers, JanItem Open Access Rheology, dispersion, and cure kinetics of epoxy filled with amine‐ and non‐functionalized reduced graphene oxide for composite manufacturing(2021) Ackermann, Annika C.; Carosella, Stefan; Rettenmayr, Markus; Fox, Bronwyn L.; Middendorf, PeterThis study evaluates the effect of plasma surface functionalization of reduced graphene oxide particles on the processing characteristics and homogeneity of dispersion of a bisphenol A‐(epichlorhydrin) epoxy matrix and amine‐based hardener with varying weight fractions from 0.00 to 1.50 wt%. It was observed that amine‐functionalized reduced graphene oxide leads to a more drastic viscosity increase of up to 18‐fold of the uncured suspensions and that its presence influences the conversion rates of the curing reaction. Optical microscopy of thin sections and transmission electron microscopy analysis showed that a more homogeneous dispersion of the particles could be achieved especially at higher weight fractions by using an appropriate surface functionalization. This knowledge can be used to define suitable processing conditions for epoxies with amine‐based hardeners depending on the loading and functionalization of graphene‐related particles.Item Open Access The effect of pooling on the detection of the nucleocapsid protein of SARS-CoV-2 with rapid antigen tests(2021) Berking, Tim; Lorenz, Sabrina; Ulrich, Alexander; Greiner, Joachim; Kervio, Eric; Bremer, Jennifer; Wege, Christina; Kleinow, Tatjana; Richert, ClemensThe COVID-19 pandemic puts significant stress on the viral testing capabilities of many countries. Rapid point-of-care (PoC) antigen tests are valuable tools but implementing frequent large scale testing is costly. We have developed an inexpensive device for pooling swabs, extracting specimens, and detecting viral antigens with a commercial lateral flow test for the nucleocapsid protein of SARS-CoV-2 as antigen. The holder of the device can be produced locally through 3D printing. The extraction and the elution can be performed with the entire set-up encapsulated in a transparent bag, minimizing the risk of infection for the operator. With 0.35 mL extraction buffer and six swabs, including a positive control swab, 43 ± 6% (n = 8) of the signal for an individual extraction of a positive control standard was obtained. Image analysis still showed a signal-to-noise ratio of approximately 2:1 at 32-fold dilution of the extract from a single positive control swab. The relative signal from the test line versus the control line was found to scale linearly upon dilution (R2 = 0.98), indicating that other pooling regimes are conceivable. A pilot project involving 14 participants and 18 pooled tests in a laboratory course at our university did not give any false positives, and an individual case study confirmed the ability to detect a SARS-CoV-2 infection with five-fold or six-fold pooling, including one swab from a PCR-confirmed COVID patient. These findings suggest that pooling can make frequent testing more affordable for schools, universities, and similar institutions, without decreasing sensitivity to an unacceptable level.Item Open Access Development of a model predictive controller for floating offshore wind turbines(2020) Nann, SamuelIn this work, an Economic Model Predictive Controller for a floating offshore wind turbine is presented. The classical Model Predictive Control for floating offshore wind turbines provides promising results. In addition, research on onshore wind turbines revealed the potential of the economic control method, which can improve the closed-loop behavior and simplify the control design in comparison to the classical version of this control method. The aim of this work is, to develop a novel Economic Model Predictive Controller for a floating offshore wind turbine based on these two research results. A simplified low order model of a floating offshore wind turbine serves as a basis for the controller design. Including the disturbance preview and constraints, the controller computes optimal trajectories for the blade pitch and the generator torque. To apply the control technique to a floating offshore wind turbine two things have to be done: Firstly, the cost function is designed, to fulfill the main objectives of, maximizing the generated power and alleviating the structural fatigues. Secondly, the constraints are integrated into the control problem. After selecting a suitable solver, the controller is discretized and scaled, thus a proper implementation and smooth operation is possible. Afterwards, the successful functioning of the algorithm, a multi-objective optimization is done, to find appropriate weights to adjust the cost function for the required objectives. Finally, the developed controller is tested with realistic wind and wave disturbances. A significant reduction of the standard deviation of the generated power can be shown, while maintaining real time capability. Furthermore, the structural fatigues of the tower and the platform are decreased.Item Open Access IEA Wind Task 32: Wind Lidar : identifying and mitigating barriers to the adoption of wind lidar(2018) Clifton, Andrew; Clive, Peter; Gottschall, Julia; Schlipf, David; Simley, Eric; Simmons, Luke; Stein, Detlef; Trabucchi, Davide; Vasiljevic, Nikola; Würth, InesIEA Wind Task 32 exists to identify and mitigate barriers to the adoption of lidar for wind energy applications. It leverages ongoing international research and development activities in academia and industry to investigate site assessment, power performance testing, controls and loads, and complex flows. Since its initiation in 2011, Task 32 has been responsible for several recommended practices and expert reports that have contributed to the adoption of ground-based, nacelle-based, and floating lidar by the wind industry. Future challenges include the development of lidar uncertainty models, best practices for data management, and developing community-based tools for data analysis, planning of lidar measurements and lidar configuration. This paper describes the barriers that Task 32 identified to the deployment of wind lidar in each of these application areas, and the steps that have been taken to confirm or mitigate the barriers. Task 32 will continue to be a meeting point for the international wind lidar community until at least 2020 and welcomes old and new participants.Item Open Access Berechnung und Bewertung der Schallausbreitung von Windenergieanlagen mit Hilfe von Messdaten(2023) Häfele, Lorenz Karl