Fraunhofer-Institut für Windenergiesysteme IWES

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  • Publication
    From wind conditions to operational strategy: optimal planning of wind turbine damage progression over its lifetime
    ( 2023-11-20)
    Requate, Niklas
    ;
    Meyer, Tobias orcid-logo
    ;
    Hofmann, René
    Renewable energies have an entirely different cost structure than fossil-fuel-based electricity generation. This is mainly due to the operation at zero marginal cost, whereas for fossil fuel plants the fuel itself is a major driver of the entire cost of energy. For a wind turbine, most of the materials and resources are spent up front. Over its lifetime, this initial capital and material investment is converted into usable energy. Therefore, it is desirable to gain the maximum benefit from the utilized materials for each individual turbine over its entire operating lifetime. Material usage is closely linked to individual damage progression of various turbine components and their respective failure modes. In this work, we present a novel approach for an optimal long-term planning of the operation of wind energy systems over their entire lifetime. It is based on a process for setting up a mathematical optimization problem that optimally distributes the available damage budget of a given failure mode over the entire lifetime. The complete process ranges from an adaptation of real-time wind turbine control to the evaluation of long-term goals and requirements. During this process, relevant deterministic external conditions and real-time controller setpoints influence the damage progression with equal importance. Finally, the selection of optimal planning strategies is based on an economic evaluation. The method is applied to an example for demonstration. It shows the high potential of the approach for an effective damage reduction in different use cases. The focus of the example is to effectively reduce power of a turbine under conditions where high loads are induced from wake-induced turbulence of neighbouring turbines. Through the optimization approach, the damage budget can be saved or spent under conditions where it pays off most in the long term. This way, it is possible to gain more energy from a given system and thus to reduce cost and ecological impact by a better usage of materials.
  • Publication
    Wind turbine nacelle testing: State-of-the-art and development trends
    ( 2023-10-07)
    Siddiqui, Muhammad Omer
    ;
    Feja, Paul Robert
    ;
    Borowski, Philipp
    ;
    Kyling, Hans
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    Nejad, Amir R.
    ;
    Wenske, Jan
    Wind turbine nacelles are complex machines that are designed to operate under extreme loads and harsh environments. Extensive tests are performed throughout their development process to ensure that they can operate with high reliability. As both onshore and offshore wind turbine systems have rapidly evolved, so have the methods for testing the nacelle systems and subsystems. This paper presents the state of the art in wind turbine nacelle testing and the development trends in this field. It discusses the existing test requirements for certification and the different levels of testing that form part of a nacelle system’s development. The latest changes to the nacelle certification requirements are highlighted, along with several important research activities related to drivetrain testing. Future challenges for nacelle testing are identified and their potential solutions are proposed.
  • Publication
  • Publication
    Database of Short Term Damage Equivalent Loads (DEL) of IWT7.5MW wind turbine depending on wind, TI, yaw and derating
    ( 2023-09-28)
    Requate, Niklas
    ;
    Meyer, Tobias orcid-logo
    Two datasets for short term damage equivalent loads (DEL) and energy production of the IWT7.5 MW research wind turbine (https://doi.org/10.24406/IWES-N-518562) are provided. dataset_Derating is a subset of dataSet_Derating_withYaw. The damage equivalent loads are computed with the rainflow counting algorithm applied to time series loads. They are based on Miner's rule. Further details can be found in: Requate, N., Meyer, T., and Hofmann, R.: From wind conditions to operational strategy: Optimal planning of wind turbine damage progression over its lifetime, Wind Energ. Sci., accepted for publication, 2023. In the paper, the dataset_Derating was used to create surrogate models. A fullfactorial approach to simulate different parameter-combination was applied. Information about the signals and units is provided in the yml files. The range of parameters is given by python code in the yml file. For each set of parameters, 6 different 10 minute-realizations of a turbulent wind field ("seeds") were created. The turbine was then simulated separately for each turbulent wind field. Each folder contains the short term DELs for each 10 minute simulation and the aggregated short term DELs over all 6 wind realizations. Outliers from simulation error were removed. The data was originally intended to create surrogate models of the variation of outputs values throughout the parameter space. Further usage is possible and encouraged.
  • Publication
    Field-Data based Lab Testing of a Wind-Energy Power Converter System: Insights into Cabinet and IGBT-Module Microclimates
    ( 2023-09)
    Zorn, Christian
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    Peters, Jan-Hendrik
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    Hanf, Michael
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    Adler, Johannes
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    Holzke, Wilfried
    ;
    Pelka, Karoline
    ;
    Broer, Christian
    ;
    Fröhling, Sören
    ;
    Kostka, Benedikt
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    Wenzel, Johannes Christian
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    Mertens, Axel
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    Dehning, Kirsten Jonna
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    Zimmermann, Stefan
    ;
    Fischer, Katharina orcid-logo
    ;
    Kaminski, Nando
    IGBT power modules have been equipped with temperature/humidity sensors and integrated into a power converter system from the wind-power application. While exposed to climatic cycles, the power converter has been tested power-in-the-loop in a climate chamber. The test profile is a sequence of actual stress conditions recorded in a wind turbine converter operating in the field. During the tests, the internal conditions of the power modules and the power cabinet have been monitored. The resulting microclimates are examined when varying electrical loads coincide with climatic cycles.
  • Publication
    Improved cold-start behavior for alkaline electrolysis through electrolyte concentration heat storage
    ( 2023-08-29)
    Grewe, Fabian
    ;
    Zwaschka, Gregor
    ;
    Höflinger, Johannes
    In order to reduce the cold start-up phase of alkaline electrolysers, a concept for an accelerated heating process of an alkaline electrolyser was designed. The concept is based on the use of the exothermic dilution reaction of potassium hydroxide and water and was simulated using a extended cell model. The liquid electrolyte is diluted with water during a cold start and the heat of dilution thus released is used for accelerated heating. During operation of the electrolyser, water is consumed and thus the electrolyte is concentrated again.
  • Patent
    Oberflächenschwimmkörper, insbesondere Boje oder Tonne
    ( 2023-08-10)
    Viergutz, Thomas
    ;
    Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
    Die Erfindung bezieht sich auf einen Oberflächenschwimmkörper (1, 1a, 1b), insbesondere in Form einer Boje oder Tonne, zum ortsfesten Betrieb in einem offenen Gewässer, mit einer Vorrichtung (2, 2') zum Verankern des Oberflächenschwimmkörpers am Grund (3). Die Aufgabe, den Transport eines solchen Körpers zu erleichtern, wird gemäß der Erfindung dadurch gelöst, dass im schwimmenden Zustand der Oberflächenschwimmkörper oder wenigstens ein Teil des Oberflächenschwimmkörpers zwischen einer ersten und einer zweiten Position relativ zur Wasseroberfläche bewegbar ist, wobei die erste Position einem Transportzustand des Oberflächenschwimmkörpers und die zweite Position einem Betriebszustand entspricht und wobei der Strömungswiderstand im Transportzustand geringer ist als im Betriebszustand.
  • Patent
    Vorrichtung und Verfahren zur Drucksondierung von Böden
    ( 2023-08-03)
    Werpup Oguro, Aisgo
    ;
    Preu, Benedict
    ;
    Siemann, Lennart
    ;
    Hebig, Jan
    ;
    Pein, Taisiya
    ;
    Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
    Die Erfindung bezieht sich auf eine Drucksondiervorrichtung mit einer Sonde, die einen Sondierkonus (1) und insbesondere eine Mantelreibungshülse (2) sowie ein Inklinometer und einen Porendruckmesser aufweist, und mit einem Transportgestänge (4, 5, 6), das dazu eingerichtet ist, an einem ersten seiner Enden (7) mit der Sonde verbunden zu werden und diese unter Druckanwendung in einen zu sondierenden Bodenbereich zu drücken, sowie mit einer seismischen Messeinrichtung (9, 10, 11, 12) zur Erfassung von seismischen Signalen. Die Aufgabe, die seismischen Messdaten über mehrere Kanäle zu erfassen, wird dabei dadurch gelöst, dass die seismische Messeinrichtung mehrere seismische Sensoren (z. B. Drucksensoren, Accelerometer, Geophone) (9, 10, 11, 12) aufweist, die in ein oder mehrere Elemente (4, 5, 6) des Transportgestänges integriert und entlang der Längsrichtung des Transportgestänges mit Abstand voneinander angeordnet sind. Die verschiedenen seismischen Drucksensoren können ihre Messdaten in einen gemeinsamen Signalleiter (15) einspeisen.
  • Publication
    Oscillating rolling element bearings: A review of tribotesting and analysis approaches
    ( 2023-07-20)
    Presilla, Román de la
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    Wandel, Sebastian
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    Stammler, Matthias
    ;
    Grebe, Markus
    ;
    Poll, Gerhard
    ;
    Glavatskih, Sergei
    Rolling element bearings, when subjected to small oscillating movements or vibrations, run the risk of being damaged by mechanisms such as Standstill Marks and False Brinelling. Damages resulting from these phenomena can decrease bearing fatigue life and increase wear-induced friction torque. These failures do not correlate well with standard life estimation approaches. Experimental studies play a crucial role in gaining knowledge in this area. The review integrates knowledge from experiments ranging from single contacts to laboratory and full-scale bearings in wind power and aerospace applications. The generalization is achieved using a non-dimensional amplitude parameter that relates rolling element travel during an oscillation to the Hertzian contact size. The review encompasses testing methods, procedures, reporting practices, result scaling, and application-specific considerations.
  • Publication
    FOXES: Farm Optimization and eXtended yield Evaluation Software
    ( 2023-06-28)
    Schmidt, Jonas
    ;
    Vollmer, Lukas
    ;
    Dörenkämper, Martin
    ;
    Stoevesandt, Bernhard
    The Farm Evaluation and eXtended yield Evaluation Software (foxes) is a Python package that calculates wind farm results such as power production or wind turbine wake effects. The meteorological input data can be a timeseries or statistical data like wind speed histograms, wind roses or any other distribution. Uniform inflow fields are supported as well as horizontal profiles and three dimensional flow fields from other sources, for example wind fields from mesoscale weather models or wind atlases (Dörenkämper et al., 2020). Typical applications are wind farm optimization (e.g., layout optimization or wake steering), wind farm pre- and post-construction analyses; wake model studies, comparison and validation; and wind farm simulations invoking complex model interactions.