Now showing 1 - 10 of 413
  • Publication
    Field-measurement based hygrothermal modelling of the converter-cabinet climate in wind turbines
    ( 2022-10) ;
    Gohler , Katherina
    Power converters in wind turbines suffer from frequent failures. Root-cause analyses point to environmental influences as important drivers of converter failure. Based on comprehensive field measurements in wind turbines, we derive hygrothermal models describing the dependence of temperature and humidity in the converter cabinet on the ambient climatic conditions and turbine operation. The results show that lumped-parameters models of minimal complexity are suitable for describing the conditions with reasonable accuracy and that publicly available ERA5 reanalysis data may be used to consider the site-specific climatic conditions outside of the wind turbine. In addition, we demonstrate that the hygrothermal model derived for a turbine type can successfully be transferred to identical turbines operating in other countries. The models can therefore serve as a basis for refined requirement specifications as well as for the derivation of application-specific test procedures for power converters and their components.
  • Publication
    Aktuelle Untersuchungen an Suction Buckets für Offshore‐Windenergieanlagen - das ProBucket‐Projekt
    ( 2022-08-15) ;
    Quiroz López, Tulio Ernesto
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    Binsker, Georg
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    Sanders, Immo
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    Achmus, Martin
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    Collmann, Mareike
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    Böhm, Manuela
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    Schaumann, Peter
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    Elsesser, Waldemar
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    Schädlich, Bert
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    Kirsch, Fabian
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    Richter, Thomas
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    Gose, Manfred
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    Pehl, Peter
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    Kleineidam, Patric
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    Maas, Justus
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    Ibis, Sercan
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    Oltmann, Klaas
    Suction Buckets sind etablierte Gründungselemente für Offshore-Öl- und -Gasplattformen, die bisher in der Offshore-Windindustrie nur vereinzelt eingesetzt wurden. Diese Fundamente können zusammen mit der Unterstruktur installiert werden, wodurch zusätzliche Offshore-Operationen wie das Grouting von Transition Pieces oder von Jacket-Beinen vermieden werden. Außerdem werden bei der Installation von Suction Buckets, im Gegensatz zu Pfahlgründungen, minimale akustische Emissionen erzeugt, sodass zusätzliche schallreduzierende Maßnahmen überflüssig sind. Aus diesen Gründen gelten Suction Buckets als eine praktikable und potenziell kostengünstige Gründungslösung für Offshore-Windenergieanlagen (OWEA). Das Forschungsvorhaben ProBucket wurde 2020 initiiert und wird vom Bundesministerium für Wirtschaft und Klimaschutz (BMWK) gefördert. Durch die geplanten vielfältigen physikalischen und numerischen Untersuchungen strebt das Vorhaben an, die Unsicherheiten der existierenden Bemessungsverfahren zu verringern. In diesem Beitrag werden die aktuellen Herausforderungen zum Design und zur wirtschaftlichen Umsetzung von Suction Buckets für OWEA erläutert. Darüber hinaus werden die Forschungsaktivitäten von ProBucket beschrieben.
  • Publication
    Wind speed reconstruction from three synchronized short-range WindScanner lidars in a large wind turbine inflow field campaign and the associated uncertainties
    ( 2022)
    Giyanani, Ashim
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    Sjöholm, M.
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    Rolighed Thorsen, G.
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    Schuhmacher, Jakob
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    Modern large wind turbines require high-resolution wind measurements as input to aerodynamic and aeroelastic simulations for modelling and validation purposes. Within the HighRe project, we aim at studying the aerodynamic effects at high Reynolds numbers by measuring four-dimensional wind fields (vx ,vy ,vz ,t) using three short-range WindScanners (SRWS). The systems were set up at the test site in Bremerhaven (Testfeld BHV) to perform an inflow wind field measurement campaign. In order to get a better understanding of the measurements, we describe the propagation of uncertainties in SRWS parameters to the measured wind field and propose an uncertainty model for a measurement setup with three SRWS lidars. In this study, we first evaluate the wind reconstruction and derive an uncertainty model for the wind components vx, vy, and vz, which are mainly dependent on the input parameters, e.g., focus range, elevation angle, and azimuth angle. The effective intersection diameter at the intersection of three beams was found to be in the order of 2-5m. As expected, a high uncertainty was observed at lower heights in the vz -component due to low elevation angles. This uncertainty evaluation forms the basis for comparing scanning patterns with regard to their accuracy in providing four-dimensional measurements.
  • Publication
    Modelling the Rotating Subsystem
    ( 2022)
    Gambier, Adrian Hector
    The rotating subsystem is a key part of a wind turbine and, on the other hand, it is the most problematic to be modelled, where flexible beams are transformed in an assembly of rigid bodies connected by joints and spring-damper devices. Models are then classified by the number of masses considered. Several simplifications are assumed and some abstraction processes are applied in order to derive a dynamic model for control. The models are presented in an increasing degree of complexity. Thus, the user can select the model according to the control problem in the study. A simulation example illustrates the characteristics of the different models including poles and natural frequencies and execution time.
  • Publication
    Supervisory Control
    ( 2022)
    Gambier, Adrian Hector
    The operation of large wind turbines requires an efficient control system in order to have a stable and optimal behaviour for all operational states. The control system consists, in general, of several control loops with multiple controllers, which have to be managed by a supervisor depending on the current operational state of the machine. The present chapter describes the implementation of a supervisory control system by using a hybrid automaton, whose function is to switch control loops and controllers according to the current operational state of the machine.
  • Publication
    Modelling the Tower Subsystem
    ( 2022)
    Gambier, Adrian Hector
    High towers are flexible and therefore and in the case of very large rotors, the flexibility of the tower is moderate compared with the blades. Despite this moderate flexibility, tower vibrations have an impact on the rest of the structure. In the modelling of the tower, three increasing levels of complexity can be observed in the literature. One is the tower with a large mass at the top without a rotor. The dynamics consider only the first natural frequency in the fore–aft direction. The second motion in a sideway direction with similar dynamics can also be added. The second level consists of models that reflect the blade–tower interaction but only in the flapwise/fore–aft direction for the first natural frequencies of the blade and tower. The third level is determined by the number of external forces and moments considered in the model. The models are presented in this order in the chapter.
  • Publication
    Preface
    ( 2022)
    Gambier, Adrian Hector
  • Publication
    Yaw Control and Shutdown Control
    ( 2022)
    Gambier, Adrian Hector
    In the previous chapters, the control system and control strategies for the most important operational states are described. Other control tasks are also present in the system and in other operational states. One of them is the yaw control that takes place all the time but begins in Region I, which corresponds to the operational state Standby.
  • Publication
    Identification of torsional frequencies of a large rotor blade based on measurement and simulation data
    ( 2022) ;
    Huhn, Matthias Leonhard
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    With increasing size of wind turbines, the aerodynamic and structural properties of the rotor blades become more and more important. However, studies investigating the torsional properties using measurement data and simulation results on full-size turbines are still scarce. In this study, torsional measurements are carried out on a large wind turbine with a rotor diameter of 180 m and compared with model results. In this study, torsional measurements on a large wind turbine with a rotor diameter of 180 m are conducted and compared with model results. Torsional parameters of a rotor blade are identified using two different measurement methods, the first based on strain gauges and the second based on accelerometers. Both methods show frequencies that can be associated with the natural frequencies of the two first torsional modes of the rotor blade. To extract the natural frequencies and to reduce external effects, a manual pitching procedure is evaluated. Here, the first two natural frequencies associated with torsional modes can be identified. In a second step, the behaviour of the blade during power production is investigated and compared with the simulation results.
  • Publication
    Digitalization Workflow for Automated Structuring and Standardization of Maintenance Information of Wind Turbines into Domain Standard as a Basis for Reliability KPI Calculation
    Maintenance data of wind turbines is an important information source for calculating key performance indicators. Also, it can be used for developing models for early fault detection. Both activities aim for supporting informed decisions in operation and maintenance. However, such data is rarely available in a structured and standardized format which hinders the interoperability of different enterprises. Consequently, maintenance information is often unused or only usable with considerable personnel effort. To digitalize wind farm maintenance, a digitalization workflow is developed and presented in this paper. The workflow consists of the steps optical character recognition, information extraction and text classification. The workflow is applied on real-world wind turbine service reports and invoices. First results for each step show good performance metrics and potential for further real-world application of the proposed method.