Publikationen

2021

• Influence of Continuous Provision of Synthetic Inertia on the Mechanical Loads of a Wind Turbine

  Gloe, A. ., Jauch, C. ., Craciun, B. ., Zanter, A. ., & Winkelmann, J. . (2021). Influence of Continuous Provision of Synthetic Inertia on the Mechanical Loads of a Wind Turbine. Energies, 14(16), 5185. http://doi.org/10.3390/en14165185

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  In many electrical grids, the share of renewable energy generation increases. As these generators are typically connected to the grid via inverters, the level of grid inertia decreases. Such grids may therefore suffer from high rates of change of frequency during power imbalances. Modern wind turbines can help in controlling the frequency in such grids by providing synthetic inertia. A controller to provide synthetic inertia with wind turbines was developed at the Wind Energy Technology Institute in collaboration with Suzlon Energy. For this controller the influence of providing synthetic inertia on the mechanical loads of the wind turbine is assessed for different grid frequency scenarios. Such a scenario-based load analysis has not been published before, especially as the scenarios are derived from real measurements. The effect of the loads strongly depends on the analyzed grid frequency behavior. Ten months of high quality grid frequency measurements of the Indian grid are analyzed in order to derive inputs for the load calculation. Different types of grid frequency abnormities are identified and categorized with respect to their severity. Based on the observed occurrences of the grid frequency abnormities, realistic scenarios for the load calculations are chosen. The load calculations are performed for a state-of-the-art Suzlon wind turbine generator. The load increases caused by the supply of synthetic inertia are calculated for individual components assuming an otherwise undisturbed power production of the wind turbine in turbulent wind. Furthermore, a hardware-in-the-loop test bench is used to show how the measured grid frequencies are actually perceived by the control system of a typical wind turbine. The original frequency data were recorded with high quality measurement equipment, which is faster and more accurate than a multi-function relay, often used in wind turbines. For exemplary time traces, the effect of the reduced measurement accuracy on the reaction of the wind turbine is shown. This aspect has not been investigated in the literature yet. The results show that wind turbines can provide synthetic inertia without a considerable effect on the lifetime of the wind turbine. However, there are still problems with providing synthetic inertia reliably at high power operating points, which have to be solved.

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    • Gloe, Arne
    • Jauch, Clemens

  • Abteilung/Einrichtung

    • Wind Energy Technology Institute

  • Fachbereich

    • Fachbereich 2: Energy and Life Science

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  • 2021
  • Journal Article
  • • Arne Gloe
    • Prof. Dr. Clemens Jauch
    • B. Craciun
    • Arvid Zanter
    • J. Winkelmann
  • • WETI

• Subsurface renewable energy storage capacity for hydrogen, methane and compressed air – A performance assessment study from the North German Basin

  Gasanzade, F. ., Pfeiffer, W. T., Witte, F. ., Tuschy, I. ., & Bauer, S. . (2021). Subsurface renewable energy storage capacity for hydrogen, methane and compressed air – A performance assessment study from the North German Basin. Renewable and Sustainable Energy Reviews, 149, 111422. http://doi.org/https://doi.org/10.1016/j.rser.2021.111422

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  The transition to renewable energy sources to mitigate climate change will require large-scale energy storage to dampen the fluctuating availability of renewable sources and to ensure a stable energy supply. Energy storage in the geological subsurface can provide capacity and support the cycle times required. This study investigates hydrogen storage, methane storage and compressed air energy storage in subsurface porous formations and quantifies potential storage capacities as well as storage rates on a site-specific basis. For part of the North German Basin, used as the study area, potential storage sites are identified, employing a newly developed structural geological model. Energy storage capacities estimated from a volume-based approach are 6510 TWh and 24,544 TWh for hydrogen and methane, respectively. For a consistent comparison of storage capacities including compressed air energy storage, the stored exergy is calculated as 6735 TWh, 25,795 TWh and 358 TWh for hydrogen, methane and compressed air energy storage, respectively. Evaluation of storage deliverability indicates that high deliverability rates are found mainly in two of the three storage formations considered. Even accounting for the uncertainty in geological parameters, the storage potential for the three considered storage technologies is significantly larger than the predicted demand, and suitable storage rates are achievable in all storage formations.

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    • Witte, Francesco
    • Tuschy, Ilja

  • Profilbereich

    • Erneuerbare Energien und nachhaltige Entwicklung

  • Forschungsfeld

    • Wärme
    • Netzintegration

  • Fachbereich

    • Fachbereich 2: Energy and Life Science

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  • 2021
  • Journal Article
  • • Firdovsi Gasanzade
    • Wolf Pfeiffer
    • Francesco Witte
    • Ilja Tuschy
    • Sebastian Bauer
  • • Subsurface energy storage
    • Storage capacity
    • Exergy assessment
    • North German Basin
    • Geological porous media
    • Compressed air energy storage
    • Hydrogen gas storage
    • Methane gas storage
    • Achievable storage rate

• Implementation of Variable Blade Inertia in OpenFAST to Integrate a Flywheel System in the Rotor of a Wind Turbine

  Alhrshy, L. . (2021). Implementation of Variable Blade Inertia in OpenFAST to Integrate a Flywheel System in the Rotor of a Wind Turbine. Energies, 14. http://doi.org/10.3390/en14102783

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  In this paper, the integration of the dynamic behavior of the flywheel system into the load simulation tool OpenFAST is presented. The flywheel system enables a wind turbine to vary the inertia of its rotor blades to control the power production and, most importantly, to affect the vibratory behavior of wind turbine components. Consequently, in order to simulate the behavior of a wind turbine with a flywheel system in its rotor, the variable blade characteristics need to be considered in the load simulation tool. Currently, computer-aided engineering tools for simulating the mechanical loads of wind turbines are not designed to simulate variable blade inertia. Hence, the goal of this paper is to explain how variable inertias of rotor blades are implanted in such load simulation tools as OpenFAST. OpenFAST is used because of it is free, publicly available, and well documentation. Moreover, OpenFAST is open source, which allows modifications in its source code. This add-on in the load simulation is applied to correct rotor mass imbalance. It can also be applied in many cases related to the change in the inertia of wind turbine rotor blades during its operation as, for example, atmospheric ice accretion on the blades, smart blades, etc.

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    • Alhrshy, Laurence

  • Forschungsprojekt

    • Schwungrad

  • Abteilung/Einrichtung

    • Wind Energy Technology Institute

  • Fachbereich

    • Fachbereich 2: Energy and Life Science

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  • 2021
  • Journal Article
  • • Laurence Alhrshy

• Entrepreneurship Education als Beitrag zur Weiterung der Horizonte

  Ebbers, I. . (2021). Entrepreneurship Education als Beitrag zur Weiterung der Horizonte.

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  [... Der Beitrag] verfolgt die Frage, wie eine Entrepreneurship Education, verstanden als Erziehung zum unternehmerisches Denken und Handeln, im Rahmen allgemein-bildender Beschulung und mit dem Ziel einer allgemeinbildenden Wirksamkeit so angelegt werden kann, dass sie einen Beitrag zur Horizontweitung der Lernenden leisten kann. Um diese Frage beantworten zu können, soll im weiteren Verlauf der Bildungsbegriff nach Klafki genutzt werden. Er bezieht sich hier im Wesentlichen auf vier Aufgaben der Bildung, welche im Folgenden vor dem Hintergrund der hier gemeinten Entrepreneurship Education genauer betrachtet werden sollen. (DIPF/Orig.).

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  • Abteilung/Einrichtung

    • Jackstädt-Zentrum Flensburg (JZF)

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  • 2021
  • Miscellaneous
  • • Ilona Ebbers

• Software-in-the-Loop Simulation of a Gas-Engine for the Design and Testing of a Wind Turbine Emulator

  Rohr, A. ., & Jauch, C. . (2021). Software-in-the-Loop Simulation of a Gas-Engine for the Design and Testing of a Wind Turbine Emulator. Energies, 14. http://doi.org/10.3390/en14102898

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  In order to investigate the grid integration of wind turbines (WT) of various scales and designs, a wind turbine emulator (WTE) is being built in Flensburg within the state-funded project GrinSH. The special feature of this WTE is the use of a large gas engine instead of an electric motor to emulate the behavior of a WT. In order to develop the controls of this innovative WTE and to design the upcoming test runs under safe conditions, a software in the loop model (SILM) was applied. This SILM contained a mathematical model of the wind turbine, mathematical models of the gas engine with an integrated controller, and a model of the generator and frequency converter unit, as well as a preventive modulator of the reference signal (PMRS). The PMRS module converts the reference signal of the emulated WT in such a way that the dynamics of the engine components can be calculated and balanced in advance to enable the required behavior of the entire SILM despite the dynamics of the gas engine. It was found that the PMRS module, developed and tested in this work, increased the ability of the WTE, based on a gas engine, to reproduce the dynamics of a WT.

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  • Personenseiten

    • Rohr, Alexander
    • Jauch, Clemens

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  • 2021
  • Journal Article
  • • Alexander Rohr
    • Prof. Dr. Clemens Jauch

• Spielwiese und Impulsgeber zugleich : wie Corporate Influencer die Organisation verändern

  Reimer, T. ., Heidenreich, M. ., & Herbert, O. . (2021). Spielwiese und Impulsgeber zugleich : wie Corporate Influencer die Organisation verändern. Organisationsentwicklung : Zeitschrift für Unternehmensentwicklung und Change Management. Düsseldorf: Solutions by Handelsblatt Media Group GmbH.

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    • Jackstädt-Zentrum Flensburg (JZF)

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  • 2021
  • Miscellaneous
  • • Tanja Reimer
    • Markus Heidenreich
    • Oliver Herbert

• Biased Preferences for Wealth Taxation: The Case of Misperceived Tax Burden Consequences

  Chirvi, M. ., Huber, H.-P. ., & Schneider, C. . (2021). Biased Preferences for Wealth Taxation: The Case of Misperceived Tax Burden Consequences. TRR 266 Working Paper Series.

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  The individual capacity to form personal preferences constitutes an essential element of thedemocratic process. At the same time, policies with far-reaching consequences often require profound expertise. Taxation is such an example. Due to its complex character, bounded rationality might induce biases causing other outcomes than intended. This paper quantifies shifts in stated preferences for wealth taxation caused by misperceived burden consequences of commonly politically discussed tax parameters: tax allowances and tax rates. For this, we conducted a randomized survey experiment with over 1,200 respondents in Germany. In a 2 by 2 design, our respondents were randomly selected to indicate both their preferred tax allowance and tax rate for either a yearly or a one-time wealth tax. Our treatment group was provided with easy-to-understand information on the resulting effective lifetime tax burden for the respective instrument. We find the preferred effective tax rate to drop by almost 15 percentage points for a yearly wealth tax if our participants are fully informed, whereas we do not find this effect for the one-time wealth tax. In terms of informed preferences our respondents preferthe yearly wealth tax over a one time wealth tax if misperceptions are resolved: the preferred effective tax burden of a yearly wealth tax is about 25 percentage points higher (40.0% vs.15.2%). While not being able to fully explain the source of this difference, we argue that both the total burden as well as the reasonability of single payments might be factors that form preferences for tax parameters.

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    • Chirvi, Malte

  • Fachbereich

    • Fachbereich 4: Wirtschaft

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  • 2021
  • Unpublished
  • • Malte Chirvi
    • Hans-Peter Huber
    • Cornelius Schneider

• fluprodia (Fluid Property Diagram)

  Witte, F. . (2021). fluprodia (Fluid Property Diagram). Zenodo. http://doi.org/10.5281/ZENODO.3795771

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    • Witte, Francesco

  • Fachbereich

    • Fachbereich 2: Energy and Life Science

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  • 2021
  • Miscellaneous
  • • Francesco Witte
  • • Fluid Property Diagram
    • Thermodynamics
    • Phases
    • Isoline

• Exploration vs. limitation – An investigation of instructional design techniques for spatial ability training on mobile devices

  Montag, M. ., Bertel, S. ., de Koning, B. B., & Zander, S. . (2021). Exploration vs. limitation – An investigation of instructional design techniques for spatial ability training on mobile devices. Computers in Human Behavior, 118, 106678. http://doi.org/https://doi.org/10.1016/j.chb.2020.106678

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  Spatial abilities and thus mental rotation skills predict achievement in STEM domains. Thus, a wide range of studies investigated the possibilities and trainings of mental rotation skills. One prominent approach is using different digital tools and representation formats to foster spatial abilities. Thereby numerous studies analyzed effects of static in comparison to interactive dynamic representations of mental rotation tasks using different types of interactions. Although the use of dynamic representations is discussed critical regarding superficial information processing, there are no studies to date varying instructional techniques in interactive dynamic spatial trainings. In two studies we compared Limited Rotation training to non-limited Free Rotation training with high school students (Npilot = 21, Nmain = 66). Results after training show a superior effect of the limited compared to the non-limited training regarding the students’ success rate, but not their motivation and mental demand. Additionally analyzed process data show more efficient ways of task solving after limited rotation training indicated by reduced response time and rotation way accompanied by higher success rates in solving non-limited rotation tasks. Results of a pre-and-post-comparison of mental rotation skills indicate a higher increment after limited rotation training. Over-facilitating effects of dynamic representations are discussed.

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    • Bertel, Sven

  • Abteilung/Einrichtung

    • CIVU – Center for Interaction, Visualization and Usability

  • Fachbereich

    • Fachbereich 3: Information und Kommunikation

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  • 2021
  • Journal Article
  • • Michael Montag
    • Sven Bertel
    • Bjorn de Koning
    • Steffi Zander
  • • Spacial abilities
    • STEM
    • Multimedia learning
    • mental rotation

• Financial performance and firm efficiency of automotive manufacturers and their suppliers A longitudinal data envelopment analysis

  Brandenburg, M. ., & Hahn, G. J. (2021). Financial performance and firm efficiency of automotive manufacturers and their suppliers A longitudinal data envelopment analysis. Logistics Research, 14(1), 26. http://doi.org/10.23773/2021_01

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  A data envelopment analysis (DEA) is presented to assess evolutions of firm efficiency and financial performance in automotive supply chains. A sample of 32 decision-making units (DMUs), 17 globally operating original equipment manufacturers (OEMs) and 15 key suppliers from the automotive industry, is in focus of this analysis in which cost levels and capital requirements are put into relation to sales growth and profit. Cost of goods sold, operating capital, and net fixed assets represent the financial input of a company while sales growth and earnings before interest and taxes (EBIT) reflect the financial output. The financial performance of a firm is indicated by its efficiency, calculated by an input-oriented variable returns to scale model. A multiple linear regression analysis reveals which operational performance factors are predictors of financial performance. A longitudinal DEA approach that covers the years from 2003 to 2017 is chosen to reveal performance evolutions over time. In order to analyze the stability of relationships between efficient firms (peers) and inefficient ones (followers) over time, changes in the performance relationship network are assessed in a graph-theoretic approach. In this study, geographical and structural specifics of DMU groups are taken into account. The study reveals similarities and differences between OEMs and their suppliers regarding the importance of value drivers and detects periods of performance losses and recovery from the global economic crisis.

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    • Brandenburg, Marcus

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  • 2021
  • Journal Article
  • • Marcus Brandenburg
    • Gerd Hahn
  • • Automotive industry
    • Data Envelopment Analysis
    • Financial performance
    • Supply networks