Jauch, C. . (2021). Grid Services and Stress Reduction with a Flywheel in the Rotor of a Wind Turbine. Energies, 14. http://doi.org/10.3390/en14092556
Abstract
Wind power penetration increases in most grids and the sizes of wind turbines increase. This leads to increasingly tough requirements, which are imposed on wind turbines, both from the grid as well as from economics. Some of these partially contradictory requirements can only be satisfied with additional control mechanisms in the wind turbines. In this paper, such a mechanism, i.e., a hydraulic–pneumatic flywheel system in the rotor of a wind turbine, is discussed. This flywheel system supports a wind turbine in providing grid services such as steadying the power infeed, fast frequency response, continuous inertia provision, power system stabilization, and low voltage ride-through. In addition, it can help mitigate the stress on the mechanical structure of a wind turbine, which results from varying operating points, imbalances in the rotor, gravitation that acts on the blades, in-plane vibrations, and emergency braking. The study presented in this paper is based on simulations of a publicly available reference wind turbine. Both the rotor blade design as well as the design of the flywheel system are as previously published. It is discussed how the aforementioned grid services and the stress reduction mechanisms can be combined. Finally, it is concluded that such a flywheel system broadens the range of control mechanisms of a wind turbine substantially, which is beneficial for the grid as well as for the wind turbine itself.
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
Abstract
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.
Pornak, S. C., Papachrysanthou, A. ., & Lehr, B. . (2021). Apps und webbasierte Interventionen in der Prostatakrebsnachsorge – ein Scoping Review. Der Urologe, 60, 911–920.
Kugler, M. ., Brandenburg, M. ., & Limant, S. . (2021). Automizing the manual link in maritime supply chains? An analysis of twistlock handling automation in container terminals. Maritime Transport Research, 2, 100017. http://doi.org/https://doi.org/10.1016/j.martra.2021.100017
Abstract
The study at hand elaborates on potential barriers, prerequisites and optimization potentials for the automation of the twistlock handling process in container terminals. A case analysis enlightens latest automation developments of this essential task in container transport. Eight experts from different organizations in maritime logistics and seaport operations were interviewed in a qualitative multiple-case research design. The interviews were evaluated by qualitative-quantitative content analysis with MAXQDA software. Automated twistlock handling systems are hardly implemented, although they represent the missing link between other container handling technology in the automated container transport. The study reveals that most implementation barriers consist of technological issues, followed by economic and strategic barriers. The study identifies implementation strategies and their key success and shows that safety improvements and cost reductions are major benefits of this automation. An innovation framework for this field of automation is conceptualized as scientific contribution. Practical implications include recommendations for relevant stakeholders in container logistics.
Petersen, K. ., & Bin Ali, N. . (2021). An analysis of top author citations in software engineering and a comparison with other fields. Scientometrics, 126, 9147–9183.
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
Abstract
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.
Pfeiffer, W. T., Witte, F. ., Tuschy, I. ., & Bauer, S. . (2021). Coupled power plant and geostorage simulations of porous media compressed air energy storage (PM-CAES). Energy Conversion and Management, 249, 114849. http://doi.org/https://doi.org/10.1016/j.enconman.2021.114849
Abstract
Porous media compressed air energy storage (PM-CAES) systems that use porous geological formations such as sandstone may provide large storage capacities in future energy systems based primarily on fluctuating renewable energy sources. In CAES systems, the instantaneous power and stored energy are closely linked to the storage pressure and the mass flow rate achievable in the geological reservoir. Therefore, a coupled simulator that accurately represents the power plant, the geostorage site, and their interactions during all potential PM-CAES system operation modes is presented in this paper. Using adiabatic and diabatic power plant topology test designs, strong feedback between the achievable storage rates and capacities of the chosen power plant design and geostorage site are found, thus confirming the benefit of this integrated modelling approach. Using a generic, highly cyclic load profile for daily peak shaving with charging and discharging rates of 100 MW and an adiabatic power plant topology, it is found that all discharging targets can be met but the achievable charging rates decrease to approximately 95 MW due to increased pressure in the geostorage after approximately 10 cycles. When a diabatic power plant design is considered, a long-term decrease in the geostorage pressure is found. Correspondingly, the charging power always meets the specifications, while the discharging power decreases slowly from the 20th storage cycle onwards to 79 MW in the 31st cycle. The newly developed simulation tool thus allows one to predict achievable power rates and geostorage pressures for PM-CAES systems, enabling the identification of efficient PM-CAES designs.
Ivannikov, V. ., Thomsen, F. ., Ebel, T. ., & Willumeit-Römer, R. . (2021). Capturing shrinkage and neck growth with phase field simulations of the solid state sintering. Modelling and Simulation in Materials Science and Engineering, 29(7). http://doi.org/10.1088/1361-651X/ac1f87
Irshad, M. ., Britto, R. ., & Petersen, K. . (2021). Adapting Behavior Driven Development (BDD) for large-scale software systems. Journal of Systems and Software, 177, 110944.