Schulz, Detlef
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- PublicationOpen AccessDrone-aided electrical current sensing - a breakthrough for smart gridsThis paper serves as an overview of the current progress concerning the DNeD (Digitalized, legally safe and low-emission airborNe inspection and grid data acquisition using automated Drones) project. DNeD aims to provide a full solution of an intelligent current sensor, integrable inside a dedicated drone-embedded sensor box. The research began with a brief survey of non-invasive current sensing technologies as a guide for the selection of the optimum current sensing physics. Afterwards, an all-optical sensor (MICATU RG235) was tested under laboratory conditions. The results from these tests were systematically tabulated. Concurrently, a study on magnetic field-based current sensing was performed using Finite Element Analysis (FEA) in COMSOL. This dual approach allows for a comprehensive evaluation of different sensing technologies. Ultimately, the study concludes that magnetic-based sensing, utilizing Hall effect sensors (e.g. DRV5055), is by far the most suitable approach. Additionally, the design of the sensor-box housing considered crucial mechanical factors such as robustness and weight. The design process utilized CAD models developed in SolidWorks, which form the backbone for real sensor-box manufacturing. Overall, the circuitry suggestions consisted of the development of analogue modulation electronic circuits, incorporating low pass filters, voltage dividers, and additional protective circuitry to ensure the reliability and accuracy of the sensor data. A prototype was developed, featuring Bluetooth as the communication protocol between the sensor-box and a remote system running MATLAB. Preliminary results indicate that the prototype effectively transfers dummy analogue voltage signals over distances up to 30 metres, demonstrating the feasibility of the design for practical applications. This comprehensive study not only addresses the mechanical and physical design aspects of embedding an intelligent sensor in a drone but also explores various current sensing technologies and their practical implementation. The findings provide a robust framework for future development and optimization of intelligent sensor systems in aerial applications.
- PublicationOpen AccessCoupleIT! Coupling energy grids and research disciplines(UB HSU, 2024-12-20)
; ; ; ; ; ; ; ; ;Bornholdt, Heiko ;Fischer, Mathias ;Steller, RubinaSchweizer-Ries, PetraThe dtec.bw project CoupleIT! – IT-based sector coupling: Digitally controlled fuel cell and electrolyzer technologies for stationary and mobile applications is an interdisciplinary approach to combine a wide range of competencies from disciplines as varied as electrical power systems, economic and social sciences, computer sciences and networks as well as sustainable development and social acceptance research. As such, this article is composed of individual contributions, constituting the main chapters that showcase general approaches and motivations but also concrete results. This compendium article starts in with a delineation of the motivation behind research in so-called microgrids composed of fuel cell and electrolyzer components and a presentation of the microgrid architecture opted for in this project. Chapter two goes into more detail on the side of electrical engineering and the feasibility of a parallel operation of inverters in microgrids to achieve the ability for an upscaling. Chapter three highlights economic and technological factors for an economically viable and grid-maintaining deployment of a hydrogen-based energy system. In addition, degradation of Li-ion batteries is discussed against the background of their flexible operation in a microgrid and other scenarios. Chapter four grants a glimpse into the field of computer science and the possibility to use artificial intelligence and neural networks for a new way to simulate the behaviour of matter on atomic and molecular scales. This approach holds potential to increase the efficiency of fuel cells by improving the molecular design of fuel cell membranes used within this project. Chapter five elucidates the intricacies of secure communication within one but also between multiple microgrids, an important aspect for achieving a resilient system. Chapter six concludes this compendium by highlighting the human perspective seen from the field of psychological acceptance research nested in the broader context of sustainable development. Among other things, areas of potential barriers to a public acceptance of hydrogen technology are identified and ways to overcome those barriers proposed. This interdisciplinary round trip starts with electrical engineering (chapters one and two), economic and social sciences (chapter three), followed by computer sciences (chapter four) and computer networks (chapter five) whence the baton is passed for one last time to the field of sustainable development and psychological acceptance research (chapter six). - PublicationOpen AccessElektrische Lastkraftwagen und Zugmaschinen in Hamburg im Jahr 2050Eine umfassende Analyse der künftigen Elektrifizierungsszenarien im Verkehrssektor ist entscheidend, um Auswirkungen auf das Stromnetz rechtzeitig zu erkennen und zu bewältigen. Dieser Bericht prognostiziert die Anzahl der elektrischen Lastkraftwagen und Zugmaschinen, die bis 2050 in Hamburg im Einsatz sein werden, sowie den resultierenden Energieverbrauch in den einzelnen Stadtteilen bis 2050. Drei Szenarien werden erarbeitet, um unterschiedliche Entwicklungen und Annahmen zur Elektrifizierung und Energienutzung im Güterverkehr abzubilden. Außerdem wird eine Lineare Programmierung (LP) zur Optimierung der Verteilung in der Stadt genutzt, um die effizienteste und nachhaltigste Verteilung der elektrischen Lasten in den verschiedenen Stadtteilen zu ermitteln. Die Ergebnisse können als Grundlage für Strategien zur Integration der elektrischen Lastkraftwagen und Zugmaschinen in das Stromnetz in Hamburg dienen.
- PublicationOpen AccessModifizierter PSO-Algorithmus für verbessertes MPPT bei der PV-LeistungsoptimierungPhotovoltaische (PV) Systeme leiden unter suboptimaler Leistungsausbeute bei Teilabschattungsbedingungen, bedingt durch wechselnde Umweltfaktoren wie Einstrahlung, Temperatur und partielle Verschattung. Diese Arbeit stellt einen innovativen Algorithmus zum Maximum Power Point Tracking (MPPT) vor, der auf der Partikelschwarmoptimierung (PSO) basiert. Das Ziel ist es, unter herausfordernden Bedingungen den globalen Maximum Power Point (MPP) präzise zu lokalisieren und zu verfolgen. Im Gegensatz zu konventionellen PSO-basierten MPPT-Verfahren, die oft unter langen Konvergenzzeiten oder Oszillationen während der Suche leiden, integriert der vorgestellte Ansatz eine adaptive Anpassungsstrategie. Diese Modifikation ermöglicht eine signifikante Verbesserung der Leistungsfähigkeit, charakterisiert durch minimale stationäre Schwingungen und eine schnelle Anpassung an sich ändernde Umgebungsbedingungen. Die Effektivität des vorgeschlagenen Algorithmus wird durch umfangreiche Simulationen in MATLAB/SIMULINK demonstriert. Die Ergebnisse werden detailliert analysiert und mit etablierten PSO-Varianten verglichen, wobei die überlegene Performance des neuen Ansatzes in Bezug auf Konvergenzgeschwindigkeit, Stabilität und Effizienz der MPP-Verfolgung hervorgehoben wird. Diese Arbeit leistet einen weiteren Beitrag zur Optimierung von PV-Systemen unter realen, variablen Betriebsbedingungen.
- PublicationOpen AccessUntersuchung der Versorgungsresilienz bei Schiffen mit elektrischen Gleichspannungsbordnetzen in Hinblick auf Spannungsqualität(Die Deutsche Gesellschaft für Wehrtechnik e. V. (DWT), 2024-09-24)
; Die Bedeutung der elektrischen Energieversorgung in maritimen Systemen, insbesondere vor dem Hintergrund technologisch hochentwickelter Schiffe wie Passagierschiffe und Tanker, kann nicht unterschätzt werden. Die Betriebssicherheit und Zuverlässigkeit dieser Systeme wird erheblich durch die Qualität der Stromversorgung beeinflusst. Ereignisse wie der Unfall auf der RMS Queen Mary 2 im Jahr 2010 verursacht durch den Ausfall eines Oberschwingungsfilters, verdeutlichen die kritische Notwendigkeit einer kontinuierlichen Überwachung und Bewertung der Netzqualität. - PublicationMetadata onlyAn overview of the selection process for contactless electrical sensors used in overhead transmission lines’ monitoringThis paper serves as a quick guide for the selection process of contactless electrical sensors involved in unmanned aerial systemsbased gridmonitoring applications. Since the selection criteria for such sensors can be enormous and hence challenging, the major key points were elaborated after a thorough review of relevant work. The review presented in this paper, composedof seven current sensors and three voltage sensors topologies, is critically investigated. In terms of flexibility, complexity, sensitivity, and other performance indices, it is concluded that an “all-optical” dual voltage and current contactless sensor would represent an optimum choice to be employed within remote measuring applications. The mainrecommended feature of the suggested sensor is its ability to freely measure electrical quantities while being “relatively” far from the electrical transmission line, implying no need to be “clamped” all around it. By presenting an informative background for intelligent field sensing applications, this paper also suggests the future work relevant to the studied topic.
- PublicationMetadata onlyBaseload concepts for increasing fuel cell durability in aircraft multi-powertrain operationTo increase the service life or durability of PEM fuel cells, no-load operation at open circuit voltage has to be avoided to reduce destructive electrochemical effects. This paper shows two approaches to realize a regulated base-load with a fuel cell protection unit for application in aircraft multi-powertrain-concepts. Firstly, a clocked MOSFET in the form of a chopper circuit, and secondly, a MOSFET in linear operation as current source. This contribution describes the design concept of both approaches and the validation of prototypes in a laboratory pHiL-environment. Both approaches are proven to be viable solutions, with the current source approach resulting in smoother operation.
- PublicationMetadata onlyRole of stationary energy storage systems in large-scale bus depots in the case of atypical grid usage(VDE Verlag, 2024-06-13)
; ; ; ;Soliman, RamyThe importance of electrifying buses in public transportation is increasing massively during the last few years. This owes to the health detrimental emissions of diesel buses and their effect on the climate changes. Correspondingly, the two transportation companies in Hamburg, the Hamburger Hochbahn AG and Verkehrsbetriebe Hamburg-Holstein GmbH (VHH), decided to electrify their bus depots. This ambitious goal is combined with many challenges concerning the design and operation of the charging infrastructure at the minimum costs. Among others also load management, grid impact, power quality. The aim of implementing the presented model is to search for possible usage of flexibility of electric bus depots in the energy market. This is realized by considering the bus depot as an aggregator of positive or negative flexibility. The offering of this flexibility is based on the predefined atypical grid usage in Germany. This enables electricity customers with an annual energy consumption of more than 100,000 kWh to save in grid fees for their load regulation in coordination with grid operators. Nevertheless, the operation of the bus depot has the highest priority in this study to guarantee the ability of buses to travel their routes. This paper analyses three different scenarios for atypical grid usage: the role of load management, the role of a second-life stationary battery and the combination of both cases. As a result, the required supplying periods and capacities of the stationary battery are calculated. Finally, a combined scenario between the supply from the stationary battery and the supply from the grid is presented. - PublicationMetadata onlyA multi-energy fuel cell model in the extended node methodThe coupling of the three energy grids electric power, gas and heat, via sector coupling devices such as fuel cells or electrolyzers enables the increase of the share of renewable energies in consumption beyond the electricity sector. Correct modeling is crucial for the physically correct description of the behavior of fuel cells and effects on the energy grids, especially regarding transients caused by switching processes or during plant faults. In the paper presented here, the proton exchange membrane fuel cell is introduced as a component for its use in the “Extended Node Method”. It allows a suitable integration into the grid-based energy systems electricity, gas and heat based on node equations. For this purpose, the fuel cell is described as a multi-energy component. Also, for gas and heating grids, electrical analogies are used. The associated systems of equations are constructed in such a way that they can be applied to different topologies. Exemplary operating points are shown for a sample configuration. The results are partly compared with other calculation methods and software and discussed.
- PublicationMetadata onlyImpedance-Based Method for Predictive Stability Assessment(TIB Open Publishing (Technische Informationsbibliothek), 2024-05-16)
; ;Kaiser, Sebastian ;Jordan, MichaelImpedance-based analysis methods enable a more specific and earlier foundation for assessing harmonic stability in decentralized converter-based power plants compared to the conventional compliance testing in the grid connection process. Essentially, they can be implemented as black-box model approaches without the necessity to disclose internal control models. Initially, only knowledge of the input impedances of the planned grid connection point and the planned PV system is required for application. For this purpose, the method of impedance spectroscopy for inverters has already been developed as a means to determine the effective impedance profile and the internal harmonic sources of inverters, allowing for the description of the frequency-dependent behavior of individual units. The time- and frequency-dependent grid impedance at the grid connection point (GCP) has also been successfully measured in several campaigns on medium and low-voltage grids. Through the coordinated application of both measurement methods, a predictive harmonic assessment is intended in the future, ensuring high planning reliability and grid quality even in grids with a high penetration of power electronics-coupled systems. This paper provides an overview of the current state of research on impedance-based stability criteria and presents measurement methods for practical implementation. Furthermore, it outlines remaining open questions until application in the field.