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In the frame of this thesis, unintended interruptions of electric vehicle charging processes were detected while the power quality was within normative limits. This indicates that poor power quality could impose a significant risk for the successful integration of electric vehicles into the distribution grids. Particularly higher frequency harmonics in the range from 2 to 150 kHz (Supraharmonics), generated by modern power electronic applications, raise concerns among the scientific and standard setting communities. There is limited knowledge and experience about the long-term behavior of Supraharmonics in the field. The main reasons are the lack of suitable measurement equipment and data analysis methods, able to overcome the challenge of processing the large amounts of generated data in an efficient manner. This work proposes a new monitoring approach for the continuous long-term measurement and characterization of Supraharmonics, which are rarely measured in the field.
The stability of power systems and microgrids is compromised by the increasing penetration with power electronic devices, such as wind turbines, photovoltaics and batteries. A simulation and optimization environment for such low-inertia systems is created. It is investigated how accurate the models need to be to capture the prevailing modes. An evolutionary algorithm tailored to optimization problems with computationally intensive fitness evaluation is proposed in order to optimized the controller parameters of grid-forming and grid-supporting distributed generators. It becomes apparent that microgrids dominated by grid-forming inverters are very stable systems when well-designed and optimized controllers are used. Model simplifications, such as the neglect of inner control loops of inverters, must be examined carefully, as they can lead to an inaccurate stability assessment.
This thesis introduces a fully data driven approach for the prediction and optimization of critical electrical grid states due to poor power quality. Therefore, a nonvolatile memory model for time series forecasting, designed to profit especially from big data bases and complex pattern use cases as well as an Artificial Intelligence based Smart Demand Side Management framework to enable system inherent resources / components for minimization of harmonic disturbances is applied to measured power grid scenarios.
In dieser Arbeit wird ein praxistaugliches Konzept für einen aktiven Verteilnetzbetrieb vorgestellt sowie dessen Implementierung in einem realen deutschen Niederspannungsnetz beschrieben. Gegenstand der Untersuchungen ist dabei die komplette Prozesskette eines automatisierten Niederspannungsnetzbetriebs, angefangen bei der Kommunikationsanbindung, über die Bestimmung des aktuellen Netzzustands in Echtzeit, als Basis für einen sicheren Betrieb, bis hin zur letztlichen Flexibilitätsnutzung. Durch eine abschließende Demonstration der entwickelten Konzepte und Methoden im Rahmen von Feldversuchen während des regulären Niederspannungsnetzbetriebs, werden diese unter Realbedingungen validiert. Es kann gezeigt werden, dass eine großflächige Umsetzung des beschriebenen Konzepts praktikabel ist, wodurch perspektivisch eine Spannungsebenen übergreifende Bereitstellung von Flexibilität aus den Verteilnetzen ermöglicht werden kann, wenngleich der Investitionsbedarf dem gegenübersteht.
Diese Arbeit entwickelt ein praktikables und übertragbares Konzept einer Verteilnetz- Zustandsschätzung für den Einsatz in Mittel- und Niederspannungsnetzen. Die Erweiterung ausgewählter Zustandsschätzalgorithmen erfolgt dabei mit dem Fokus der Anwendung unter realen Rahmenbedingungen, als auch in Bezug auf eine spannungsebenenübergreifende Berechnung des Systemzustandes. Das entwickelte Verfahren zur Generierung anpassbarer Pseudomesswerte eignet sich sowohl für die Nachbildung einzelner als auch aggregierter Verbraucher und Erzeuger. Der Konzeptnachweis der vorgestellten Methode in Bezug auf die Bewertung der Schätzgüte, findet in zwei realen Mittelspannungsnetzen statt.
This exhaustive reference includes new chapters and pedagogical features, as well as—for the first time—content on managing fragility factures. To facilitate fast, easy absorption of the material, this edition has been streamlined and now includes more tables, charts, and treatment algorithms than ever before. Experts in their field share their experiences and offer insights and guidance on the latest technical developments for common orthopaedic procedures, including their preferred treatment options.
In the last third of the nineteenth century, the discourse on the “Jewish question” in the Habsburg crownlands of Galicia changed fundamentally, as clerical and populist politicians emerged to denounce the Jewish assimilation and citizenship. This pioneering study investigates the interaction of agitation, violence, and politics against Jews on the periphery of the Danube monarchy. In its comprehensive analysis of the functions and limitations of propaganda, rumors, and mass media, it shows just how significant antisemitism was to the politics of coexistence among Christians and Jews on the eve of the Great War.
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