The assembly of this study started in 2013 during the preparation of the foundation of the Flexible Electrical Networks (FEN) Research Campus, an institution supported by the German Federal Ministry of Education and Science, concentrating on DC technology in power grids as an enabler for the energy transition. It reflects the state-of-the-art and research needs of DC technology against the background of application in public grids up until the year 2015. Topics as components, control, management and automation, high-, medium, and low-voltage grid concepts as well as social dimensions, economics, and impact on living beings are considered. After substantial editorial effort, its first public edition has become ready now. The aim of FEN is to investigate and to develop flexible power grids. Such grid will safeguard the future energy supply with a high share of fluctuating and decentralized renewable energy sources. At the same time, these grids will enable a reliable and affordable energy supply in the future. The objective is to provide new technologies and concepts for the security and quality of the energy supply in the transmission and distribution grids. To pursue this goal, the use of direct-current (DC) technology, based on power electronics, automation and communication technologies, plays an important role. Although DC technology is not yet established as a standard technology in the public electrical power supply system, its high potential has been widely recognized. The use of DC is an enabler to make the future energy supply system more economical than a system based on alternating-current (AC), because of its superior properties in handling distributed and fluctuation power generation. Indeed, DC connections are already the most cost-efficient solution in cases of very high-power long-distance point-to-point transmission of electricity or via submarine cables. The objective of the FEN Research Campus is now to achieve and demonstrate feasibility of DC as a standard solution for future electrical grids, as described in this study.
The assembly of this study started in 2013 during the preparation of the foundation of the Flexible Electrical Networks (FEN) Research Campus, an institution supported by the German Federal Ministry of Education and Science, concentrating on DC technology in power grids as an enabler for the energy transition. It reflects the state-of-the-art and research needs of DC technology against the background of application in public grids up until the year 2015. Topics as components, control, management and automation, high-, medium, and low-voltage grid concepts as well as social dimensions, economics, and impact on living beings are considered. After substantial editorial effort, its first public edition has become ready now. The aim of FEN is to investigate and to develop flexible power grids. Such grid will safeguard the future energy supply with a high share of fluctuating and decentralized renewable energy sources. At the same time, these grids will enable a reliable and affordable energy supply in the future. The objective is to provide new technologies and concepts for the security and quality of the energy supply in the transmission and distribution grids. To pursue this goal, the use of direct-current (DC) technology, based on power electronics, automation and communication technologies, plays an important role. Although DC technology is not yet established as a standard technology in the public electrical power supply system, its high potential has been widely recognized. The use of DC is an enabler to make the future energy supply system more economical than a system based on alternating-current (AC), because of its superior properties in handling distributed and fluctuation power generation. Indeed, DC connections are already the most cost-efficient solution in cases of very high-power long-distance point-to-point transmission of electricity or via submarine cables. The objective of the FEN Research Campus is now to achieve and demonstrate feasibility of DC as a standard solution for future electrical grids, as described in this study.
Diese Studie führt eine Auslegung von supraleitenden Kabeln für die Anwendung im 380-kV-Drehstromnetz durch und erläutert allgemeine Aspekte des Einsatzes solcher Kabel im Höchstspannungsnetz. Dabei vergleicht sie die Supraleitungstechnologie unter vielen verschiedenen Kriterien mit anderen Leitungstechnologien. - This study describes the design of superconducting cables for use in the 380 kV three-phase network and explains general aspects of the use of such cables in the extra-high voltage grid. It compares the superconducting technology with other line technologies under many different criteria.
Copepods are among the most abundant multicellular organisms in the world. Despite their central role in all aquatic habitats ranging from the deep ocean to the glaciers, surprisingly little is known about their population dynamics under environmental changes. This thesis provides novel insights in the response of freshwater copepods to declining nutrient concentrations and climate variability with a primary focus on the role of seasonality, life cycle strategy, and stage-structured interactions. The first and second chapter analysed in detail the responses of two single copepod species with a simple and a complex life cycle, respectively. In the third chapter the mutual relationships of all species was investigated with an emphasis on the role of their evolved life cycle strategies. These results were compared to four other locations in chapter four. This thesis clearly shows that the whole annual life cycle and the seasonality of both juveniles and adults must be taken into account to gain a mechanistic understanding of species responses to environmental change. This knowledge is elementary to predict potential influences of future environmental changes such climate change.
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