05 Fakultät Informatik, Elektrotechnik und Informationstechnik

Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/6

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Start date: 2005End date: 2005Publication Type: search.filters.UBSTyp.Abschlussarbeit (Diplom)

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    Models for transient simulations of decentral power generation : implementation and verification in PowerFactory
    (2005) Braun, Martin
    As part of the Institut für Solare Energieversorgungstechnik (ISET) e.V. in Kassel, the Design Center for Modular Supply Technology (DeMoTec) has the facilities for testing a variety of low-voltage power grid configurations. These configurations consist of decentralized power generation components in the kilowatt range. Transient simulations of components and grid configurations with MATLAB/Simulink, ATP-EMTP and SIMPLORER support research activities in this field. The aim of this work is to add a fourth tool - PowerFactory - which offers additional features for this application. All four simulation tools have their own specific characteristics which make them most suitable for particular applications. This work investigates the features of PowerFactory developed by DIgSILENT. The investigation uses components for grid configurations which are available in DeMoTec in order to verify the results of the simulations by measurements. The island grids which are investigated comprise three components: a bi-directional battery inverter which is able to form a grid, an asynchronous generator which simulates the feed-in of wind power, and a load which represents consumers and their consumption behaviour. In order to allow these components to be used in PowerFactory, this work presents the following three parts for the implementation of the components' models: 1) PowerFactory does not comprise a generic model for a battery inverter. However, single phase models in MATLAB/Simulink and ATP-EMTP are available which deliver details for the development of a PowerFactory model. For the implementation, the available models are enhanced to a three phase model and adjusted to the simulation environment of PowerFactory. 2) PowerFactory comprises a model for asynchronous generators. This generic model is adjusted to the considered asynchronous generator in DeMoTec. The electrical parameters of the analysed asynchronous generator are measured for this adjustment process and an optimisation process is performed to determine best fitting parameters. 3) A generic model for loads is available in PowerFactory. It is adjusted to correspond to the loads used in DeMoTec. The models implemented in PowerFactory form different configurations of island grids. Within these island grids, PowerFactory simulates characteristic load changes. The selected components enable measurements of the same load changes in the same grid configurations in DeMoTec. A comparison of the measured and simulated data shows a good congruence with few deviations. This thesis uses the power system analysis tool PowerFactory from DIgSILENT for transient simulations of decentralised power generation components in low-voltage grids which operate with a variable frequency and a variable voltage. Moreover, this thesis verifies the simulation results and illustrates their quality by comparing measured data at DeMoTec with simulated data using PowerFactory. Finally, one of the advantages of this simulation tool is presented by simulating a large grid configuration which is not available in the limited laboratory environment of DeMoTec.
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    Ring-Isomorphie-Probleme und das Faktorisieren großer Zahlen
    (2005) Staiger, Stefan
    Die Diplomarbeit ist eine Ausarbeitung und Weiterführung der aktuellen Forschung von Neeraj Kayal und Nitin Saxena. Diese haben das algorithmische Studium von Fragen rund um Ringe begonnen. Die Diplomarbeit präsentiert die hierbei entstandenen Algorithmen und komplexitätstheoretischen Überlegungen in ausführlicher und verständlicher Weise. Behandelt werden beispielsweise die Fragen, ob zwei Ringe isomorph sind, wie viele Automorphismen sie haben und wie man Iso- und Automorphismen berechnen kann. Hierzu werden eine Reihe mathematischer Grundlagen erläutert. Darüber hinaus leitet die Diplomarbeit neue Ergebnisse zu endlichen Ringen her und korrigiert einen Fehler von Kayal und Saxena. Ferner werden die Ring-Probleme in Beziehung gesetzt zu den bekannten Problemen der Graph-Isomorphie und des Faktorisierens großer Zahlen. Die Arbeit präsentiert außerdem einen Überblick über die aktuellen Faktorisierungsverfahren und schließt mit einer Reihe noch offener Fragen, die als Grundlage für weitere Forschung dienen können.
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    Analysing names of organic chemical compounds : from morpho-semantics to SMILES strings and classes
    (2005) Anstein, Stefanie; Kremer, Gerhard
    The linguistic analysis of chemical terminology is a key to biochemical text processing and semi-automatic database curation. The system described analyses systematic and semi-systematic names of chemical compounds, class terms, and also otherwise underspecified names by means of a morpho-semantic grammar developed according to IUPAC nomenclature. It yields an intermediate semantic representation which describes the information encoded in a name. Our tool provides SMILES strings for the mapping of names to their molecule structure and also classifies the analysed terms. It was implemented in Prolog as a prototype and a basis for further development to support research in the life sciences.