Charakterisierung der Leistungselektronik für die elektrische Netzkopplung eines SOFC Systems

Translated title of the contribution: Characterization of the power electronics for the electrical grid coupling of a SOFC system

Philipp Prikoschnig

Research output: ThesisMaster's Thesis

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Abstract

In the future, the world’s population will need more and more energy for its “energy wealth”. In order to reach the ambitious goals of reducing CO2 emissions as well as to satisfy growing global energy demand, an increasing amount of renewable energy production is necessary. As energy gained from renewable sources is highly dependent on weather, seasons and other influences, there the demand cannot be covered by the renewable production only. Thus there is still a dependence on fossil fuels, but they should be used as efficiently as possible. Fuel cells (SOFC systems) on the one hand are highly flexible and on the other hand also able to run on both natural gas and hydrogen which may be produced out of renewable sources. This work, focuses on supplying the electrical power generated by a functioning 5 kW SOFC system into the electrical grid. In the first step, this formulation appears to be banal, since photovoltaic systems in this performance range are already commonly coupled to the electrical grid. However, due to the different operational parameters of the SOFC system, in which the system produces a very high current at a very low voltage, conventional PV inverters cannot be used for integration into the electrical grid without additional measures. Most inverters cannot operate their full power at this low voltage level. Therefore, it is necessary to find a suitable DC/DC converter which ideally fits to the parameters of the SOFC system and the inverter. By adjusting the parameters of the SOFC system, it is possible to use a conventional photovoltaic inverter for the electric supply. However, this concept is intended to work very efficiently and dynamically to generate minimal loss during the electric supply. Furthermore, it is important that the system is able to deliver high voltage and current quality to the grid as well as not to generate any harmonics. Once the basic structure of the feed-in concept has been designed, the overall system has to be created for the optimum operation of the internal supply units. In addition to a very efficient use of the available energy, the possibility of an isolated operation will be investigated. Regarding these restrictions, different concepts were compared and analyzed on possible operating strategies. This indicates that there are limitations in the range of maximum output power, which leads to a limited number of operating modes. Due to those restrictions, several solutions are developed and presented within this thesis. The concepts can either increase the degree of self-sufficiency of the plant or constantly feed more than 5 kW of electrical power into the grid.
Translated title of the contributionCharacterization of the power electronics for the electrical grid coupling of a SOFC system
Original languageGerman
QualificationDipl.-Ing.
Awarding Institution
  • Montanuniversität
Supervisors/Advisors
  • Böckl, Benjamin, Co-Supervisor (internal)
  • Hauth, Martin, Supervisor (external), External person
  • Kienberger, Thomas, Supervisor (internal)
Award date29 Jun 2018
DOIs
Publication statusPublished - 2018

Bibliographical note

embargoed until 19-06-2023

Keywords

  • Fuel cell
  • SOFC
  • Inverter
  • Boost converter
  • Electrical feed

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