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Visar resultat 21 - 25 av 25 avhandlingar som matchar ovanstående sökkriterier.

  1. 21. Grid Connection of Permanent Magnet Generator Based Renewable Energy Systems

    Författare :Senad Apelfröjd; Sandra Eriksson; Frans Dijkhuizen; Uppsala universitet; []
    Nyckelord :VAWT; H-rotor; Tap Transformer; Cascaded H-bridge Multi-Level; Renewable Energy; Wind power; Wave power; Marine Current Power; Engineering Science with specialization in Science of Electricity; Teknisk fysik med inriktning mot elektricitetslära;

    Sammanfattning : Renewable energy is harnessed from continuously replenishing natural processes. Some commonly known are sunlight, water, wind, tides, geothermal heat and various forms of biomass. The focus on renewable energy has over the past few decades intensified greatly. LÄS MER

  3. 22. Wind Farm Configuration and Energy Efficiency Studies - Series DC versus AC Layouts

    Författare :Stefan Lundberg; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

    Sammanfattning : In this thesis, the design and control of a wind farm utilizing series-connected wind turbines with a DC output has been evaluated. The advantage is that a suitable DC voltage level, appropriate for transmission of the generated power directly, without using a large centralized DC/DC converter, can be obtained. LÄS MER

  4. 23. On stability of vortices and vorticity generated by actuator lines

    Författare :Vitor Gabriel Kleine; Dan S. Henningson; Ardeshir Hanifi; Stéphane Le Dizès; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Teknisk mekanik; Engineering Mechanics;

    Sammanfattning : Vortices are present in nature and in many flows of industrial importance. The stability of configurations of vortices can have real-world consequences, because vortices play a crucial role in accelerated mixing. In particular, vortices are present in the wake of wind turbines and other rotors. LÄS MER

  5. 24. Medium Voltage Generation System with Five-level NPC Converters for Kite Tidal Power

    Författare :Georgios Mademlis; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Voltage balancing; Maximum Power Point Tracking MPPT ; Medium Voltage Converters; Multilevel Space-Vector-Modulation; Neutral point clamped converter NPC ; Subsea kite; Tidal power;

    Sammanfattning : Offshore power generation has emerged as a prominent source of energy and the installed capacity of new plants has been steadily increasing in recent years. Tidal power specifically is a promising renewable energy source which has not been highly exploited yet, despite its distinctive advantages of being predictable and independent of weather conditions. LÄS MER

  7. 25. Multilevel three-phase dual active bridge dc-dc converters - A study on converter modulation, capacitive energy requirement, ZVS boundaries, MFT's winding connections, and core losses

    Författare :Babak Alikhanzadehalamdari; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; high-voltage power converters; dual active bridge; harmonic analysis; three-phase system; medium-frequency transformer; capacitor sizing; multilevel converters; high power-density systems; transformer winding connection; core loss modeling; dc collector network; soft-switching converters;

    Sammanfattning : The collection and transmission of power from offshore wind turbines using dc have advantages over the ac system. One of the enabling technologies for deploying dc collection is the dc-dc converter that boosts the dc output from the turbine to the medium-voltage dc level of the collection grid. LÄS MER