Between Dec 19, 2024 and Jan 2, 2025, datasets can be submitted to DRUM but will not be processed until after the break. Staff will not be available to answer email during this period, and will not be able to provide DOIs until after Jan 2. If you are in need of a DOI during this period, consider Dryad or OpenICPSR. Submission responses to the UDC may also be delayed during this time.

Browsing by Subject "HVDC"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Control strategies of MMC-HVDC connected to large offshore wind farms for improving fault ride-through capability
    (2020-07) Choi, Woojung
    This paper proposes strategies to improve fault ride-through (FRT) capability of the modular multi-level converter (MMC) - high voltage direct current (HVDC) system connected to large offshore wind farms and performs simulations. In offshore wind power plants, HVDC system is indispensable for long-distance high-capacity transmission. The voltage rise of HVDC-link happens inevitably due to energy accumulation to satisfy low voltage ride-through (LVRT) regulation when a main grid fault occurs. This paper presents strategies for controlling HVDC-link voltages while minimizing the application of DC choppers and the mechanical and electrical stress of wind turbines through fast fault detection and current limit control of the master controller and wind turbine converter. PSCAD/EMTDC simulation is performed to verify the control strategies, and the results show that the FRT capability is enhanced by controlling HVDC-link voltage properly.
  • Thumbnail Image
    Item
    Modulation, Control and Performance Analysis of Asymmetrical Modular Multilevel Converters (A-MMCs)
    (2017-02) Srivastav, Kundan
    Modular multilevel converters (MMCs) are preferred converters for implementing high-power multilevel systems. The penalty they impose is the high number of devices needed to build them. To offset this challenge, this thesis introduces Asymmetrical Modular Multilevel Converters (A-MMCs). Unlike MMCs, each A-MMC module comprises of two half-bridge submodules, rated at asymmetric voltages. This system offers benefits like: (a) generation of four distinct voltage levels using one module; (b) 33% lesser semiconductor and gate drive requirement; (c) higher system efficiency; (d) reduction in overall cost and size. Hybrid Pulse-Width Modulation (Hybrid PWM) has been deployed to generate the drive pulses. To maintain asymmetric voltages, a novel voltage balancing algorithm has been proposed. Circulating current controller has been designed as well. The operation and performance validation was done using MATLAB Simulink and PLECS Blockset. A comparison, vis-`a-vis the MMC, was also performed, based on thermal performance and essential circuit voltages and currents.