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Dynamic Phasor Modeling of Modular Multilevel Converters for Hybrid AC/DC Power Systems

  • Author / Creator
    Rojas Tarango, Abraham
  • This thesis develops a time averaged model (TAM) and a dynamic phasor model (DPM) of a generalised modular multilevel converter (MMC) structure that can be used to represent four different MMC topologies. These four topologies include two different classes of next generation MMCs that are garnering attention for use in hybrid AC/DC power systems: (i) DC/DC/AC MMCs that combine DC/DC and AC/DC conversion stages into a single converter structure, and (ii) DC/DC MMCs. The former enables controlled power exchange between two DC systems and an AC grid while the latter is a key building block of future DC grids. A TAM is developed in the __0 frame that includes all dynamics in a converter, barring switching harmonics. This model is useful when detailed studies of the converter dynamics are required, but the long simulation time of the switched model is an impediment. A DPM is then derived from the TAM that takes into account multiple harmonic components to ensure an accurate representation of the practical converter behaviour across a wide range of operating points. This model permits the elaboration of a steady-state solution procedure to solve for the full state solution at an arbitrary operating point, enabling systematic study of the DC/DC/AC and DC/DC MMCs using industry standard numerical software tools. Extensive simulations and steady-state analyses are carried out to investigate the converters’ behaviour, including how the current stresses and capacitor voltage ripples change due to varying parameters such as DC and AC systems power flows.

  • Subjects / Keywords
  • Graduation date
    Fall 2020
  • Type of Item
    Thesis
  • Degree
    Master of Science
  • DOI
    https://doi.org/10.7939/r3-y5cg-7t16
  • License
    Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.