Now showing 1 - 2 of 2
  • Publication
    Autonomous Current Sharing Control with Integrated Virtual Impedance and Self Synchronisation for Unbalanced Islanded Microgrids
    ( 2020-10-11) ;
    Holmes D.G.
    ;
    McGrath B.P.
    This paper proposes a new autonomous current sharing control strategy for islanded microgrids that is simple and robust under unbalanced load conditions. The strategy estimates the distributed generator output voltage and current positive sequence components from the internal variables of a resonant current and resonant voltage regulator, and then uses them to create an integrated virtual impedance sharing mechanism. This avoids control complexity and the need for output current measurements, while maintaining a balanced voltage and accurate current sharing. The approach has been verified using a detailed switched simulation.
  • Publication
    Virtual flux-based grid-forming current controller for flexible operation of voltage source converters
    (Institute of Electrical and Electronics Engineers Inc, 2022-01-01) ;
    Holmes D.G.
    ;
    McGrath B.P.
    This paper presents a novel approach to incorporate a grid forming capability into a grid-following voltage source converter, while maintaining the high-bandwidth current control capability that is typical of such a converter. The approach uses the resonator outputs of a stationary frame current regulator as a virtual flux estimation of the converter output voltage, and integrates this estimation into an electrical model of a virtual synchronous generator without requiring integration and derivative operations. The generator and converter models are then combined to achieve a robust grid-forming response under grid islanding conditions, without requiring direct grid-side voltage measurements. The proposed strategy is validated using a detailed switching simulation model of the converter and its control processes.
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