Proceedings of the KIPE Conference (전력전자학회:학술대회논문집)

The Korean Institute of Power Electronics (전력전자학회)
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Control of Circulating Current in Modular Multilevel Converter under Unbalanced Voltage using Proportional-Resonant Controller

  • Quach, Ngoc-Thinh (Department of Electrical Engineering, Jeju National University) ;
  • Chae, Sang Heon (Department of Electrical Engineering, Jeju National University) ;
  • Kim, Eel-Hwan (Department of Electrical Engineering, Jeju National University)
  • Published : 2016.11.25
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Abstract

The circulating current control within the phase legs is one of the main control objectives in a modular multilevel converter (MMC) under different operating conditions. This paper proposes a control strategy of circulating currents in the MMC under unbalanced voltage by using a proportional-resonant (PR) controller. Under the unbalanced voltage, the circulating currents in the MMC consists of three components such as positive-sequence, negative-sequence, and zero-sequence circulating currents. With the PR controller, all components of the circulating current will be directly controlled in the stationary reference frame without decomposing into positive- and negative-sequence components. Thus, the ripples in the circulating currents and the DC current are suppressed under the unbalanced voltage. The effectiveness of the proposed method is verified by simulation results based on PSCAD/EMTDC simulation program.

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