Comparative study of small-signal stability under weak AC system integration for different VSCs

Xiaojun Lu, Wang Xiang, Weixing Lin, Jinyu Wen

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Voltage source converters (VSCs) with self-commutation ability are suitable to interconnect weak AC systems. This paper conducts a comparative study of the small-signal stability characteristics for three typical VSCs, namely, the two-level VSCs (TL-VSCs), the half-bridge modular multilevel converters (HB-MMCs) and the hybrid MMCs (HY-MMCs),underweak AC system integration with special consideration on both inverter and rectifier operation. The frequency responses based on impedance models are compared using the frequency-domain analysis. The oscillation frequencies and mainly participated state variables of the unstable modes are compared using root locus and participation factor analysis in time-domain. Proper parameter retuning approaches for stability enhancement are proposed. The above analysis is adequately validated by electromagnetic simulations.
Original languageEnglish
Number of pages17
JournalIEEE Journal of Emerging and Selected Topics in Power Electronics
Early online date15 Sep 2020
Publication statusE-pub ahead of print - 15 Sep 2020


  • small signal model
  • small signal stability
  • modular multilevel converter
  • weak AC system

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