Impact of non-minimum-phase zeros on the weak-grid-tied VSC

Guanglu Wu, Bing Zhao, Xi Zhang, Shanshan Wang, Agusti Egea-Àlvarez, Yuany uan Sun, Yingbiao Li, Deyang Guo, Xiaoxin Zhou

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12 Citations (Scopus)
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Right-half-plain (RHP) zeros can significantly deteriorate a control system’s dynamic performances as it exhibits non-minimum-phase behaviors. In this paper, we investigate the occurrence mechanism of RHP zeros in weak-grid-tied VSCs as well as provide guidance for minimizing their effects. A reduced order multi-input multi-output (MIMO) transfer function of the weak-grid-tied VSC is firstly obtained. Then, the single-input single-output (SISO) transfer function to study the impact of the RHP zeros on the power response is further derived. The existence of RHP zeros is examined by applying the Routh criterion on the numerator of the SISO open-loop transfer function. We find that RHP zeros can exist either when the VSC works as an inverter or a rectifier. Furthermore, large grid impedance values as well as operation points with high active power values can result in a non-minimum-phase system. It is also shown that RHP zeros limit the minimum PLL bandwidth. Simulation results and RTDS experiments validate the correctness of the analysis and the conclusions obtained.
Original languageEnglish
Number of pages11
JournalIEEE Transactions on Sustainable Energy
Early online date29 Oct 2020
Publication statusE-pub ahead of print - 29 Oct 2020


  • weak grid tied VSC
  • non-minimum phate zeros
  • MIMO transfer function
  • small signal model
  • controller bandwidth


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