Large-Signal Impedance-Based Modeling and Mitigation of Resonance of Converter-Grid Systems

Shahil Shah, Przemyslaw Koralewicz, Vahan Gevorgian, Robert Wallen, Kapil Jha, Dale Mashtare, Rajni Burra, Leila Parsa

Research output: Contribution to journalArticlepeer-review

48 Scopus Citations


Large-signal impedance of grid-connected converters can be used to predict resonance-generated distortions in converter-grid systems. Note that the large-signal impedance of a network represents its impedance response for different magnitudes of perturbation injected at its terminals. This paper presents large-signal impedance-based modeling and mitigation of resonance of grid-connected voltage source converters. Challenges of large-signal modeling because of the inapplicability of the small-signal approximation are addressed by leveraging the dominating influence of hard nonlinearities (such as pulsewidth modulation saturation and limiters) over soft nonlinearities (such as Park's transformations and phase-locked loop (PLL)) in shaping the large-signal behavior of the converter. The paper develops large-signal gains of hard nonlinearities using different types of describing functions. The paper shows that the large-signal impedance of a voltage source converter (VSC) can be shaped to reduce resonance-generated distortions by inserting limiters in the control system of the VSC. Developed large-signal impedance models are validated using numerical simulations of a VSC with dq current control and PLL. Large-signal impedance measurements of a commercial 1 MW VSC-based inverter and a medium-voltage doubly-fed induction generator with approximate 4 MW rating are presented to experimentally demonstrate the influence of the injected perturbation magnitude on the impedance response.

Original languageAmerican English
Article number8662593
Pages (from-to)1439-1449
Number of pages11
JournalIEEE Transactions on Sustainable Energy
Issue number3
StatePublished - Jul 2019

Bibliographical note

Publisher Copyright:
© 2010-2012 IEEE.

NREL Publication Number

  • NREL/JA-5D00-71935


  • impedance analysis
  • Large-signal modeling
  • resonance
  • voltage source converters
  • wind power-plant stability


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