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Adaptive Virtual Impedance of Grid-Tied Inverters to Enhance the Stability in a Weak Grid

  • Yan Du
  • Qingqing Sun
  • Xiangzhen YangEmail author
  • Linbo Cui
  • Jian Zhang
  • Fei Wang
Original Article
  • 21 Downloads

Abstract

In a weak grid, especially with a grid-voltage proportional feedforward controller, the grid-tied inverter tends to interact with the grid impedance and thus suffers from poor power quality and even instability. In order to improve the stability, serial-parallel virtual impedance based on the derivative controllers of grid current and voltage is proposed in this paper. With the aim of optimizing the performance of the inverter for a variety of grid impedance, these derivative coefficients are adaptively tuned by the constraint of a minimum leading phase which is determined by the phase margin and the current tracking response. With this proposed adaptive virtual impedance, the grid-tied inverter can operate stably under a wide variety of grid impedance and voltage harmonic rejection performance is also improved. Simulation and experimental results validate the effectiveness of the proposed method and design methodology.

Keywords

Adaptive control Grid-voltage feedforward Grid-tied inverters Weak grid 

Notes

Acknowledgements

This work was supported by the KIEE.

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Copyright information

© The Korean Institute of Electrical Engineers 2019

Authors and Affiliations

  • Yan Du
    • 1
  • Qingqing Sun
    • 1
  • Xiangzhen Yang
    • 1
    Email author
  • Linbo Cui
    • 1
  • Jian Zhang
    • 1
  • Fei Wang
    • 2
  1. 1.Department of Electrical Engineering and AutomationHefei University of TechnologyHefeiChina
  2. 2.Department of Electrical Engineering and AutomationShanghai UniversityShanghaiChina

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