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


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.


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



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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