Journal of Power Electronics

The Korean Institute of Power Electronics (전력전자학회)
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DC-side admittance model of converters with constant power control considering DC-side voltage fuctuation

  • Xin Tang (School of Electrical and Information Engineering, Changsha University of Science and Technology) ;
  • Zhen Li (School of Electrical and Information Engineering, Changsha University of Science and Technology) ;
  • Yang He (School of Electrical and Information Engineering, Changsha University of Science and Technology) ;
  • Liyang Wang (School of Electrical and Information Engineering, Changsha University of Science and Technology) ;
  • Yufei Yue (School of Electrical and Information Engineering, Changsha University of Science and Technology) ;
  • Wen Wang (School of Electrical and Information Engineering, Changsha University of Science and Technology)
  • Received : 2021.11.28
  • Accepted : 2022.09.19
  • Published : 2023.02.20
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Abstract

In the stability analysis of DC (direct-current) power grids, AC (alternating current)/DC converters are usually treated as linear proportional amplifiers or inertial links. However, this approximation will have a considerable effect on the DC-side impedance model of a constant active power control converter and then affect the accuracy of the stability analysis of DC grids. In this paper, in view of the DC-side of the voltage fluctuations, the DC-side admittance model is established after the nonlinear relationship between the port voltage and the modulation signal function is determined. A comparison is made between the traditional modeling method and the proposed modeling method in the analysis of the phase-frequency characteristics and amplitude-frequency characteristics of the admittance. Results show that the proposed small-signal model can better fit the measured admittance in the low-frequency bands. The proposed admittance model in this paper is further applied to assess the small-signal stability of a DC grid. Finally, PSCAD/EMTDC simulation and lab-scaled prototype experiment are used to verify the correctness and effectiveness of the established admittance model. Results show that the small-signal model deduced in this paper can better fit and measure the admittance in the low-frequency band, and can more accurately judge the stability of the DC system.

Keywords

Acknowledgement

This work was partially supported by the National Natural Science Foundation of China (51977013) and the Hunan Provincial Natural Science Foundation of China (2021JJ40605).

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