Robust Two Degrees-of-freedom Single-current Control Strategy for LCL-type Grid-Connected DG System under Grid-Frequency Fluctuation and Grid-impedance Variation

Leming Zhou, Yandong Chen, An Luo, Josep M. Guerrero, Xiaoping Zhou, Zhiyong Chen, Wenhua Wu

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36 Citations (Scopus)
322 Downloads (Pure)

Abstract

For LCL-type grid-connected distributed generation(DG) system, the grid-frequency fluctuation and grid-impedance variation affect the active/reactive power control accuracy and resonance peak suppression respectively, which would reduce the system robustness. In this paper, a robust two degrees-of-freedom single-current control (RTDOF-SCC) strategy is proposed, which mainly includes the synchronous reference frame quasi-proportional-integral (SRFQPI) control and robust grid-current-feedback active damping (RGCFAD) control. The proposed SRFQPI control can compensate the local-loads reactive power, and regulate the instantaneous grid current without steady-state error regardless of the fundamental frequency fluctuation. Simultaneously, the proposed RGCFAD control effectively damps the LCL-resonance peak regardless of the grid-impedance variation, and further improves both transient and steady-state performances. The stability margin and dynamic response of the overall system are analyzed in detail, and the proper parameters are selected without complicated trial. Finally, Simulation and experimental results verify the proposed control and design strategies.
Original languageEnglish
JournalIET Power Electronics
Volume9
Issue number14
Pages (from-to)2682 - 2691
Number of pages10
ISSN1755-4535
DOIs
Publication statusPublished - Nov 2016

Keywords

  • Grid-connected inverter
  • Active damping
  • Single-current control
  • Two degrees-of-freedom
  • LCL-filter

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