Absolute Stability Improvement of Grid-Following Inverters: A Grid-Impedance-Detection-Based Current Compensation Control Method

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Abstract
The strict absolute stability analysis of the overall grid-following inverter (GFLI) system can be achieved by adopting the orthogonal-normalization-based grid synchronizer (ONGS), but the system robustness is limited by the weak grid, injected power and port voltage level. To improve the absolute stability, this paper proposes a novel grid impedance detection and current adaptive compensation-based ONGS (IDCAC-ONGS), which introduces the grid current feedback signal into the synchronizer input. Based on the absolute stability criteria of the GFLI system composed of synchronous nonlinear criterion and traditional impedance criterion, the reason why the proposed current-compensation-based ONGS (CC-ONGS) has better robustness than the conventional ONGS is explained. Compared with CC-ONGS, a harmonic-injection-based grid impedance detection unit is embedded in proposed IDCAC-ONGS, which can select proper compensation coefficient to further improve the absolute stability. Finally, theoretical analysis and experimental results verify the effectiveness of proposed control strategies.
Funding Information
  • National Natural Science Foundation of China (52277183)
  • National Natural Science Foundation of China (52407212)
  • National Natural Science Foundation of China (52277184)
  • Natural Science Foundation of Shandong Province (ZR2024QE066)
  • China Postdoctoral Science Foundation (2024M751807)
  • Postdoctoral Fellowship Program of China Postdoctoral Science Foundation (GZC20240908)

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