Analysis and comparison of high frequency resonance in small and large scale DFIG system

When connected to a parallel compensated weak grid network, both the small and large power scale Doubly Fed Induction Generator (DFIG) system may suffer high frequency resonance (HFR) due to the impedance interaction between the DFIG system and the parallel compensated weak network. Since the parameters of the small and large scale DFIG systems, including DFIG machine parameters and the LCL filter parameters, may vary between 10 to 100 times, the impedance modeling results of small and large scale DFIG system are quite different. Based on the built impedance modeling results, the HFR in small and large scale DFIG system are theoretically analyzed and compared in this paper with the discussion on the influence of PI controller proportional parameters and the digital control delay on the DFIG system impedance shaping. The experimental validation of small scale DFIG system and the simulation validation of large scale DFIG system are conducted to verify the correctness of the analysis.