Analysis of Middle Frequency Resonance in DFIG System Considering Phase Locked Loop

Yipeng Song, Frede Blaabjerg

Research output: Contribution to journalJournal articleResearchpeer-review

24 Citations (Scopus)
367 Downloads (Pure)


As the wind power technology develops, the Doubly Fed Induction Generator (DFIG) based wind power system, when connected to a weak network with large impedance, may suffer resonances, i.e., Sub- Synchronous Resonance (SSR) or High Frequency Resonance (HFR) when connected to the series or parallel compensated weak network. Besides these two resonances, a Middle Frequency Resonance (MFR) between 200 Hz and 800 Hz may appear when the Phase Locked Loop (PLL) with fast control dynamics is applied. In order to analyze the MFR, the DFIG system impedance considering the PLL is studied based on the Vector Oriented Control (VOC) strategy in Rotor Side Converter (RSC) and Grid Side Converter (GSC). On the basis of the established impedance modeling of the DFIG system, it is found that the PLL with fast control dynamics may result in the occurrence of MFR due to a decreasing phase margin. The simulation results of both a 7.5 kW small scale DFIG system and a 2 MW large scale DFIG system are provided to validate the theoretical analysis of the MFR.
Original languageEnglish
Article number7862270
JournalI E E E Transactions on Power Electronics
Issue number1
Pages (from-to)343-356
Number of pages14
Publication statusPublished - Jan 2018


  • Controller parameters
  • Doubly fed induction generator (DFIG) system
  • Middle frequency resonance (MFR)
  • Phase-locked loop (PLL)
  • Parallel-compensated weak network parallel-compensated weak network
  • doubly fed induction generator (DFIG) system
  • parallel-compensated weak network
  • middle frequency resonance (MFR)
  • phase-locked loop (PLL)

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