Impedance-Based Prediction of SSR-Generated Harmonics in Doubly-Fed Induction Generators

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8 Scopus Citations


Doubly-fed induction generators (DFIGs) are prone to subsynchronous resonance (SSR) with series-compensated transmission lines and experiencing SSR-generated harmonics of wide-ranging magnitudes. This paper presents a large-signal impedance-based approach for the prediction of the magnitude of SSR-generated harmonics in DFIGs. Note that the large-signal impedance of a network shows variation in its impedance response with the magnitude of perturbation at its terminals. It is discovered in this paper that the impedance of a series-compen- sated transmission line starts changing with the magnitude of SSR because of the metal-oxide varistor-based protection of series capacitors in the line. The changing line impedance halts the growth of the SSR beyond a certain point, where the DFIG forms a limit-cycle mode and emits harmonics at the SSR frequency. The discovered role of the protection of series capacitors in SSR not only enables the prediction of SSR-generated harmonics but also can be used for the timely detection of an SSR event to avoid system disruption and sudden loss of bulk generation. The large- signal impedance-based prediction of SSR-generated harmonics in DFIG-based wind and hydro generators is demonstrated using numerical simulations of a 2.5-MVA, 690-V DFIG supplying to a series-compensated transmission line.

Original languageAmerican English
Number of pages5
StatePublished - Aug 2019
Event2019 IEEE Power and Energy Society General Meeting, PESGM 2019 - Atlanta, United States
Duration: 4 Aug 20198 Aug 2019


Conference2019 IEEE Power and Energy Society General Meeting, PESGM 2019
Country/TerritoryUnited States

Bibliographical note

See NREL/CP-5D00-72559 for preprint

NREL Publication Number

  • NREL/CP-5D00-76219


  • DFIG
  • hydro generators
  • impedance analysis
  • MOV
  • series-compensated transmission lines
  • SSR
  • wind turbines


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