A Current-Based Differential Technique to Detect Loss of Field in Synchronous Generators

Abbas Hasani, Farhad Haghjoo*, Filipe Miguel Faria Da Silva, Claus Leth Bak

*Corresponding author

Research output: Contribution to journalJournal articleResearchpeer-review

8 Citations (Scopus)


A new approach for generator loss of field (LOF) protection is proposed by estimating the field current based on the generator measurable parameters. The main idea of the proposed approach is that a significant difference will be created between the measured excitation and the estimated field currents during LOF occurrence. A differential index is introduced to monitor such difference and consequently to detect LOF failures. A detailed and realistic field circuit is considered for the generator by using the phase-domain model of the generator in the real-time digital simulator, while different types of LOF events can be simulated through such model as well. The obtained results show that the presented technique can detect various types of LOF events much faster than the conventional impedance-based scheme. Moreover, it exhibits more security than the conventional technique in the face of power system disturbances (e.g., stable power swing and out-of-step conditions).
Original languageEnglish
Article number8686237
JournalIEEE Transactions on Power Delivery
Issue number2
Pages (from-to)514-522
Number of pages9
Publication statusPublished - Apr 2020


  • loss of field detection
  • out of step
  • real-time-digital-simulator
  • stable power swing
  • Synchronous generator


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