Power differential method for discrimination between fault and magnetizing inrush current in transformers

Research output: Contribution to journalArticlepeer-review

170 Citations (Scopus)

Abstract

To avoid the needless trip by magnetizing inrush current, the second harmonic component is commonly used for blocking differential relay in power transformers. However, the second harmonic component in fault current is increased by the introduction of underground 500kV lines. This paper describes a new method to discriminate internal fault from inrush current by the sum of active power flowing into transformers from each terminal. The average power is almost zero for energizing, but an internal fault consumes large power. To check the performance of this method, actual inrush current and voltage waveforms of 500/154kV transformer are accurately measured by digital equipment. The usefulness is confirmed by applying the method to the measured inrush and simulated fault data.

Original languageEnglish
Pages (from-to)1109-1115
Number of pages7
JournalIEEE Transactions on Power Delivery
Volume12
Issue number3
DOIs
Publication statusPublished - 1997
Externally publishedYes

Keywords

  • Active power relays
  • Magnetizing inrush
  • Microprocessor-based relays
  • Protection relays
  • Transformer protection

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering

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