The Advanced Protection Coordination Scheme using Phase Angle of Zero-Sequence Current in Ungrounded System

비접지 계통에서 영상전류 위상을 이용한 개선된 보호협조 방안

  • 최영준 ((주)효성 중공업연구소) ;
  • 임희택 (한전 KDN 전력IT연구원, 배전IT그룹) ;
  • 최면송 (명지대 공대 전기공학과) ;
  • 이승재 (명지대 공대 전기공학과)
  • Published : 2010.01.01


Most faults are single-phase-to-ground fault in ungrounded system. The fault currents of single-phase-to-ground are much smaller than detection thresholds of measurement devices, so detecting single-phase-to-ground faults is difficult and important in ungrounded system. The protection coordination method using SGR(Selective Ground Relay) and OVGR(Overvoltage Ground Relay) is generally used in ungrounded system. But this method only detects fault line and it has the possibility of malfunction. This paper proposed to advanced protection coordination method in ungrounded system. The method just using zero-sequence current can detect fault line, fault phase, fault section at terminal device. The general protection method is used to back up protection. In the case study, the proposed method has been testified in demo system by Matlab/Simulink simulations.


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