860 / 2019-04-30 18:04:11

Analysis on the Misoperation of REL561 Protection and Its Logics Improvement

REL561; differential protection; fiber channel; misoperation

There was a case where REL561 fiber optical line differential protection misoperated during the process of fiber channel
switching in Qinghe 500 kV LineⅡ, causing the circuit breaker to trip out in three-phase as a result. The analysis in this paper shows that the problem is due to the logical defect of REL561. An improvement is proposed for the logic of the REL561 differential protection, and certain suggestions for the maintenance of REL561 protection apparatus are given.