Title :
Performance of ROCOF relays for embedded generation applications
Author :
Affonso, C.M. ; Freitas, W. ; Xu, W. ; da Silva, L.C.P.
Author_Institution :
Dept. of Energy Syst. & Control, State Univ. of Campinas
Abstract :
The performance characteristics of rate of change of frequency (ROCOF) relays for embedded generation islanding detection are investigated. The concepts of detection-time versus power-imbalance curve and critical power imbalance are proposed. These concepts are employed to determine the factors that may affect the islanding detection capability of ROCOF relays. The factors analysed are voltage-dependent loads, load power factor, generator inertia constant, feeder length and X/R ratio and multi-embedded generators. In addition, false operation due to faults on adjacent feeders is investigated. The results show that ROCOF relays may become ineffective for islanding detection if the power imbalance in the islanded system is smaller than 15%. In addition, these devices have a high risk of false operation
Keywords :
distributed power generation; fault diagnosis; power factor; power generation faults; power generation protection; relay protection; ROCOF relays; XIR ratio; detection-time; false operations; feeder faults; feeder length; generator inertia constant; islanding detection; load power factor; multiembedded generators; power-imbalance curve; rate of change of frequency relays; voltage-dependent loads;
Journal_Title :
Generation, Transmission and Distribution, IEE Proceedings-
DOI :
10.1049/ip-gtd:20041079
