EVALUATION OF PROTECTION SYSTEM PERFORMANCE USING DFR AND RELAY COMTRADE FILES

The paper proposes an automated analysis system, based on data generated by Digital Fault Recorders, capable of evaluating the protection system operation behavior against expected patterns, pinpointing possible malfunctions and indicating problems prone to rise in the future. The protection performance is evaluated focusing on the external behavior of the relays and the communication channels. This approach allows for dealing with equipment from different technologies with few changes in the evaluation software. The relay performance can also be checked against simplified models of the protection elements. Instead of developing intricate and complete models of commercial relays, which are dependent on manufacturer information, simplified models, based on classic protection theory, allows for simple but robust reasoning tasks, like comparing relay operation against an over-current directional or a line current differential algorithm. The basic idea is to use the output of these virtual relay elements as a possible warning to the protection engineer. The system was put in service at LIGHT S.E.S.A., a major distribution utility in Brazil. The authors believe that this evaluation system can be a relevant step in protection and fault analysis in LIGHT S.E.S.A. and similar companies, as it aggregates quite useful information to the automated fault pre-analysis