Status evaluation of protective relays based on the membership function in fuzzy normal distribution

Based on the practical operating experience,this paper describes the results of qualitative evaluation by quantitative information in status evaluation of protective relays.It uses fuzzy comprehensive evaluation in the quantitative evaluation of relays.Based on researching and selecting the characteristic parameters of devices,this paper makes the membership function in fuzzy normal distribution show status information,then studies its feasibility comparatively.Example shows that this membership function associates status information with performance characteristics well when evaluating protective relays.The method reflects the current operating condition properly,which is in line with the variation rule of the device operating status.The evaluation results can provide scientific basis for state maintenance and risk assessment.