Reliability study on condition-based maintenance of protective relays

SUN Si-pei， XV Xi-dong
（College of Electrical Engineering， Zhejiang University， Hangzhou 310027， China）

Abstract： In order to study the reliability of protection system under condition-based maintenance，the condition assessment of protection system was introduced， and a Markov probability model was established. The state space method was used to calculated the states probabilities and reliability. Compared with routine maintenance， the influence of condition-based maintenance on unavailability of relay and the optimum routine test interval was analyzed.The influence of assessment rate and assessment interval on unavailability of relay was analyzed. The research results show that condition-based maintenance can extend maintenance cycle and increase availability of protection system.
Key words： protective relay；condition-based maintenance；Markov model；reliability