Research On Condition-based Maintenance Strategy Of Protective Equipment

With continuous development of maintenance level of secondary equipment of power system,the problems of "under-maintenance" and "over-maintenance" in the periodic maintenance of secondary equipment are gradually exposed.With advancement of online monitoring technology and improvement of enterprise management level,the maintenance of secondary equipment has gradually transitioned from regular maintenance and maintenance after failure to condition-based maintenance.This article provides certain guidance and assistance for field personnel to reasonably arrange maintenance schedule by conducting research on relay protection status maintenance strategies.Our paper main research contents are as follows:Firstly,this paper analyzes sources and characteristics of basic data commonly used in relay protection status maintenance;Reliability index and distribution of faults in the life cycle of protection equipment are analyzed;Quantitative expressions of reliability indexes such as failure rate and reliability under the Weibull distribution model are given.The above laid foundation for condition-based evaluation and decision-making of maintenance time.Secondly,aiming at shortcomings of in traditional periodic maintenance,a decision-making method of maintenance time based on health condition of protective devices is proposed.On the one hand,based on actual operating condition of protective devices and related evaluation standard,the health index is used to quantify pros and cons of various conditions in devices.The failure rate of devices under current operating condition is calculated.On the other hand,according to historical operational data of devices,the failure rate curve is segmented and fitted based on Weibull distribution.After the failure rate is substituted into the failure rate curve,actual working time of the protective device is obtained.Subsequently,the maximum maintenance period and optimal maintenance time of protective devices can be determined according to actual working time.The proposed method provides a reasonable basis for decision-making of maintenance time.Finally,the case study in terms of a regional power grid is carried out,which proves the effectiveness of the proposed method.Thirdly,this paper proposes a maintenance decision-making method of relay protection based on risks and maintenance benefits,and implements differentiated maintenance of protective equipment in terms of maintenance sequence and maintenance level.Risk assessment model which integrated primary and secondary systems is utilized.Actual failure rate based on condition-based evaluation of relay protection is taken as probability of risk occurrence,and impact of protective equipment failure on operation condition of primary system is ta ken as risk consequence.Maintenance sequence is determined by calculated risk value.Then this paper analyzes maintenance cost and impact on failure rate of relay protection under different maintenance levels.The maintenance risk benefit model is used to determine maintenance levels of protective equipment,which makes maintenance decision not only ensure reliability of relay protection,but also economics of maintenance is considered.The simulation calculation is carried out by using the IEEE9 bus system.The results show that decision-making method in this paper is reasonable.Finally,the research in this paper is comprehensively summarized.The future development direction and technical difficulties of condition-based maintenance technology of relay protection are forecasted.