Condition-Based Maintenance Of Protective Relay Under The Support Of Self-Text Information

With the propagation of condition-based maintenance(CBM)of protective relay,the limitation of it has exposed.This thesis aims at furthering the superiority of CBM and enhancing the level of fine management by proposing specific measures to improve state assessment which based on the actual development of state assessment and under the support of device self-text information.Three topics were discussed in this thesis.The first is improving the current serve life assessment model.The second is presenting new health state indexes.The third is proposing state assessment facing devices in smart substation.The first chapter introduced the development of CBM and pointed out that device self-text contributes to perfecting it.The second chapter explained the method of evaluating reasonable serve life to solve the overlook of economy in current serve life assessment model based on the field data recorded by device self-text.At first,device defects were classed in to early defect,accidental defect and ageing defect.The opinion was showed that early defect should be considered.Field data was used as random censored data to increase the sample size.The occurrence times expectation was solved assuming the failure rate remain unchanged after maintenance.Then,the factors,like effect of CBM,configuration and possibility of mal-operation or refused operation,were considered in unit time cost function.At last,the feasibility was proved utilizing the field data of 220kV transmission line protection devices.The result showed enhancing the capability of finding out defects in advance is benefit.The third chapter discussed the new indexes facing to device compositions as supplement for state assessment.At first,the detail typical structure of devices was proposed.Then,the inside compositions were separated into power plug-in,logic components,optical fiber channel and man-machine interface.In each part,the limitation of current information was explained,some correlational researches of self-text were listed and new indexes were proposed.New indexes were mainly composed of analog self-test information and statistics self-test information and the cutoff values of assessment model were suggested according to standard and experience.The forth chapter designed state assessment taking a device as the smallest unit considering with the work above.At first,the typical structure,technology standards and mature self-text capability of relay protection device,merging unit,intelligent terminal and process level switch were summarized.Then,The design principles of state assessment for smart substation was proposed referencing the old one.At last,state assessment was separately proposed for the four types of devices.And the state variables,data acquisition methods and assessment models were listed.