Research On Practical Appliance For Condition-based Maintenance Of Protective Relays

For a long time, we have followed the periodic maintenance principle in the Power System, "perfect maintenance in time". With the development of Power System, the state grid structure is becoming more and more complicated and distributed over a larger area. Meanwhile, the amount of work and cost are increasing. In addition, Relay Protective are playing an important role in Power System with the growing amount of secondary equipments, which causes the negative effect of the periodic maintenance emerging. For instance, the increasing working load of maintenance manager, the shortening device lifespan led by frequent maintenance, the reducing economic benefits caused by the cut-off power line, ect. Furthermore, with the widely-applied of Microcomputer Protective Relays, the self-check level of devices is brought to a new high. Therefore, the common practice of regular detective system is undesirable. It must adopt condition-based maintenance according to the practical working condition of protective devices. This paper is mainly about:Firstly, this paper introduces the recent maintenance condition of Protective Relay devices, brings forward the present existent problems and analyzes the regular working factors of secondary equipments.Secondly, it discusses deeply about the appliance of on-line monitor and fault diagnosis technology in condition-based maintenance of Protective Relays. It begins with the research of reliability technology in electrical equipments at first. The on-line monitor should be added into the devices when the accidences happen frequently. Then concludes the existent using problems and realizes the on-line monitor in electrical secondary equipments. After that, it discusses the crucial step in condition-based maintenance, the fault diagnosis expert system, and presents a process of well-functional device diagnosis preliminary.Thirdly, it emphasizes the use of PSMS in transformation maintenance and provides the usage of the basic real-time and accurate data in Power Production and Security Management System to build condition evaluation system. It analyzes the protective devices according to Markov Model and establishes protective device and protected condition model. Then it works out the curve with the state space method, which shows the devices' unavailability changed with average maintenance period. In that case, it could gain the unavailability minimum and the relative average maintenance period which helps to confirm the best maintenance period.Based on the theory above, it gives some advices and suggestions aimed at solving the management problems about spare parts as expected. It also develops an intelligent spare parts management system, which can reflect their situation about warehouse and delivery, the quantity of type and demand. Finally, in order to provide an all-round guide to condition-based maintenance, the writer gives some way to ensure the reliable operation of secondary equipments after the arrangement and some details about inspection period and checking item, combined with some practical working experiences. It has very significant meanings and practical engineering value, which can ensure correct-acting rate of protection devices, enhance the transformation and operation management level of secondary devices and ensure the operation security of the systems.