Research And Application On Relay State Maintenance Reliability Of Evaluation Method

With the increasing numbers of protective relays maintenance, its maintenance work becomes more complex and the cost is also increased rapidly, which is difficult to meet the need of daily maintenance using the traditional maintenance method. In the actual operation, less or over maintenance of protective relays happens usually, which leads to unnecessary power outages affecting the normal production of the enterprises and residents electricity consumption. In recent years, the application of microcomputer based protection device can significantly improve the level of protection reliability and become the best choice of the automation or half automation maintenance. In order to constantly improve the automation level and work efficiency of condition-based maintenance of protective relay, based on the feasibility of condition-based maintenance of protective relay, this subject takes the status of maintenance into consideration and then gives the plan of maintenance work reasonably that can save costs and reduce the risk in the process of operation.Firstly, this paper summarizes the existing problems in the traditional statistical evaluation methods and analyzes the reliability of the protection should not just consider the protection of the device itself, but also take the secondary circuits and other devices into account, on this basis, a new reliability assessment method is proposed. The proposed method can accurately statistical the health index and failure index of operation status of equipment and calculate the probability of successful action using GO model, thereby improving the reliability of condition-based maintenance of protective relays to satisfy the current demand of automation assessment and provide a solid foundation for decision-making of condition-based maintenance.Secondly, the proposed assessment method of condition-based maintenance takes the dynamic monitoring and risk assessment methods into the process of maintenance, to overcome the deficiency of other maintenance methods which only concern the devices and ignore state of power grid, the proposed reliability model can provide scientific basis for policymakers and quantitative results. In addition, combining the risk of power system decision-making method of condition-based maintenance of protective relays is also presented in this paper, which uses the result of reliability assessment to decide the final maintenance program. And order of maintenance can be sorted according to the actual operation of the system, thus the efficiency of condition-based maintenance can be improved correspondingly.Finally, an example is used to verify the correctness and effectiveness of the proposed reliability assessment model and method by maintenance evaluation of all the transmission and transformation equipment in the grid, combined with the actual operation status and results of protection assessment to make decisions. The results show that the proposed reliability evaluation model and method can accurately simulate the actual operating state and the output can be used to provide reasonable protection plans for the policy-makers, which also can significantly improve the work efficiency.