Study On The Method Of Condition-based Maintenance Of Relay Protection

For a long time, the maintenance mode of relay protection equipments is based on the principle of mainly periodical inspection, supplemented by break maintenance. With the development of power system, the grid structure is becoming more and more complicated and distributed over a larger area so that the amount of maintenance workload and cost are increasing. In addition, with the widely-applied of microcomputer relay protection, the self-check level of devices is brought to a new height. If periodical inspection is continued to be the major method, it will result in excessive maintenance, reducing the operation stability and reliability of equipments and causing manpower, material and financial resources waste. Therefore, the regular periodic inspection system is undesirable. Condition-based maintenance according to the practical operation conditions of protective device should be adopted to meet the development of power system. The research on condition-based maintenance theory and method of primary equipment has obtained a certain result, but the research on condition-based maintenance method and engineering application of protective equipment just start and practical achievement is seldom. Based on this point, this thesis makes a study on the condition-based maintenance method of relay protection, the detail work is as follows:The connotation of condition-based maintenance of power system is expounded in the thesis. The importance of state monitoring of relay protection in condition-based maintenance is described and the current problems are pointed out.The key points of condition-based maintenance of relay protection are state diagnosis, state assessment and maintenance decision-making method.Aiming at the method of state diagnosis, this thesis divides the state diagnosis of protective devices into two categories: state diagnosis of static characteristic and state diagnosis of dynamic characteristics, and determines suitable diagnosis method respectively.The risk evaluation model is established according to the physical structure and action process of protective device using state-space approach. The thesis establishes the state assessment method based on apparatus patrol and operation management information by means of apparatus pre-test data, family quality bug and equipment history working quality information. A comprehensive assessment method for relay protection condition is proposed on the basis of three elements: state diagnosis, risk assessment, apparatus patrol and operation management information.On the basis of establishing the comprehensive assessment method for protection equipment condition, the determination of condition-based maintenance time according to the result of state assessment is another key issue. The thesis proposes the maintenance decision-making method of relay protection considerting different meteorological conditions in accordance with the necessity analysis of taking meteorological conditions into consideration in maintenance scheduling, and mainly studies the calculation methods of risk analysis of protection maintenance under the consideration of short-term maintenance plans, long-term maintenance plans and different meteorological factors, different meteorological stages respectively. Analysis of the examples shows its validity mentioned above.