High-voltage Electrical State Maintenance Strategy Study

HV power equipments are maintained regularly, in which the actual differences among them have not been taken into account, so that the measures bring a lot of problems such as surplus maintenance, waste of source or even side impact on the equipments' normal operation. Some power enterprises are discussing and applying some on-line monitoring technology and developing condition-based maintenance, but these measures are only in the experimental stage in some units and local parts without further applications. There are a lot of maintenance measures for power equipments, but which one is to be used should be based on condition-based maintenance technology. Because of the limitation of economy and technology, though the condition-based maintenance is ideal for use, it could not be applied very well. How to analyze and decide a condition-based maintenance measure is to choose optimal maintenance measure according to reliability-based analysis of equipments. This is called Reliability-based Condition Maintenance (RCM) measure adopted by many international industries.This paper presents detailed discussion on a comprehensive evaluation methodology based fuzzy theory, by comparing periodic maintenance and condition-based maintenance, combined with risk and reliability analysis. For the case of HV circuit breaker, by investigation of the fault characteristics and faulty condition, this paper indicates for condition-based maintenance which parameters must be monitored, namely main contact temperature, dynamic contact resistance, mechanical vibration, current wave during opening and closing, breaker's journey and monitoring of time characteristic during opening and closing etc. Taking into consideration of the HV circuit breaker's operation in the Century Power Company, and with some local experiments, analysis has been done for some problems to maintenance and monitoring in operation, and some measures are presented to solve the problems. Also in this thesis, regarding SF₆ circuit breaker, analysis on economy aspects are given for power system condition-based maintenance technology.The main research of the thesis involves the following parts:Firstly, maintenance strategy of power equipments is studied based on venture analysis, presenting the flow chart and principles for venture management.Secondly, fault mechanism of HV circuit breakers are fully accounted for case studies.Thirdly, for an example of HV SF6 circuit breaker, a fuzzy theory-based comprehensive evaluation strategy is presented, giving ameliorative methods for maintenance management.Finally, economy analysis on condition-based maintenance is carried out.The research results of this thesis present a deep insight into the condition-based maintenance theory and technology, and provide a base platform for practicable development of monitoring software to be applied in power plants.