| As the important controlling and protecting equipment of the power system,high voltage breaker plays the role of switching lines and interrupting short-circuit current,the reliability of high voltage breaker makes significant influence to the power grid's safe and stable operation.The complex fault types of high voltage breaker includes mechanism,insulation,control circuit and other failures.The reliability of high voltage breaker requires deep-going research.This thesis takes a 252kV SF6 breaker as research object to analyze the mechanical reliability.For the purpose of analyzing the reliability and lifetime of high voltage breaker,the system reliability model is built based on the reliability analysis model of single parts.This thesis's main content includes:(1)Introducing the project's research-background and principle of spring operating mechanism.Illustrating the domestic and foreign research situation of reliability engineering and high voltage breaker reliability.(2)The concept of stress-strength interference model is introduced and some methods of reliability analysis are presented and compared.(3)The reliability of opening lever arm,closing lever arm,mechanism linkage,opening lever,closing lever,insulation bar arm and insulation bar are analyzed.Based on the strength degradation model of materials,lifetimes of parts are analyzed by the relations of reliability and operating times.(4)The reliability and lifetime of opening and closing springs are analyzed.The distribution of maximum shear stress strength is acquired by the calculation method of cylindrical helical spring's maximum shear stress.By combining the strength degradation and stress relaxation model,the relation of reliability and operating times are analyzed.(5)The reliability block diagram model and Markov model of high voltage breaker's mechanical reliability are constructed and the curves of system reliability and lifetime are calculated.The influence of repair rate in Markov model is also analyzed. |
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