Research On Life And Reliability Assessment Methods Of High-voltage Circuit Breakers

Based on the critical defect data of Yunnan power grid 110 kV and above voltage class circuit breakers from January 2012 to December 2014 and the statistical analysis of the results of the CIGRE reliability survey,this paper analyzes the key factors of circuit breaker life,and understands the various factors that affect the failure of high voltage circuit breakers and their influence mechanisms.On the basis of the above analysis,the life evaluation study of circuit breakers is carried out,and the general technology of the whole life of circuit breakers and seal aging is studied.Because the electrical life is the main factor that affects the overall life of circuit breaker,the N-Ib curve method in the electric life diagnosis method is used to predict the electric life of circuit breaker,and thus the circuit breaker life is evaluated.On the basis of the overall life evaluation of circuit breakers,the general technology of seal aging is studied for SF₆ switching equipment,the aging mechanism,seal structure design and assembly process of sealed materials are described,and the aging research of the main seal materials used for switching equipment is carried out.The main factors affecting the aging process are analyzed and the aging rules are summarized.Simulating the actual operating conditions,considering the thermal stress and mechanical stress,the accelerated aging test of the seal ring product is carried out,the aging development law of the seal ring is studied,and the aging process of the seal ring is summarized.A reliability evaluation method for high voltage circuit breakers based on fault tree and improved fuzzy analytic hierarchy process is proposed.The fault tree of high voltage circuit breaker is established,and the fault of complex circuit breaker system is subdivided into various basic fault types.Then,through the improved fuzzy analytic hierarchy analysis method,the fuzzy judgment matrix between the fault factors of the high voltage circuit breaker is established,and the fuzzy uniform limit conditions for solving the weight of each fault factor are converted into the constrained optimization problem.Firefly algorithm is used to obtain the optimal result of weight.Based on the actual operation of high voltage circuit breaker,the reliability evaluation model of high voltage circuit breaker is established.Unbuckling electromagnet is one of the most important components in the circuit breaker spring movement mechanism.During the actual use,the aging of the unbuckling coil may occur.This may be caused by two reasons.On the one hand,it may be due to the aging of the coil due to the accumulation effect of the current due to the long normal use time.On the other hand,it may be short-time or continuous working under maximum load and overload.The aging phenomenon caused by the acceleration of the accumulation effect of the current.The aging of the coil is very harmful.In the most serious cases,the coil will be burned,causing the detaching electromagnet to lose its detaching function,causing the circuit breaker closing or detaching function to fail,affecting the operation of the power system.In this paper,the reliability of electromagnet is studied through simulation analysis and experimental research.According to the separation and closing of the electromagnet,the main reasons for its burning are analyzed experimentally,and the coil power tolerance time and its influence on the motion characteristics are studied.The key techniques for the reliability of the unbuckling electromagnet and the main reasons for the coil burning are obtained.