Electric Field Analysis Of Composite Casing For 500kV Circuit Breaker

The circuit breaker is the key equipment in the operation of the power system,which is related to the stable operation of the power system.The high voltage bushing is an important part of the circuit breaker insulation.The electrical insulation of the high voltage bushing plays a vital role in the operation and maintenance of the circuit breaker.In view of the cold area in the northern part of the SF6 circuit breaker,the explosion of the bushing of the SF6 circuit breaker occurred.In order to meet the requirements of 500 k V system transmission reliability,preventing the accident of the explosion of the circuit breaker connection bushing occurred again.This paper uses COMSOL Multiphysics finite element analysis software to perform the study.The electric field strength of the composite bushing was analyzed,and the findings of study provide theoretical support for finite element modeling and the distribution rules and operation and maintenance opinions of the composite bushing.Firstly,the method and process of solving the electric field problem by finite element are summarized and summarized,and the possible mesh generation,infinite boundary selection,material selection,transient wave voltage fitting and other problems in the finite element modeling process are carried out.It is concluded that the infinite distance of the cylinder infinity with a diameter of 10 times the diameter of the bushing can reduce the calculation amount while ensuring the calculation accuracy.A double exponential fitting of the standard lightning strike waveform and the standard operating overvoltage waveform is obtained.Theoretical support for the calculation of bushing electric field distribution by finite element is provided.Secondly,based on the analysis of the casing structure of the circuit breaker,the finite element analysis software is used to establish the electric field analysis model under various environmental conditions: the model under ideal environment,the model under snow cover condition,and the model under pollution condition.The electric field distribution of the power frequency,the operating overvoltage and the lightning overvoltage condition are studied.The analysis results and conclusions of the influence of the external environment on the internal electric field strength are obtained.Finally,the paper also uses the three-dimensional finite element model and supercomputer service node to analyze the internal electric field strength of the bushing with SF6 liquefaction.The two three-dimensional mesh generation methods are compared,and the maximum possible electric field strength value is obtained according to the possible electrical parameters.It is pointed out that the SF6 droplets may be the cause of the accident,and the improvement measures are given.Through the analysis of the calculation results,some practical conclusions are obtained,which can provide useful reference for engineering design.