Simulation Study Of Electric Field And Temperature Field Of New Insulating Gas Switchgear

27.5kV switchgear is an important part in the field of high-speed railway power supply.In recent years,gas insulated switchgear(C-GIS)has gradually replaced the traditional switchgear,and its development in the field of 27.5kV switchgear has also attracted attention.Insulation and temperature rise of C-GIS has always been a problem that needs to be sovled.Although CF3 I is regarded as one of the most likely alternatives to SF6,at present,the study of CF3 I only stays on its own discharge characteristics.This paper takes 27.5kV C-GIS as the object,using COMSOL software and based on multi physical field coupling.The main contents of the paper include:Firstly,the bus of 27.5kV C-GIS is taken as the object.The temperature field of the C-GIS bus is analyzed based on finite element method of coupled magnetic-fluid-temperature fields.Analyze the heat dissipation capacity of different proportions of CF3I/N2.Finally,it is determined that the component with the closest heat dissipation capacity to SF6 is 30% CF3 I /70% N2.Secondly,taking the new 27.5kV C-GIS as the object,the lightning stamping test is carried out on the bus room and circuit breaker room.It is concluded that the maximum field strength of the bus room and circuit breaker room is less than the critical breakdown electric field strength of 7.79 kV/mm.The insulation capacity of 30% CF3 I / 70% N2 is verified.Finally,finite element method of coupled magnetic-fluid-temperature fields,the heat dissipation performance of 30% CF3 I / 70% N2 insulation medium is studied.After applying the current of 1.1 times the rated current,the maximum temperature rise of the indoor space of the bus is 42.85 k and the maximum temperature rise of the conductor is 60.85k;The maximum temperature rise of the circuit breaker room is 16.85 k,and the maximum temperature rise of the conductor is 22.85 k,which meets the basic requirements of 70 K for the temperature rise of the switch cabinet and 50 K for the maximum temperature rise of the insulating components.The structure of bus bar in bus room is improved to reduce the maximum field strength and temperature rise.The final field strength is 3.10 kV/mm and the final temperature rise is 45.85 k and 37.85 K.