Research On Coupling Of GIS Bus Bar Temperature Rise Multiphysics Based On Mixed Gas

As an important transmission equipment in the power system,the gas-insulated switchgear（GIS）bus bar has the advantages of compact structure and strong flow capacity,but it also faces the problem of large current and serious heat loss.In order to reduce the risk of overheating and ensure its safe and reliable operation,it needs to be analyzed by the electromagnetic heat flow coupling method,and then the heating is reduced by optimization means or optimized structure.In addition,due to the strong greenhouse effect of SF₆ gas,the replacement of pure SF₆ gas in GIS with SF₆/N₂ mixed-insulation gas is a future development trend.The existing research on SF₆/N₂ mixed insulating gas is mainly in the electric strength and insulation.The temperature rise characteristics of the mixed insulating gas in the GIS bus bar are not involved.The temperature rise is an important factor to affecting the replacement of SF₆ gas by environmentally friendly insulating gas.Therefore,it is of great significance to study the internal temperature distribution law of GIS bus bar of mixed environmental protection gas by multi-physics coupling analysis,and study GIS temperature online monitoring system.In this paper,ANSYS is used to establish an electromagnetic-fluid-thermal multiphysics coupling simulation model for a GIS bus bar which is filled with 30%SF₆-70%N₂ mixed insulating gas.using fluid multi-component transmission Finite element analysis method,To study the distribution law of electromagnetic field and temperature field on GIS bus bar.the Simulation results shows:The temperature at the top of the GIS inner conductor and the shell is higher than the bottom.The temperature is symmetric distrubution,and the upper temperature is higher than the lower temperature;the temperature rise of the shell and the conductor increases with the increase of the load current,and has a linear relationship with the ambient temperature;as the gas pressure increases,the temperature rise of the shell and the conductor gradually decreases;As the composition of the SF₆ gas increases,the rate in the temperature rise of the conductor gradually becomes slower.The GIS temperature online monitoring system based on infrared sensing is designed,which can monitor the GIS bus bar temperature and realize fault warning in real time,so as to ensure the safe and stable operation of the equipment.The simulation results were verified by testing a GIS system with voltage level of 126KV.The research results can solve the problem of high voltage GIS online temperature measurement,helpful for the early detection and elimination of GIS equipment failure,and it can also provide a basis theoretical for the promotion and application of mixed insulating gas in GIS.