Numerical Analysis Of Air Flow And Temperature Field Of 800kV SF₆/CF₄ Mixed Gas Isolating Switch

As one of the most used high-voltage electrical equipment in the high-voltage power grid,the high-voltage isolating switch,its operational reliability,service life and breaking performance will directly affect the stable operation of the power grid.When analyzing and researching the breaking performance of the isolating switch,it is necessary to comprehensively consider the common influence of the airflow field and the temperature field.In addition,the numerical simulation analysis of the airflow field and the temperature field also has a significant impact on the research on the breaking performance of the SF₆/CF₄mixed gas isolating switch.In this thesis,by studying the distribution of airflow-related characteristics in the air chamber of the isolating switch and the steady-state temperature field simulation analysis of the contact structure,it is of great significance to improve the breaking performance and operating performance of the isolating switch.800k V SF₆/CF₄ mixed gas isolating switch is regarded as the research object of this article,establishes a two-dimensional isolating switch model,uses finite volume method and combined with dynamic grid technology to perform numerical simulation analysis on the flow field in the isolating switch gas chamber,and obtain the distribution of pressure,velocity and turbulent flow energy of the gas in the isolating switch under the condition of different distances and keeping the inflation pressure at 0.8Mpa,by changing the moving speed of the movable contact to explore the influence of different contact speeds on the breaking performance of the isolating switch.In terms of temperature field simulation,using the method of magnetic-thermal coupling,the temperature field simulation analysis of the contact structure is carried out separately,and the influence of the contact area,load current and the closing state of the contact on the temperature rise of the isolating switch is studied.The isolating switch is optimized by changing the shape,thickness,length and radius of the conductive rod of the contact structure,in order to reduce the temperature rise of the isolating switch.Through the simulation results,it can be concluded that when the moving contact is kept at the same speed,as the distance increases,the gas pressure,velocity and turbulent energy distribution between the moving and static contacts are more uniform.When the moving contact is changed at the moving speed,the higher the moving speed of the contact,the more uniform the pressure,velocity and turbulent flow energy distribution of the air flow field,which is beneficial to improve the breaking performance of the isolating switch.In the analysis of the temperature field,within a certain range,the temperature of the isolating switch will decrease with the increase of the contact area.The greater the load current,the greater the temperature rise of the isolating switch,and the temperature rise when the closing state is good The change is small.By optimizing the shape and thickness of the contact,the maximum temperature of the isolating switch has been reduced by 4.6°C and 2.4°C respectively.Appropriately reducing the length of the contact structure and increasing the radius of the conductive rod can also reduce the temperature rise of the isolating switch.During the opening process of the isolating switch,appropriately increasing the moving speed of the moving contact will help improve its breaking capacity.Reasonable control of the contact area,load current and closing contact state is conducive to the stable operation of the isolating switch.By changing the shape,thickness,length and radius of the conductive rod of the contact structure,the temperature rise of the isolating switch is reduced and the optimization effect is achieved.Through the numerical simulation analysis and research on the airflow field and temperature field of the isolating switch,it is of great significance to improve its breaking performance,and provides a theoretical basis and reference for the reliability of the design and operation of the isolating switch.