Research On Electric Field And Temperature Field Of Main Circuit Module Of 12kV Solid Insulated Switchgear

As a member of medium voltage switchgear,12 kV Solid Insulated Switchgear(SIS)is an important part of power transmission and distribution system.The power quality of transmission system is affected by the operation reliability of SIS,and the operation reliability of SIS is constrained by its heat resistance and insulation performance.How to prevent the aging of SIS due to overheating,mechanical strength decline and gap breakdown due to low insulation margin has become the key point of SIS research.In this paper,the mathematical model of a 12 kV SIS is established.The temperature field and airflow field distribution of the switchgear under steady state condition are simulated and analyzed by finite element software.Then the electrostatic field distribution of the main circuit module of the switchgear is calculated and the local area is optimized to meet the insulation design requirements.Finally,the temperature distribution of the new 2500 A large current SIS is explored and optimized,which provides a theoretical basis for the thermal design of the SIS.The specific content includes the following parts:1.The model of 12 kV SIS was established.The temperature field of the 3D model of the switchgear with rated current of 1250 A were simulated and analyzed by using computational fluid dynamics(CFD)software and basic heat transfer theory,taking into account factors such as the skin effect of AC current,contact resistance of conductor,connection bus bar and so on.Temperature rise test of the prototype is carried out with the temperature rise test of medium voltage switchgear in the national standard.The temperature rise of each key point of the current-carrying circuit conductor is measured and recorded by thermocouple.On this basis,the data comparing with the simulation results shows that the errors are within the range of0.8%~9.2%.This shows the accuracy and practicability of the simulation calculationmethod of temperature field.It can provide reference for the thermal design of related solid insulated switch products.2.The model of main circuit module of 12 kV SIS is established,and the 3D electrostatic field is simulated and analyzed by using finite element software ANSYS Maxwell.By increasing the fillet of the insulating tie rod and the length of the shielding net,the region with high local field intensity in the main circuit module is optimized,and the distribution of field intensity around the module is improved.The validity of the optimization scheme is verified by partial discharge,power frequency and impact withstand voltage tests on the prototype.3.Using the above thermal analysis method,the distribution of temperature field and airflow field of the new 2500 A large current SIS is analyzed,and the optimization scheme of temperature rise for improving the internal structure and the performance of insulating material is put forward.The improvement of the internal structure increases the overall air passage,and helps to increase the exchange flow of air flow between the chambers in the cabinet.The improvement of insulating material performance enhances the heat conduction efficiency of conductor,effectively reduces the overall temperature of cabinet,and can provide reference for the optimization of heat dissipation of similar products.