Electric And Flow Field Numerical Simulation For High Voltage SF₆ Circuit Breaker

As the important specification of the high voltage SF6 circuit breaker(HV SF6 CB), the insulation and breaking performance are effected by the electric, magnetic, thermal, mechanics, materials and other physical parameters. The numerical computation of electric field and flow field with high precision and high efficiency, and the study on the dynamic distributions of electrical parameters and flow parameters, has practical significance to the operation performance for the HV SF6 CB.For HV SF6 CB, there exist multi-dielectrics media and complex structure in the arc quenching chamber. Based on the advancing front technique, by improving the generation pattern of node and element, applying the technology of domain decomposition, an improved advancing front mesh automatic generation algorithm is proposed. According to the principles of finite element method(FEM), a two-dimensional axisymmetric electric field mathematic model has been discretized and solved. And the electric field distribution in the arc quenching chamber for the 252kV SF6 CB is simulated, and the dynamic variation of the electric field strength with the breaking process is obtained and analyzed.For studying the unsteady, compressible gas flow field problem in the arc quenching chamber for the HV SF6 CB, the body-fitted grid is generated by adopting the numerical solution method of differential equations. Then the gas flow control N-S equation is discretized by finite volume method(FVM) with the combination of Jameson central scheme+artificial viscosity method, and a four-step Runge-Kutta time marching method is used for solving the discrete first-order partial differential equations of time. For resolving the flow field computational domain dynamic variations with the breaking process, the domain decomposition technique and mesh slipping method have been adopted. Finally, the gas flow field in the arc quenching chamber for the 252kV HV SF6 CB is numerically computed and analyzed, and the gas flow parameters, such as velocity, density, pressure and mach number have been obtained.For the computational complexity of the dielectric recovery property, based on the structure quadrilateral grid applied the gas flow field computation, converted it to the triangular element used in the analysis of electric field, and insure the electrical parameters and the flow parameters for the calculation of dielectric recovery property with the same node information, the interpolation error is avoided, and the calculation accuracy is improved.By developing the QuickWin graphics application, and using computer graphics visualization method, the relevant information of numerical computational progress including the pre-treatment, numerical solution process and post-processing is visualized. And the program of regional grid automatically generation, electric field computation, gas flow field computation and dielectric recovery property computation for the arc quenching chamber of HV SF6 CB has been obtained.