Improvement Research On Fem And Design On Medium And High Voltage C-GIS

C-GIS (gas-insulated metal-enclosed switchgear cabinet equipment) is a kind ofwhole set electric apparatus derived from the combination of GIS (Gas InsulatedSwitchgear) and conventional switchgear technology. It has been widely used because ofthe advantages of miniaturization, high reliability, free from environmental impact, lessmaintenance and convenient installation. In the tendency of high voltage, large capacityand miniaturization, resolving the contradiction between structure miniaturization designand high technology parameters as well as high dielectric strength has become thebottleneck in the design of C-GIS. To solve this bottleneck, insulation analysis should becarried out scientifically. However, static electric field numerical calculation is one of theeffective methods of the analysis of the electrical equipment insulation. As the most widelyused numerical analysis method, if FEM is applied on calculation of electrostatic field ofelectrical equipment, it will face problems of high solving precision of floating potentialconductor and unbounded field domain. In addition, it will also put forward higherrequirements on preprocessor meshing and solver for the existence of geometricalcharacteristics on thin electrodes as well as irregular boundaries and high precision as wellas efficiency of electric field calculation.To solve the above problems, the improvement of electrostatic field FEM analysistechniques and its application on the insulation analysis of C-GIS have been researched.And the density self-adaptive field domain subdivision algorithm is proposed, which canrealize reasonable transition of mesh grid. In condition of guarantee the quality of the mesh,this algorithm can avoid unnecessary increasing of grid number, which solves thecontradiction between accuracy and efficiency of computation. The accuracy andefficiency of calculating electric field are also improved by deducing and using localcoordinate FEM. Moreover, the problems in dealing with floating potential conductor andunbounded domain are realized by using virtual homogeneous boundary conditions andregional mapping method. Experiment of floating potential conductors between parallel plates is simulated and analyzed. Through comparing the simulation and experimentalreslts, it is verified that using the improved methods proposed in this thesis can calculateelectrostatic field problems more accurately and efficiently.Based on the above improved methods, a2D electrostatic field FEM numericalcalculation software by MATLAB platform is proposed, which integrates modeling,subdivision, solving and post-processing functions. And it covers practical modules ofimproved methods proposed in this thesis and provides electrostatic field analysis platformfor analyzing the electrical equipment insulation.In addition, according to the SF6insulation theory, national standards of switchgearand the size of vacuum circuit breaker interrupter, the structures of40.5kV and72.5kVC-GIS breaker chamber are designed. By using the self-developed software to simulateelectrostatic field, the insulation level of breaker chamber are checked, and referenceschemes are provided for the main technical parameters of the C-GIS design.