Insulation Design And Performance Analyses Of The High Voltage Bushing

The Insulation performance of the modern electrical equipment will directly influence the entire operation properties of the electrical power system. And the fine insulation performance is the key consideration for ensuring the normal operation of the electrical apparatus and the power system. As a typical high electric field insulation parts, the high voltage bushings are applied with high electrical equipments. With the increase of the voltage level of the power system, the higher insulation requirement is proposed for the high voltage bushing.The high voltage insulation bushing of the 800kV SF6 circuit breaker is taken as the research object. Based on the technical requirements of ultra high voltage circuit breaker, insulation structure has been analyzed and designed. The electric field distribution and anti-seismic performance of the bushing are analyzed with Finite Element Method (FEM). Moreover, the influential factors, such as internal and external insulation, the operation condition and the anti-seismic performance are taken into consideration, and the improvement approaches are presented.In order to improve the internal and external electric field distribution of the bushing, the grounding shield and the middle floating shield are introduced inside the bushing. In which, the internal electric field strength is mainly improved by the grounding shield, and the external field strength distribution is mainly improved by the middle floating shield. Based on the above analyses, in order to improve the insulation performance, an improved genetic algorithm is applied as the optimized method for reducing the discharge possibility on the flange, and the grading rings are introduced on the top of the bushing and the shielding rings are mounted on the end part. The research results show that the structure of the insulation umbrella is the main influential factor for the dry lightning voltage of the bushing. Based on the comparison of the electric field distributions for different umbrella structures, the insulation improvement approach is proposed. Additionally, the material properties of the porcelain bushing are changed in order to uniform the electric field effectively. That is, the high strength porcelain is adopted in the top and bottom terminals and the conventional porcelain is adopted in the middle part of the external porcelain structure of the bushing.To guarantee the overall performance of the bushing, based on the insulation analyses and optimal design of the high voltage bushing, the anti-seismic performance is analyzed. According to the program design, the numerical simulation is provided for the performance analyses of the high voltage extra high voltage and ultra high voltage insulation bushing.