Analisis And Design Of Insulation Of Multi-Breaks In Series UHV SF₆Circuit Breaker

With the increas of the transmission line voltage and the capacity of the power system,higher insulation is required for the high voltage electrical equipment. And fine insulationequipment directly affects the operation, the safety and the stability of the overall powersystem. With the rapid development in national economy, there is a growing need inelectricity. In order to optimize the energy distribution, achieve the power transmissionfrom west to east and north to south in a large-scale, and to realize North-South assistancein water and power, the power grid of million-volt-level AC and±800kV UHV DC systemshould be accelerated to construct as the core of the national grid. And a UHV ACdemonstration project came into being proposed. As an important controlled and protectedequipment, the characteristic of the insulation of the circuit breaker is significant. Effectiveapproaches of analysis and design of the insulation are field simulation andfield-uniformity design based on the numerical analysis of3D electric field.In response to thin uniforming shield electrode existed in the large field of the arcquenching chamber with a structural characteristic of multiple dielectric medium andasymmetric shunt capacitors of multi-breaks in series, and the solution of the contradictoryof the calculation accuracy and efficiency, a combination of finite element method （FEM）and domain decomposition method（DDM） is given out in this thesis, three-dimensional（3D） electric field of the252kV high voltage SF₆arc quenching chamber with single breakhas been calculated. And the contradictory of the calculation accuracy and efficiency hasbeen solved. Moreover, three insulation allocation schemes of the shunt capacitors havebeen given out. And the comparative analysis of the electric field distribution of differentschemes has been illustrated. Furthermore, the quantitative analyses of the electric fieldintensity, distribution of the contact contour and the field uniformity have been obtained.Based on the research of the252kV SF₆circuit breaker, the dynamic insulationcoordination property covers the dynamic insulation of each break and the design of themulti-breaks in series.3D electric field of the four-breaks in series SF₆circuit breakers isnumerically simulated using FEM and DDM. And the location of the maximum electricfield intensity and the field distribution along the surface of the movable and the fixed contact are calculated and figured out. By the comparative analyses with differentinsulation structures in series, the variations of the electric field intensity are obtained andillustrated. Moreover, by introducing the shielding covers and parallel capacitors, thedesign of each arc quenching chamber unit is accomplished and the insulation property ofthe1100kV fourfold-breaks in series UHV SF₆circuit breaker is analyzed.