Research On Post-arc Dielectric Recovery Characteristics Of Double-break Vacuum Circuit Breake

Vacuum circuit breaker has become one of the important switchgear in the power system and contributed to the carbon peaking and carbon neutrality goals with the advantage of environmental protection of arc-extinguishing dielectric,its post arc dielectric recovery ability is the key to mark whether the circuit breaker can successfully break the fault current,especially the breaking ability of high current short-circuit fault.72.5k V single-break vacuum circuit breaker with rated current2500 A and rated short-circuit interruption current 31.5k A is determined as the object,the whole system of double-break vacuum circuit breaker is constructed and influencing factors and evolution mechanism of post arc dielectric recovery under power system fault interruption are studied.The combination of equivalent circuit simulation and finite element numerical analysis is used to analyse the sheath development process and internal electric field distribution of double-break vacuum circuit breaker under power system fault interruption.The main research work includes:Taking the short-circuit fault breaking of 110 k V transmission system as the object,the equivalent circuit model of 110 k V power system under the condition of short circuit failure is established based on Matlab/Simulink,the process of the circuit breaker breaking is analyzed,and the influence of the fault current limiter(FCL)and the power system parameters and fault distance on rate-of-rise of restriking voltage(RRRV)under terminal fault and short-line fault interruption is studied,and the cooperation mechanism of each element with circuit breaker in power system is explored.Based on the gas dynamic model of Boltzman equations,taking110 k V/2500A/31.5k A double-break vacuum circuit breaker as object,the development process of post arc sheath under short-line fault interruption is analyzed,the evolution of parameters such as electron density,ion density,potential electric field,electron temperature and ion velocity under different fault distances and the post arc development characteristics under different rated parameters and fault types are comparatively analyzed,and the improvement of breaking ability of vacuum circuit breaker by restricting RRRV is explained from the point of view of post arc dielectric recovery.The static electric field under typical fault interruption of 110 k V/2500A/31.5k A double-break vacuum circuit breaker is simulated by finite element method,and the influence of uniformity of voltage on insulation performance of double-break vacuum circuit breaker is analyzed.Based on the simulation calculation of the withstand voltage of the double break,the relevant capacitance parameters of each break are calculated,and the electric field distribution of key components such as the internal shield,the surface of dynamic and static contacts of the double break under different power system faults are analyzed,as well as the operating mechanism of residual particles on the surface of the shield on the electric field distribution.