基于SF_6替代气体的高压混合断路器开断特性

Interruption Characteristics of High-voltage Hybrid Circuit Breaker Based on the Alternative of SF_6 Gas

为研究基于SF_6替代气体的高压混合断路器的开断特性,搭建了气体间隙与真空间隙串联的混合断路器实验样机,向气体间隙分别充入SF_6气体与CO_2气体。基于合成回路,实验对比两种混合断路器的开断性能差异,分析气体灭弧介质对混合断路器开断性能的影响,讨论影响CO_2气体间隙开断能力的主要因素。实验结果表明:合理的开断控制策略下,真空间隙可为气体间隙提供约100μs的介质强度恢复时间,但受限于旋弧灭弧室中CO_2气体较慢的介质强度恢复速度,相较于SF_6气体间隙,CO_2气体间隙难以配合真空间隙获得理想的开断效果;CO_2气体间隙充气压力自0.6 MPa增大至0.8 MPa对其开断能力提升有限;电流过零后500μs,0.8 MPa的CO_2气体间隙耐压水平仅为8 k V。建议结合CO_2气体自身特性优化气体灭弧室结构,提升其开断能力,为发展基于CO_2气体的大容量混合断路器奠定基础。

To investigate the interruption characteristics of a high-voltage hybrid circuit breaker based on the substitute for SF6 gas, we prepared a test prototype of the hybrid circuit breaker composed of gas gap and vacuum gap, while the gas gap was filled with SF6 gas and CO2 gas, respectively. Based on the synthetic test circuit, the interruption performances of two types of hybrid circuit breakers were tested and compared. Moreover, the influences of different gas interruption dielectrics on the interruption performance of hybrid circuit breaker were analyzed. The influential factors on the interruption capacity of CO2 gas gap were discussed. As the test results convey, under favorable operating strategies, vacuum gap can provide about 100 μs for the dielectric strength recovery in gas gap. But limited by the slow dielectric strength recovery speed of CO2 gas in rotating arc gas interrupter, CO2 gas gap cannot cooperate with vacuum gap to achieve satisfied interruption performances compared to SF6 gas gap. The improvements in the interruption performance of CO2 gas gap are limited while increasing the gas pressure from 0.8 MPa to 0.6 MPa, as the breakdown voltage of 0.8 MPa CO2 gas gap is only 8 kV after 500 μs since current zero. It is suggested that the structure of gas interrupter should be optimized after combining with the properties of CO2 gas so as to enhance its interruption capacity and provide a basis for the development of hybrid circuit breaker based on CO2 gas.