双断口真空断路器开断特性的试验与仿真研究

Experimental and Simulation Research on Breaking Property of Double-break Vacuum Circuit Breakers

为分析双断口真空断路器的开断特性,建立了双断口真空断路器的合成开断试验平台和基于一种改进真空电弧模型的电磁暂态仿真平台。对开断电流、电弧电压、燃弧时间和瞬态恢复电压(transient recovery voltage,TRV)分配比例等参数进行了试验测量,通过仿真诊断等离子体参数,对试验结果进行了机理分析。结果表明:过长的燃弧时间会导致过大的燃弧能量和转移电荷,可能使电弧发生集聚;高压断口的延迟分闸会造成弧后残余等离子体特性的差异,从而加剧双断口真空断路器TRV分配的不均匀性;这2种情况均不利于开断。此外,双断口真空断路器均压电容的取值除了考虑TRV均匀分布外,还应兼顾弧后阴极表面电场分布的一致性,过大的均压电容反而不利于开断。因此,燃弧时间及其同步控制和合理均压电容值的选取是双断口真空断路器成功开断的关键。

In order to analyze the breaking property of double-break vacuum circuit breakers, we established a synthesis breaking test platform, as well as an electromagnetic transient simulation platform based on an improved vacuum arc model. By experiments, we measured breaking current, arc voltage, arcing time and transient recovery voltage （TRV） dis- tribution ratio. The mechanism of these results was then analyzed through simulative diagnosis of certain plasma parameters. The results show that overlong arcing time may lead to excessive arcing energy and excessive transferred electric charge, and consequently a constriction of vacuum arc. Delayed opening of the contact pair in break at the high-voltage side engenders the different characteristics of post arc plasma and consequently aggravates the non-equality of TRV distribution. Both of these conditions are detrimental to successful breaking. In addition, besides considering the uniform distribution of the TRV, the uniformity of the electrical field at the post-arc cathode should be also taken into ac- count in the selection of grading capacitors, since overlarge grading capacitance may be detrimental to successful breaking. It is concluded that the control of arcing time and its synchronism, as well as reasonable grading capacitance, are key factors for the successful interruption of double-break vacuum circuit breakers.