126kV 3断口真空断路器的重燃特性

为分析126kV 3断口真空断路器(VCB)的重燃特性,建立了包含重燃判据的126kV 3断口真空断路器的暂态等值模型。仿真得到了承担瞬态恢复电压(TRV)较高的1个断口发生重燃时的电流波形,为实现重燃电流尽早过零熄灭,在均压电容支路串联一阻尼电阻,结果表明:阻尼电阻取为振荡与非振荡衰减临界值时效果最佳;仿真分析了有无均压电容时,非重燃和重燃断口分别出现的过高TRV和工频恢复电压(PFRV),为保证断路器可靠开断及保护重燃断口外绝缘,在各断口并联金属氧化物避雷器(MOA)来限制过电压,结果表明:在1000pF均压电容上并联参考电压约为50kV的MOA时限压效果较好,且能满足热稳定要求。研究成果可为126kV 3断口真空断路器合理选取动态均压措施提供一定的依据。

Re-ignition Characteristics of 126kV Vacuum Circuit Breaker with Triple Breaks

To analyze the re-ignition characteristics of a 126 kV vacuum circuit breaker(VCB) with triple breaks,we established a transient equivalent model of a 126 kV VCB with triple breaks,which contained a dielectric re-ignition criteria.Thereby,we simulated the re-ignition current waveform of the break which took higher part of transient recovery voltage(TRV).A damped resistor was added in the grading capacitor branch to extinguish re-ignition current as early as possible.The results show that,the effect of damped resistor is the best when its value is threshold between oscillatory and non-oscillatory decay.Moreover,we simulated and analyzed excessive TRV which appeared across unre-ignition breaks and power frequency recovery voltage(PFRV) which appeared across re-ignition break in the presence and absence of grading capacitors.A metal oxide arrester(MOA) was shunted across each break to ensure breaking successfully and to protect the external insulation of re-ignition break by limiting excessive TRV and PFRV,respectively.Results show that,the voltage limiting effect is preferable when a MOA with reference voltage of 50 kV is in parallel with a grading capacitor of 1 000 pF,also the thermal limit can be satisfied,providing a basis for choosing proper dynamic voltage-sharing measures for a 126 kV VCB with triple breaks.