电容缓冲式混合直流断路器的实验研究

Experimental Studies on Capacitance Buffering Hybrid DC Circuit Breakers

针对电容缓冲式混合直流断路器在无弧开断模式下,IGBT耐压过高造成通态损耗过大的问题,提出了一种新的开断模式——燃弧开断。利用PSCAD软件建立了仿真模型,经仿真分析可知,燃弧开断模式下的IGBT耐压要求相对无弧模式显著降低。设计了高速机械开关和换流实验回路,分析了实验等价性,进行了两种开断模式下的换流实验以及燃弧开断的等价性实验。实验结果表明,燃弧开断模式下的机械开关分断到一定开距时电流转移,能够承担逐渐上升的恢复电压,无需IGBT承担电压。无弧开断模式因存在机械开关固有分闸时间、初速度较慢和潜在"分流现象"等问题,IGBT需承担较高电压。实验结果在一定程度上验证了燃弧开断模式能够降低IGBT耐压要求的结论。

For capacitance buffering hybrid DC circuit breakers, this paper proposed a mode of breaking with arc to overcome the disadvantage of the mode of breaking without arc, which will lead to high conduction losses due to high voltage level design of IGBT units. A PSCAD simulation model was established. The simulation analysis showed that the maximum voltage of IGBT units decreased significantly when working in the mode of breaking with arc. The high-speed mechanical switch and the commutating test circuit were designed, and then equivalence of tests was analyzed. It conducted commutating tests of the capacitance buffering hybrid DC circuit breakers working in the two modes, as well as equivalent test in the mode of breaking with arc. The test results showed that the current transferred when mechanical switch already separated to a certain distance in the mode of breaking with arc, so mechanical switch was able to undertake all the rising recovery voltages and the IGBT voltage was almost zero. However, in the mode of breaking without arc, IGBT need to undertake high voltage because of the inherent opening time of mechanical switch, low initial speed, potential ＂diversion phenomenon＂ and so on. The test results have in some degree verified the simulation conclusion that IGBT voltage requirement can be decreased when working in the mode of breaking with arc.