DC current interruption in HVDC SF6 gas MRTB by means ofself-excited oscillation superimposition

摘要

The Kii-Channel HVDC Link under construction in Japan is equippednwith metallic return transfer breakers (MRTBs) in one converter station.nA new MRTB for an interrupting current of 3500 A DC was developed. Toninterrupt a DC current, a method that produces a current zero point bynsuperimposing a self-excited oscillatory current on a DC arc current wasnemployed. For this purpose, a LC circuit was coupled in parallel to a SFn6 gas circuit breaker. Developing a SF6 gasncircuit breaker that has a large arc voltage drop gradient againstncurrents permitted a large oscillatory current to be generated. Anmodified Mayr-type dynamic arc equation was newly presented. The DCninterruption limits calculated using this equation agreed with thenmeasured values