This paper describes and demonstrates the principle and efficacy of a novel direct current fault interruption scheme using a reactor\r\nin series with a controlled rectifier and a conventional AC circuit breaker. The presence of the series reactor limits the capacitive\r\ndischarge current from the DC filter capacitor at the output terminals of the phase-controlled rectifier. In addition, the series\r\nreactor along with the filter capacitor forms an underdamped series RLC circuit which forces the fault current to oscillate about\r\nzero. This synthetic alternating current can then be interrupted using a conventional AC circuit breaker. The selection criteria for\r\nthe series reactor and overcurrent protection are presented as well. Using the proposed scheme for an example case, a DC fault\r\ncurrent magnitude is reduced from 56 kA to 14 kA, while the interruption time is reduced from 44 ms to 25 ms.
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