Incorporating inductor‐capacitor branch for thyristor‐based DC fault current interruption

Abstract

Summary This paper investigates the interruption capability with the aid of a parallel capacitor branch and exploits the single current direction through a series thyristor with the DC system. Two DC current interruptions are introduced by providing superimposed oscillatory currents. The first one is that the capacitor branch (capacitor and inductor) is continuously connected in parallel with the system where the capacitor is charged from the system during the normal operation. Due to fault occurrence, the capacitor branch including an inductor produces an oscillatory current that can make zero crossing through the series thyristor. However, the interrupting current is unfortunately after the second oscillatory peak current that the fault resistance can damp the oscillatory current. By changing the charged capacitor polarity, the second breaking concept is introduced depending on a precharged capacitor by the system voltage and then injecting the oscillatory current using a self‐triggered additional thyristor. The current interruption initiation is attained using the DC current raising. The interruption performance is evaluated using a thyristor‐based converter DC system.

Analysis and Experimental Research on a Novel Multi-Contact MVDC Natural Current Commutation Breaking Topology

“…In particular, the current commutates from the MS to the commutation branch due to a different DC breaking topology [12]. With the omission of the snubber circuit, decrease in the current change rate, and increase in transient recovery voltage rate before zerocurrent, a cascaded commutation circuit and a parallel LC branch series with a thyristor were used to improve the fault current interruption capacity in [13] and [14]. Moreover, the circuit breaker (CB) characterized by the commutation of a short-circuit current from the load-carrying branch to the auxiliary branch based on rapid and precise current control by the multilevel pulse-width modulation (PWM) converter allows for the elimination of active semiconductor devices from the load current branch [15].…”