Investigation of suppression effect of short-circuit current and voltage drop in multi-terminal HVDC by DC reactor

An HVDC grid will be required to avoid DC voltage collapse and operate the healthy lines continuously, even if a DC fault occurs at the remote end. Rapid fault clearing is essential for DC Circuit Breaker (DCCB) even though the requirement varies depending on DC transmission system configurations, Voltage Source Converter (VSC) design, transmission capacity, and DC reactor connected in series with the line/cable, etc. In this paper, the requirements for DCCB are analytically evaluated using a four-terminal radial HVDC network model. In addition, the method to mitigate each DCCB requirement is also investigated. The results show that DC fault interruption current and fault clearing time are achievable by using a mechanical DCCB with the active resonance current zero creation scheme by applying DC reactor at a proper value.