High Fault-Resistance Tolerable Traveling Wave Protection for Multi-Terminal VSC-HVDC

To deal with the high-resistance fault identification problem in multi-terminal VSC-HVDC, this paper proposes a high fault-resistance tolerable traveling wave protection. First, the non-unified characteristic of traveling wave front between internal and external faults is revealed, which makes the high-resistance fault identification difficult. Then, the traveling wave propagation regarding the reflection and refraction process at the remote end is investigated for the difference, and the distinctive current reduction phenomenon during the interval of two incident traveling waves under internal fault with resistance is discovered. Moreover, the current reduction phenomenon would become more significant with the increase of fault resistance. Based on this phenomenon, the high fault-resistance tolerable traveling wave protection is proposed, which could identify the high-resistance fault accurately with single-end measurement and is insensitive to fault resistance. The feasibility and robustness of the proposed protection are validated in a four-terminal VSC-HVDC.