A novel traveling-wave-based directional protection scheme for MTDC grid with inductive DC terminal

This paper presents a new rapid and reliable directional protection scheme for Multi-Terminal DC (MTDC) grid with an inductive DC terminal. The proposed method determines an internal or external fault easily by comparing the transient energy polarities of traveling waves measured at both ends of each line section. Compared with the conventional direction principle based on traveling waves, the proposed method performs more reliably in the case of an inductive terminal. Moreover, the double-end fault location method based on traveling waves is integrated into the protection scheme to predict the accurate fault location. The effectiveness of the proposed method is verified by a meshed DC grid modeled in PSCAD/EMTDC software. Extensive simulation results show the proposed method is able to determine internal or external faults correctly under conditions of different fault types, fault distances and fault resistances. Furthermore, the proposed method is also insensitive to the sampling frequency and noises.