Wave front rising time based traveling wave protection for multi-terminal VSC-HVDC grids

To deal with the problem of high-resistance fault identification in multi-terminal VSC-HVDC grids, a novel wave front rising time based traveling wave protection is proposed in this paper. For such purpose, the traveling wave is firstly analyzed from its generation, propagation to refraction for the sake of discovering its influence factors. The wave front rising time is revealed to be approximately proportional to the fault distance while insensitive to the fault resistance and operation condition during line propagation. Moreover, it significantly increases when refraction occurs at the line terminal. Secondly, based on these characteristics, the novel wave front rising time based traveling wave protection as well as its analytical setting calculation is proposed. The proposed protection can work with higher-fault-resistance identification capability and faster-operating speed, compared with other protections. Besides, the efficiency of the proposed protection setting calculation is greatly improved since tedious electromagnetic transient simulations are avoided. Finally, the feasibility and robustness of the proposed protection are validated by a four-terminal VSC-HVDC grid on PSCAD/EMTDC platform.