Research on applicability of current fault component polarity pilot directional protection for VSC-HVDC cable lines

It is pointed out that DC transmission line current mutation characteristic protection and AC line protection traveling wave current polarity protection are essentially the same. The pilot directional protection of VSC-HVDC cable lines can be achieved using current fault component polarity and fault component protection criterion. In respect to the presence of proximal relay protection disoperation, fault pole choose and other issues, when the principle is used for the protection of VSC-HVDC cable lines, the applicability study is conducted and solutions are given. The system of VSC-HVDC is built in PSCAD and frequency-depend parameter cable line model is adopted. The simulation results show that the principle proposed is simple, reliable, practical with absolute selectivity and only low sampling frequency is needed.