Single-End Transient Current Based Protection Method for VSC-HVDC Cable

Based on the boundary characteristic and frequency characteristic of cable, a protection method for VSC-HVDC cable is proposed in this paper, which only uses the single-end transient current signal. First, the frequency components of the currents at the DC-side and AC-side of the DC boundary are extracted by means of S transform, and the magnitude of the high frequency components of DC-side current is employed to detect the fault. Then, the ratio of the magnitude of the high frequency components of the DC- and AC-side currents is calculated to identify the internal fault from the close-up external fault. Finally, the ratio of the high and low frequency components of the DC-side current is calculated to identify the internal fault from the opposite external fault. This protection method is verified on basis of a two-terminal VSC-HVDC model with EMTDC/PSCAD. Various types of faults are simulated, and the simulation results show that this method can identify the internal faults under different conditions rapidly, while can ignore the external faults reliably.