A Novel Fault Detection and Fault Location Method for VSC-HVDC Links Based on Gap Frequency Spectrum Analysis

This paper proposes a one-end gap-based fault location method for VSC-HVDC transmission line using the fault current signal. Using the post-fault current time series, the frequency spectrum is generated for measuring the gaps between the contiguous peak frequencies. This method is able to locate the fault by analyzing the single-end fault current, which guarantees a faster response than using two-end data. The new gap-based approach is able to give accurate fault detection using any appropriate range of post-fault signal. Furthermore, the proposed method is fault resistance independent. A two-terminal VSC-HVDC system is modeled in PSCAD/EMTDC. The algorithm is verified by studying different cases of different fault resistances in various fault locations. The result shows that the proposed method gives an accurate and reliable fault location detection along DC transmission line. In addition, the proposed algorithm can be potentially used in other HVDC systems.