A Novel Method for Determining the Source of the Second Traveling Wave in Fault Location of VSC-HVDC Lines

The traveling wave-based fault location methods for VSC-HVDC lines typically require detecting the second traveling wave after faults occur. However, the second traveling wave may come from different reflected traveling waves, leading to different ways of calculating the fault distance. Therefore, it is necessary to determine the source of the second traveling wave, which is one of the difficulties. This paper analyzes the characteristics of the second voltage traveling wave from different sources and proposes a novel determination method. It uses the sign of the voltage change rate at the arrival time of the second traveling wave front to determine its source and is applicable to both sin-gle-line-to-ground faults and line-to-line faults. The effectiveness of the proposed method is verified in PSCAD/EMTDC. The simulation results demonstrate that this method can accurately determine the source of the second traveling wave under various fault conditions.