A precise fault location scheme for HVDC transmission lines based on distributed measurement points with nonsynchronous traveling wave data

Precise fault location remains a critical problem in long-distance HVDC transmission lines. The deployment of distributed traveling wave measurement devices can effectively address this challenge. However, the distributed method depends on the wavefront arrival time at MPs. The presence of synchronization error at some MPs may lead to inaccurate fault localization. To resolve this challenge, this study proposes a method that employs the time shift characteristics of traveling waves, accounting for the time, line length, and wave attenuation characteristics at each measuring point to precisely identify the fault location. The method first identifies between which two measuring points the fault occurs through polarity analysis of the current wave. The wavefront arrival times at the far-end measuring points are subsequently mapped to the measuring points on both sides of the fault segment. Based on the fault segment, the wavefront arrival times at the two measuring points on each side are paired to form an initial fault ordered pair matrix. After recalculation, a fault location ordered pair matrix is generated, with each ordered pair in the matrix corresponding to a scatter point on the Cartesian coordinate system. Each scatter point corresponds to a fault location determined by a distinct wavefront arrival time. The virtual dataset is then used to remove anomalous scatter points with significant statistical deviations through an outlier rejection protocol. For the remaining scatter points, the deviation in wavefront arrival times is assessed based on the time difference between measuring points and the line distance. The final fault location scatter points are determined by considering the time deviation and the energy attenuation of the traveling wave. This method eliminates the need for additional equipment and can achieve accurate fault location results even under severe deviation conditions, thereby enhancing the reliability of distributed fault location. Finally, the reliability and practicality of the proposed method are verified through PSCAD/EMTDC simulation.