Single-Terminal Fault Location Method for LCC-HVDCs Using Time-Frequency Concentrated Wave-Process Analysis

Existing single-terminal traveling-wave-based fault location methods for LCC-HVDCs encounter difficulties in wave velocity selection, wavefront identification, and ensuring robustness. Reliably discerning the nature of the second reflected wave and precisely extracting its arrival time pose significant challenges, which are crucial for determining the two unknowns of fault distance and fault occurrence time in single-terminal methods. To circumvent these difficulties and explore an alternative single-terminal approach, this paper shifts the research focus to exploring fault distance information within the initial wavefront, combining the time-reassigned multi-synchrosqueezing transform (TMSST) with EXtreme Gradient Boosting (XGBoost) to analyze and correct a group of wave arrival times. An overdetermined fault location equation is formulated using independent frequency components, and the least squares solution for fault location is obtained, eliminating reliance on capturing the second reflected wave. Case studies demonstrate that the proposed method achieves an accuracy of hundred meters in most scenarios. While performance slightly deteriorates under high-resistance faults, dead-zone faults, and strong noise interference, the overall accuracy outperforms existing state-of-the-art methods.