Fault Location Method for Continuous Transmission Lines of High-Speed Railway Based on Low-Voltage Measurements at Box-Type Substations

Precise fault localization for high-speed railway continuous transmission lines is indispensable for sustaining power supply reliability and mitigating power outages. This study presents a novel fault localization approach that uses low-voltage information obtained from box-type substations distributed along continuous transmission lines. The proposed scheme relies on the distribution features of the positive-to-negative sequence voltage ratio (rPNV) measured at the low-voltage terminals of box-type substations. Results reveal that the magnitude of rPNV gradually declines from the main substation to the fault location in the fault upstream area, while it stays nearly unchanged in the downstream section. Based on this feature, the faulted section is initially determined by means of the nearest neighbor clustering method. Subsequently, the precise fault location is calculated by solving equations that combine the sequence voltage ratio at the fault point with the measurements obtained from the main substation and box-type substations downstream of the fault. The proposed method requires only asynchronous low-voltage measurements, eliminates the need for fault impedance modeling, and is applicable to various asymmetric faults. Simulation tests under different fault types, fault resistances (up to 2000 Ω), noise conditions, and neutral grounding modes demonstrate that the method achieves high accuracy and robustness.