A Traveling Wave Directional Protection Based on Variational Mode Decomposition for Traction Power Supply System

To solve the problems of power quality and phase-links of the high-speed and heavy-load electrified railways power supply system, this paper presents a traveling wave-based directional protection for continuous co-phase autotransformer traction power supply system (TPSS). Basically, phase-mode transformation is used to decouple the transient fault signals to get aerial mode components and then the forward and inverse traveling wave is obtained by calculating the aerial mode components. The variational mode decomposition (VMD) method has no mode confusion and can obtain the accurate instantaneous amplitude and frequency, so it is used to extract the intrinsic mode function (IMF) components, which are further calculated to get the modulus maxima. Two relays at the ends of the protected catenary are used to detect internal and external faults. Consequently, a continuous co-phase traction autotransformer TPSS is modeled in PSCAD/EMTDC, and various faults are simulated to verify the proposed method. Numerous simulation results indicate that the protection method is effective and immune to fault locations, fault resistances, and fault types.