This paper proposes a longitudinal protection scheme utilizing empirical wavelet transform (EWT) for a through- type cophase traction direct power supply system

where both sides of a traction network line exhibit a distinctive boundary structure. This approach capitalizes on the boundary’s capacity to attenuate the high-frequency component of fault signals

resulting in a variation in the high-frequency transient energy ratio when faults occur inside or outside the line. During internal line faults

the high-frequency transient energy at the checkpoints located at both ends surpasses that of its neighboring lines. Conversely

for faults external to the line

the energy is lower compared to adjacent lines. EWT is employed to decompose the collected fault current signals

allowing access to the high-frequency transient energy. The longitudinal protection for the traction network line is established based on disparities between both ends of the traction network line and the high-frequency transient energy on either side of the boundary. Moreover

simulation verification through experimental results demonstrates the effectiveness of the proposed protection scheme across various initial fault angles

distances to faults

and fault transition resistances.