Provided is a fault identification and protection method of an electrified railway AT traction network. When network
voltage is lower than a specified value, labeling no-load trend symbol values of the near ends and the far ends of a touch net T and a negative feeder F in each self-
coupling segment with 0, labeling influent trend symbol values with 1, labeling
effluent trend symbol values with -1, if an absolute value of a sum of the trend symbol values of two ends of the touch net T in each self-
coupling segment is larger than or equal to 1, or a failure absolute value of a sum of the trend symbol values of two ends of the negative feeder F is larger than or equal to 1, or a failure absolute value of a sum of the trend symbol values of two ends of a touch net T
branch and a negative feeder F
branch is larger than or equal to 1, respectively judging the touch net T to be in
short circuit failure to the ground, or the negative feeder F to be in
short circuit failure to the ground, or the touch net T to be in
short circuit failure to the negative feeder F, and breaking off all breakers at two ends of each self-
coupling segment. Short-circuit
reactance calculated according to corresponding
voltage and short-circuit current at two ends of each self-coupling segment and the corresponding length of the self-coupling segment determine failure positions.