Traction substation power supply system with three power supplies

The invention relates to a traction substation power supply system with three power supplies. The system comprises: a first system substation and a second system substation which are adjacently arranged along a railway; at least two first substations, wherein each first substation comprises a busbar A, a first traction transformer A and a second traction transformer A, the first traction transformer A and the second traction transformer A are electrically connected with the busbar A, and the busbars A are led to the first system substations through two paths of first power lines; at least twosecond substations, wherein each second substation comprises a busbar B, a first traction transformer B and a second traction transformer B, the first traction transformer B and the second traction transformer B are electrically connected with the busbar B, and the busbars B are led to the second system substation through two path of power lines B; and a power connection line electrically connected between the busbar A ad