Fixed energy storage technology applied for DC electrified railway (traction power substation)

The fixed energy storage system solves the problem of rising energy costs by reducing primary energy consumption. Without a fixed energy storage system, the energy generated by a breaking vehicle would be simply converted into waste heat by its breaking resistors if no other vehicles are powered simultaneously. Because, as a rule, such synchronization of breaking and powering cannot be coordinated, the energy storage system stores the energy generated during braking and discharges it again when a vehicle is powered. This greatly reduces primary energy demand in traction power substation. However, in addition to this energy saving, the energy storage system contributes to the reduction of CO₂ emissions. The energy storage system also stabilizes the system voltage. This study introduces technologies of fixed energy storage system applicable for DC electrified railway in Japan, and describes new control method for energy storage system.