Verification of a Power Storage System Using Electric Double Layer Capacitors (EDLCs)

Yoshinobu NAKAMICHI, Dr. Eng.
General Manager,
Power Supply Technology Div.

    Interest has been shown in the concept of a power storage system aimed at leveling load and improving energy efficiency by charging during vehicle regeneration and discharging during running. Such a system represents an efficient countermeasure against pantograph point voltage drop, power load fluctuation and regenerative power loss. The Railway Technical Research Institute (RTRI) selected EDLCs as power storage media and a step-up/step-down chopper as a power converter to exchange power between the storage media and overhead lines. Basic verification was conducted using a mini-model for 400V DC, demonstrating characteristics suitable for its use as a power storage system.

    Based on these results, a power storage system was built for 600V DC and a verification test conducted in conjunction with the Enoshima Electric Railway Co. Ltd. The power storage system was installed indoors between two DC substations at the Gokurakuji car inspection section, as shown in Figure 1. The storage system shown in Figure 2 was set to discharge power when overhead line voltage drops below a preset level, and charged by both substations when power in the storage system decreases. The test showed that the storage system compensated the voltage of the overhead lines, as shown in Figure 3. Research for practical use of the system in 1500V DC sections will begin immediately.

    This study was conducted with a subsidy from the Ministry of Land, Infrastructure and Transport.