Regenerative energy utilization in a.c. traction power supply system

To make railway transportation more efficient, utilization of recuperation energy in d.c. traction power supply system is actively discussed in Japan. We, East Japan Railway Company, have already introduced two Lithium ion battery systems at Haijima Substation since 2013 and at Okegawa Substation since 2014. They contribute to reduce total traction energy supply about 5-8%. In a.c. traction power supply system, on the other hand, it is rarely discussed to make use of recuperation power because it is not an issue compared with d.c. traction power supply system in many cases. We installed, however, RPC, railway static power conditioner, at Ushiku sectioning post for recuperation energy utilization in 2014. In this paper, the difference between d.c. traction power supply system and a.c. traction power supply system from the point of view to utilize recuperation energy and its future prospect in a.c. traction power supply system are discussed.