Flywheel energy storage system for traction applications

This paper describes the application of UPT´s unique world leading high-speed flywheel energy storage technology to real-time power management and voltage support for the traction industry. The flywheel system relies on technology developed over more than 30 years for URENCO´s high speed gas centrifuge and has itself undergone several further years of development. It is now the most advanced commercially available flywheel energy storage system. Its unique features, zero maintenance, 20 year life and high cyclic capability make it ideally suited to applications in rail power supplies. The flywheel system can resolve many of the problems encountered in traction supplies due to the ´peaky´ nature of the loads caused by trains accelerating and braking. In addition, the UPT system can provide energy savings by improving the system´s receptivity to energy from trains with regenerative braking. This paper describes how the system was applied to London Underground´s Piccadilly line for a trial application and presents some of the data from these tests. This successful trial has now led to the first commercial application with the New York City Transit Authority. Finally, the paper reviews some of the possible developments which may lead to the application of this technology to higher voltage systems.