Comparison of Energy Recovery Solutions on a Suburban DC Railway System

Conventional dc railway systems are usually supplied by nonreversible traction power substations. This means that regenerative braking energy cannot be sent back to the electric power grid. Therefore, this energy can only be sent to nearby consuming trains or be burned by the rheostatic or mechanical brakes. However, due to the low service frequency and the manual driving control in some suburban sections, trains synchronization is not always possible, and most of the braking energy is lost. Thus, there is great potential for energy recovery. This could be achieved with the addition of energy recovery devices. In this article, a dc railway system is modeled and simulated to compare the benefits of a reversible substation and two energy storage systems (wayside and onboard). Then, the model is validated with real measures taken on a French railway system. Finally, the simulation is used to compare the benefits of adding each device on a suburban section. Results show a reduction of up to 30% of the total supplied energy.