Energy benefits from bidirectional electrical substations in metro railway systems

The present paper studies the impact of an energy return system for efficient management of regeneration in modern metro railway networks. This system will be capable of returning the regenerated train braking energy from the metro network to the 20kV distribution grid that is otherwise wasted in on-board braking resistors in the form of power losses (heat). Train performance simulations were performed at 90sec, 150sec and 300sec headways and the returned energy was quantified. The voltage threshold for feeding back the energy to the distribution grid was selected at 800V and the energy and cost impact was assessed, proving a viable energy return system for implementation.