AC or DC grid for railway stations?

The energy consumption of urban railway stations is very large and ever increasing. To reduce the national electrical grid consumption, the first step is optimizing the equipment size and the second step is adding other available electrical sources like the train residual braking energy. Many of local energies productions use Direct Current (DC. The actual internal station grid is in Alternative Current (AC) but the majority of the equipment has an AC/DC converter to be supplied in DC. This paper describes the project led by Efficacity Institute, which addresses the use of additional existing energies and to develop a more adapted station grid to reducing the daily energy consumption peak. One Efficacity energetic concept aims to store the braking energy of the trains with a stationary electrical saving system. This energy is integrated to the power supply of a railway station thanks to a microgrid. First step of this microgrid are studied in this paper to develop the more adapted grid structure.