Future DC Railway Electrification System - Go for 9 kV

Recently, the potential of medium voltage DC (MVDC) railway electrification has been highlighted in the literature. Currently, classical DC electrification systems reach their limits and it is not possible to operate locomotives at their nominal ratings or to increase traffic. Thus, this paper proposes a strategy for changing the railway electrification system from 1.5 kV DC to 9 kV DC. A method with an intermediate electrification system, keeping a 1.5 kV voltage for the overhead line and using a 9 kV feed-wire is proposed. In order to validate the proposed solution a real case study on the French Railway network is considered. Finally, the 1.5 kV DC and 9 kV DC electrification systems are compared in terms of efficiency and copper saving.