Vehicle-to-Grid (V2G) as line-side energy storage for support of DC-powered electric railway systems

Two predominant areas of ongoing transport electrification are the uptake of electric vehicles (EVs) in personal transportation and electrically powered trains for mass transportation - both significantly increase demand stresses on the electric power grid. In this research, a novel V2G application to support electrically powered rail transport is proposed. A local V2G network can reduce peak demand stresses on the power grid arising from electrified rail traffic and enable brake energy recovery from DC-powered electric trains. A case study examining an existing third-rail DC-powered rail system in England supported by a simulated population of aggregated parked EVs is presented. Simulation results for 24 h of V2G supported rail traffic from the view of a single train station with nearby V2G enabled car park are discussed. Therein the EV population size, charging rate limits per EV and the overall power made available from the power grid are variables. The V2G network's ability to absorb power from regenerative braking on the rail system was found to be more sensitive to changes in EV charging rates than its ability to provide traction power. In particular, careful power management is required to avoid charging EVs ‘too quickly’ during periods without rail traffic.