Optimal motion of a rolling stock fleet under traction power system constraints

The operators of the railway industry (i.e., Traction System and Railway System Operators) are currently involved in a major process of energy transition. Aimed at improving both environmental sustainability and energy efficiency, technological infrastructures are being updated and new operating solutions studied. Moreover, the business opportunities offered by the new rail market are forcing operators to search for power quality solutions. In this paper, an efficiency strategy is proposed for optimally moving a fleet of trains while taking power quality indices into account. A method to relate the traction power requirements to the electrical variables of the railway infrastructure is formulated in terms of the power flow approach. Our numerical simulations focus on the real case of the Metro Line 1 in the southern Italian city of Naples. The energy problem of moving the trains on the track is solved by including a set of constraints at the point of common interaction between railway market operators. Specifically, repetitive train starts and their speed profiles are optimally managed in terms of power requirements at traction power substations by using power quality constraints. This strategy allows improvements in energy efficiency without compromising the quality of the railway service.