Power Flow Simulation of DC Railway Power Supply Systems with Regenerative Braking

The energy efficiency of a railway electrification system can be improved by the recovery of regenerative braking energy which is converted from the mechanical energy of braking trains. In a direct current (DC) railway power supply system, the regenerated energy which would otherwise be dissipated as heat in braking resistors may be consumed by surrounding accelerating trains, stored by energy storage systems, or fed back to upstream alternative current (AC) sides via reversible substations (RSS). It is necessary to evaluate the benefits related to energy savings achieved by the installation of RSS due to the high cost of initial investment. This paper models DC railway power supply systems in Simulink to simulate power flows within the systems in different scenarios with or without the deployment of RSS. Pantograph voltages of trains and power exchange between AC and DC sides are analysed to illustrate the effectiveness of the developed models and the limits on the braking energy recovery.