Microgrid solutions for sustainable railway networks

The recent railway system has evolved into an extensive microgrid, constituting a complex framework along distributed active loads, origin and storage devices. In this context, the active load is embodied by the trains, while the sources encompass a microgrid reliant on renewable energies. A prevalent challenge faced by many electrical trains is the inability to recuperate energy during regenerative braking phases, coupled with extended charging times at stations. This paper proposes a techno-economic approach to address these challenges by introducing supercapacitors (SCs) for energy storage within the trains, aimed at reducing overall energy consumption. The designed railway station incorporates photovoltaic (PV) and fuel cell sources, along with batteries forming an energy storage system (ESS). SCs play a crucial role in the train's ESS, receiving power during braking phases and station stops through a pantograph integrated into an aerial power line. Supercapacitors are chosen for their high power characteristics, a substantial number of charge/discharge cycles, low specific energy and rapid charging capabilities. A power administration strategy is recommended to regulate the DC bus through voltage control and the buck-boost converter through current control. The sizing of the proportional-integral (PI) controller, essential for stabilizing the DC bus of both the train and station, is outlined. Design arrangement is meticulously modelled using MATLAB-Simulink.