Review of Energy Storage Devices in DC Electric Rail Transit Systems: Technologies, Applications and Energy Management Control Strategies

The electric rail transport sector is the largest consumer of energy. It is divided into 70% for traction and 30% for station consumers. So, there is a need to implement effective solutions to reduce its consumption and carbon emissions. Most energy optimization strategies concentrate on the effective management of regenerative electric braking energy recovery and storage in transit systems using DC electric rail. During regenerative braking, traction motors react as generators and return part of the kinetic energy as electrical energy, much of which is lost as heat to avoid power surges. Thanks to this strategy, this energy is used either by returning it to the electricity grid or storing it in energy storage systems for later use. The aim of the work has been to provide an overview of the three main regenerative braking energy storage devices most commonly used in railway systems: batteries, supercapacitors, and flywheels. Moreover, their applications in storage systems, their classifications, and the advantages and disadvantages of each are discussed. A brief discussion of energy management and control techniques for energy storage systems.