Optimization research on hybrid energy storage system of high-speed railway

The regenerative braking energy generated during the braking of high-speed trains affects the power quality of the power grid. Recovery of regenerative braking energy is problem that needs to be solved urgently. The regenerative braking energy of high-speed railway features high power and high energy. It is difficult to recover it only by using high power density supercapacitors or high energy density batteries. In this paper, a hybrid energy storage system (HESS) composed of supercapacitors and lithium-ion batteries and its optimal configuration method are proposed for the purpose of obtaining maximum economic benefits for railroad systems. Then the economic benefits when using the HESS and the single energy storage system are compared from the perspective of whether the regenerative braking energy is fully recycled or not. Finally, a simulation analysis with actual load of a high-speed railway station is performed. The highest benefit is achieved when the regenerative braking energy is partially recovered by the HESS, which can save 3% of the total cost per day and pay back the cost in eight years.