LAUSR

The installation of a stationary supercapacitor energy storage system in urban railway systems effectively improves the energy saving rate by means of recycling the train's regenerative braking energy. In this paper, a hierarchical control strategy, which consists of an energy management layer and a converter control layer, is proposed. In the energy management layer, the energy management state machine is introduced. In the converter control layer, based on the double closed-loop proportional-integral (PI) control strategy, a multiobjective optimization algorithm for the outer voltage loop is proposed, which optimizes the control parameters at each operating point, comprehensively considering undershoot suppression, rapidity, and antidisturbance performance of the system. The proposed control strategy is validated through simulation and laboratory experiment, and finally, applied in the Megawatt-level energy storage device of Beijing Batong Line.