Control Strategy of Flywheel Energy Storage Array for Urban Rail Transit

The introduction of a flywheel energy storage system in the urban rail transit power supply system can effectively recover the regenerative braking energy of the train and stabilize the DC catenary voltage. However, the single flywheel energy storage system has a small capacity, and it is difficult to meet the demand for train regenerative braking energy utilization. Flywheel energy storage array is an effective means to solve this problem, however, there are few researches on its control strategy. This paper first analyzed the mathematical model and operating characteristics of the flywheel energy storage system. Then, considering the requirements for voltage stabilization, energy saving and field weakening, a control strategy for a single flywheel energy storage system based on multiple voltage thresholds was given. Subsequently, aiming at the core issues of flywheel array speed-balance control and SOC management, two flywheel energy storage array control strategies based on speed-error regulation control and based on "voltage-speed-current" three closed-loop control were proposed. Finally, the simulation and experiment verify that the proposed control strategy can be arrayed. © 2021, Electrical Technology Press Co. Ltd. All right reserved.