Improved Active Disturbance Rejection Control Strategy of Flywheel Energy Storage System in Rail Transit

The flywheel energy storage system (FESS) is considered to be an ideal choice for the energy recovery and utilization of regenerative braking in rail transit due to its high energy density, long life, fast response and environmental friendliness. The control of the flywheel energy storage system is a key part to ensure the stable and efficient operation of the system. In view of the limitations of the traditional PI controller in controlling the flywheel energy storage system, an improved Active Disturbance Rejection Control (ADRC) strategy was studied. Firstly, the cascaded nonlinear expansion state observer is used to enhance the estimation ability of the system to estimate the disturbance, and the control performance is improved. Then, considering the problem that there are many parameters in the nonlinear ADRC with unclear physical meaning and difficult to debug, combined with the advantages of the Sliding Mode Control (SMC) parameter with clear physical meaning, strong robustness and strong anti-disturbance ability, the Sliding Mode-Active Disturbance Rejection Control (SM-ADRC) is constructed to improve the control performance of the system. Secondly, in view of the complexity of the parameter setting of the SM-ADRC controller, the Particle Swarm Optimization (PSO) algorithm was used to tune the control parameters, which improved the efficiency of parameter tuning. Finally, the feasibility and effectiveness of the proposed control strategy in the charging and discharging conditions of flywheel energy storage system are verified by experiments.