Research On Control Strategy Of Flywheel Energy Storage Array System Based On Active Disturbance Rejection Control

In recent years,wind power technology has become increasingly sophisticated and production costs have significantly decreased,allowing wind turbines to achieve large-scale grid-connected operation.However,due to the fluctuation and intermittency of wind energy,wind turbines cannot continuously provide power to the grid,which can have an adverse effect on the stability of the power grid.Flywheel energy storage systems have advantages such as fast response speed,high power density,and long service life,making them suitable for applications in the power system and other fields.This article focuses on the flywheel energy storage array system’s machine/grid-side converters and uses self-disturbance control technology to study the control strategy for high-voltage transients during system charging and discharging and grid voltage symmetry faults.The study solves the problems of slow system response,insufficient disturbance resistance,and unstable DC bus voltage in traditional control strategies.Firstly,the article provides an overview of the flywheel energy storage system’s unit structure and working principle,summarizing the system’s three operational modes.The article establishes the mathematical model of the motor in the flywheel energy storage system in different coordinate systems,laying the model foundation for the subsequent control of charging and discharging of the flywheel energy storage system and the highvoltage transient control of the flywheel energy storage array system.The article also analyzes the primary control modes of the flywheel energy storage motor,including vector control,direct torque control,and variable voltage variable frequency control.Secondly,the article points out that the traditional control strategy for flywheel energy storage systems has problems such as slow response speed,insufficient disturbance resistance,and poor DC bus voltage stability.Therefore,the article proposes a flywheel energy storage system’s charging and discharging control strategy based on improved selfdisturbance control technology.In this strategy,the machine-side converter control adopts a speed outer loop and current inner loop control strategy,optimizes and improves the nonlinear functions in the self-disturbance controller,replaces the traditional PI controller with the improved self-disturbance controller,and introduces a sliding mode observer to observe the motor’s speed and rotor position angle,verifying that the improved control system has faster response speed and stronger disturbance resistance.In the grid-side control of the flywheel energy storage system,the grid-side converter model is transformed into a second-order system.A second-order linear self-disturbance controller replaces the PI controller of the DC bus voltage outer loop.The improved control system can more effectively maintain the stability of the DC bus voltage.Simulation experiments show that the improved control strategy can effectively shorten the charging and discharging time of the flywheel energy storage system and improve the system’s stability.Finally,to address the problem of high-voltage faults of varying degrees in the power grid,the article proposes a method based on the coordinated control of improved flywheel energy storage array system’s machine/grid-side converters to achieve high-voltage transients.The flywheel energy storage array system adopts equal torque charging control strategy to absorb excess energy from the grid.The upper-level controller serves as the overall control unit,and the lower-level controllers drive each flywheel energy storage unit to charge according to the electromagnetic torque command value.The machine-side converter uses a DC bus voltage outer loop control strategy based on improved selfdisturbance control technology.The inner current reference value is adjusted considering factors such as DC bus voltage,load current,and rotor speed.The grid-side converter limits the maximum current while providing reactive support to the power grid according to the reactive power compensation principle.Simulation results verify the feasibility of this strategy.