An improved discharge control strategy with load current and rotor speed compensation for High-Speed Flywheel Energy Storage System

摘要

This paper proposes an improved discharge control strategy with load current and rotor speed compensation to suppress the fluctuation of DC bus voltage in High-speed Flywheel Energy Storage System (FESS). Mathematical model of FESS is built at first and conventional discharge control strategy with pure PI controller is analyzed. Then a load current and rotor speed compensation module is added to the outer DC bus voltage loop to recalculate the reference value of q-axis current with the DC bus voltage, load current, rotor speed and motor flux considered. In addition, feedforward decoupling strategy is utilized in the inner-current-loop to realize the independent control of the d-axis and q-axis currents. Simulation results with MATLAB/Simulink verify the proposed strategy improves the tracking capability of the d-q axis current, accelerates the DC bus voltage recovery speed and eliminates the fluctuation of the DC bus voltage caused by abrupt change of load current.