A Constant Power Discharge Strategy for Flywheel Energy Storage System Based on Maximum Torque Per Ampere

Flywheel energy storage system (FESS) possesses advantages such as rapid response, high frequency operation, and long lifespan, making it widely used in grid frequency regulation and uninterrupted power supply. To maintain a stable DC bus voltage during the discharge phase, FESS typically employs an outer-loop DC voltage control on the machine-side converter. However, this control method fails to meet the power response requirements for grid frequency regulation. This study introduces a control strategy that combines outer loop power control with Maximum Torque per Ampere (MTPA) control on the machine-side converter. This approach not only meets the power response requirements but also increases the depth of discharge, thereby fulfilling the needs of grid frequency regulation. Additionally, the grid-side converter utilizes outer loop DC voltage control to ensure DC bus voltage stabilization. The effectiveness of this control strategy is validated through simulation results.