An Energy Function-Based Optimal Control Strategy for Output Stabilization of Integrated DFIG-Flywheel Energy Storage System

This paper presents an energy function-based optimal control strategy for output stabilization of integrated doubly fed induction generator (DFIG)-flywheel energy storage architecture to keep the grid power isolated from wind power output and voltage fluctuations and thus enabling increased penetration of wind energy resources. First, a grid connected two mass DFIG and a grid supportive single mass squirrel cage induction generator-based flywheel energy storage system model have been considered for controller design and proof of concept exploration. Second, a new energy function-based control architecture is proposed for maximum energy transfer from wind farm during normal operation and to improve DFIG low voltage ride through characteristics. It has been observed that the proposed architecture is very effective in mitigating oscillations and thus increasing wind energy penetration.