Microgrids are eco-friendly power systems because they use renewable sources

such as solar and wind power as the main power source. However, the stochastic nature of

wind and solar power is a considerable challenge for the efficient operation of microgrids.

Microgrid operations have to satisfy quality requirements in terms of the frequency and

voltage. To overcome these problems, energy storage systems for short- and long-term

storage are used with microgrids. Recently, the use of short-term energy storage systems

such as flywheels has attracted significant interest as a potential solution to this problem.

Conventional flywheel energy storage systems exhibit only one control mode during operation:

either smoothing wind power control or frequency control. In this paper, we propose a new

flywheel energy storage system based on a doubly fed induction machine and a battery for

use with microgrids.