AbstractStand‐alone power systems (SPS) are attracting more and more interest with the global move toward distributed generation (DG). Without strong support from the power grid, they suffer from poor load‐following capability at varying loads. A cache power that has fast response and high energy efficiency is demanded. As a solution, this paper provides an AC power technology based on flywheel energy storage. Different from the other DC generation technologies such as electric double layer capacitor (EDLC) or superconducting magnetic energy storage (SMES), the proposed flywheel system generates AC power and therefore can be directly connected to the power line without any power semiconductors. Furthermore, the proposed technology realizes power in/out automatically in response to the frequency/voltage variation of the power line. Therefore, this system has the advantages of robustness, simplicity, and fast response. Besides, by getting rid of power semiconductors, the proposed flywheel system has a good overload capability as high as two to three times. We prove by simulation and experimentation the validity and effectiveness of the proposed technology to provide cache power for stand‐alone power systems. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.