© 2014 IEEE. A fully distributed control scheme of island ac microgrids that can perform the primary, secondary, and tertiary control locally in distributed generators (DGs) is proposed. In the control scheme, no central controller or external information exchange is needed, while the final frequency can be controlled within the allowable range and the DGs can share loads according to their increment costs. The low-pass filters are designed to decouple the dynamics of the microgrid and to improve the system performance. Simulation studies verify the effectiveness of the control scheme.