The increasing number of distributed energy resources, energy storage systems and controllable loads, summarized as decentralized actors (DAs), causes new challenges for grid operation and planning. At the same time, it leads to new capabilities of forming microgrids (MGs) with controllable generation, consumption and storage functionalities in public distribution systems. To utilize MGs for ensuring grid stability in critical situations, necessary communication technologies are cost intensive and have to meet high security and reliability requirements. Modular microgrids (MMGs), which are decoupled from the upstream grid by power electronic grid interconnectors, offer the chance to use grid frequency as cost efficient and reliable communication channel. This paper presents a novel approach to control MMGs by frequency variation. To demonstrate the potential of the concept, the MMG with its DAs is modeled in DIgSILENT PowerFactory and simulation results are depicted.