Center of Inertia (COI) is introduced for solving complicated stability problems due to interactions among multi-grid-forming converters. But the calculation of COI frequency relies on global communication and a centralized controller, which results in high communication costs and complexity, and reduces the system reliability. This chapter proposes a distributed control method via COI frequency for multi-converters grids. The COI frequency estimator is designed based on dynamic consensus control. Communication between adjacent neighbors is required, which improves reliability and reduces communication costs. The stability of the proposed control method is proved and the feasible range of the control parameter is presented. Simulations and experiments are carried out to verify the effectiveness and feasibility.