This paper proposes an active-damping method to improve the dynamic performance of multiple grid-tied virtual synchronous generators (VSGs) in a power plant. The authors analyze the damping ratio of multiple VSGs in parallel using Lyapunov's indirect method, revealing that the system can be poorly damped across a wide range of inertia and damping settings. To address this, they develop self-damping and mutual-damping controllers to suppress self- and mutually induced low-frequency power oscillations, respectively. An adaptive tuning algorithm is proposed for practical implementation, enabling automatic realization. The effectiveness of the proposed method is validated through simulations in Digsilent/PowerFactory and experiments, demonstrating improved damping ratios, enhanced inertial response, and reduced power oscillations under various disturbances. The method also shows robustness against variations in grid impedance and communication delays. The paper contributes to the literature by providing a comprehensive solution for multiple VSGs, addressing both self-induced and mutual-induced oscillations, and enhancing the overall stability and performance of the power plant.This paper proposes an active-damping method to improve the dynamic performance of multiple grid-tied virtual synchronous generators (VSGs) in a power plant. The authors analyze the damping ratio of multiple VSGs in parallel using Lyapunov's indirect method, revealing that the system can be poorly damped across a wide range of inertia and damping settings. To address this, they develop self-damping and mutual-damping controllers to suppress self- and mutually induced low-frequency power oscillations, respectively. An adaptive tuning algorithm is proposed for practical implementation, enabling automatic realization. The effectiveness of the proposed method is validated through simulations in Digsilent/PowerFactory and experiments, demonstrating improved damping ratios, enhanced inertial response, and reduced power oscillations under various disturbances. The method also shows robustness against variations in grid impedance and communication delays. The paper contributes to the literature by providing a comprehensive solution for multiple VSGs, addressing both self-induced and mutual-induced oscillations, and enhancing the overall stability and performance of the power plant.