Active damper is a promising solution to address the stability issues caused by the interaction between the parallel grid-connected converters, which are the results from the coupled grid impedance. To futher improve that, this paper proposes a series active damper that using a virtual damping resistance through detection and resonant controller, the series active damper can suppress the resonance with its external damping character in closed-loop damping character are carried out. Simulation and experimental results are presented to verify the effectiveness of the proposed series active damper.