The dynamic frequency characteristic of Virtual synchronous generator (VSG) systems is more complicated due to the coupled interaction of line impedance, virtual inertia, and damping coefficient in parallel VSG systems. In this chapter, a systematic analysis of the influence of virtual inertia and damping coefficient on the dynamic frequency characteristic among parallel VSG systems was presented, and a coordinated control for virtual inertia and damping was proposed to improve frequency stability and achieve a better dynamic performance of parallel VSG systems. The effectiveness and superiority of the proposed method were verified by simulation and experimental results.