3. Dynamic Frequency Regulation Via Adaptive Virtual Inertia

VSGs emulate the kinetic energy of SGs to support the islanded networks to maintain grid frequency. This chapter introduces a virtual synchronous generator (VSG) control based on adaptive virtual inertia to improve dynamic frequency regulation of microgrid. When the system frequency deviates from the nominal steady-state value, the adaptive inertia control can exhibit a large inertia to slow the dynamic process and thus improve frequency nadir. And when the system frequency starts to return, a small inertia is shaped to accelerate system dynamics with a quick transient process. As a result, this flexible inertia property combines the merits of large inertia and small inertia, which contributes to the improvement of dynamic frequency response. The stability of the algorithm is proved by Lyapunov stability theory, and the guidelines on the key control parameters are provided. Finally, both hardware-in-loop (HIL) results demonstrate the effectiveness of the control algorithm.