Frequency Control Strategy of Grid-connected PV System Using Virtual Synchronous Generator

Photovoltaic (PV) power generation has broad prospects as one of the renewable generations, and its penetration in the power grid keeps increasing. However, PV system does not have the advantages of large inertia and output impedance as synchronous generators, and cannot realize active frequency regulation in real time. Some scholars have proposed a droop control algorithm based on the self-droop characteristics of synchronous generators, which makes the PV system have the primary frequency regulation capability, but it still lacks inertia and damping links in the control process. To solve this problem, in this paper, a frequency control strategy for PV system using virtual synchronous generator (VSG) control is proposed. Based on droop control, the swing equation is added to improve the dynamic characteristics of PV system during frequency control. Simulation results verified that the proposed algorithm can achieve the same primary frequency regulation capability as the droop control, and also effectively improve the dynamic characteristics of frequency change.