A Decentralized Frequency Modulation Method for Cascaded H-Bridge PV Systems Based on VSG and Virtual Resistance Algorithm

In this paper, a decentralized frequency modulation method based on VSG and virtual resistance is proposed to improve the frequency support capability of cascaded H-bridge (CHB) photovoltaic (PV) systems. This method makes the PV unit work at the standby power point, reserve certain power for frequency modulation function, and realize dynamic active power control only according to the local information, so as to realize the distributed frequency modulation of the PV system. Compared with the traditional centralized control frequency modulation method, this method has higher reliability, stability, and flexibility. Simulation results show that the proposed method can significantly improve the frequency response capability of grid-connected CHB PV systems.