A Decentralized Self-synchronizing Method for Cascaded Converter System Based on Analysis of the Existence of Equilibrium Points

As for the Cascaded Converter System (CCS), the existing grid-connected self-synchronization control methods are sensitive to grid fluctuations. which will affect the system stability and may lead to issues about the existence of equilibrium points of the system. To address these issues, this paper analyzes the impact of grid voltage fluctuation on the existence of system equilibrium points. A robust decentralized self-synchronizing control method is proposed, where a voltage correction mechanism is designed to guarantee the system's equilibrium points. Besides ensuring frequency self-synchronization, the flexible adjustment abilities of output power and power factor are greatly improved. The control-hardware-in-loop (CHIL) and RTU-BOX-based experiment results under grid voltage fluctuation and load changing show that the system has good disturbance rejection capability and robust performance.