Research on Dynamic Voltage Characteristics of AC/DC Hybrid System Based on PET

Since power electronic transformers (PET) can effectively control the power quality of the system while enabling AC and DC equipment to be flexibly connected to the grid, the dynamic voltage characteristics of PET system under large disturbances is of great significance for improving the stability of the system operation and designing protection devices in such system. This paper analyzed the dynamic voltage characteristics of the ports under two typical large disturbance faults, based on the typical three-stage topology of PET and its control strategies. The results show that the state of 1900V voltage of the rectification stage output could be the key index of stability state of the AC/DC hybrid system based on PET. Finally, the Prony method is used to quantitatively evaluate the severity of the fault in the AC/DC hybrid system based on PET. The results could be the reference to the design of PET protection devices and the study of the stability of PET systems.