Overvoltage Simulation Analysis and Protection Strategy of UPFC Series Transformer

The double loop structure control strategy of converters and the circulation current suppression strategy of converter were studied. An electromagnetic transient model is built on PSCAD/EMTDC simulation. AC bus voltage/DC voltage injection control and direct voltage control for UPFC were implemented in this model. Research on the fault characteristics of UPFC and the influence on the AC system under typical station faults. Single-phase ground fault of AC bus and single-phase ground fault of AC line of the series transformer were theoretically analyzed and verified by simulation. the overvoltage of the series winding of the series transformer when the fault occurs on the grid side was obtained. Finally, the series transformer overvoltage protection scheme and anti-misjudgment logic are given.