A novel configuration of unified power flow controller

This paper presents a novel configuration of unified power flow controller (UPFC). The proposed configuration has two inverters connected face-to-face on the AC side instead of connected back-to-back through a common DC link. The new configuration has the following advantages: 1) there is no active power exchange between the two inverters and both inverters only provide or absorb reactive power; 2) cascade multilevel inverters can be used in this configuration, thus eliminating the conventional magnetic interface-zigzag transformers, and greatly reducing power losses; 3) the total required VA rating of the inverters can be reduced greatly over a wide load conditions; and 4) The new configuration with modular cascade multilevel inverters and their redundancy has greater flexibility to system design and realization of higher reliability.