A Novel Configuration of Unified Power Flow Controller

The paper proposes 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 the 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;4)The new configuration with modular cascade multilevel inverters and their redundancy has greater flexibility to system design and realization of higher reliability.The simulation results clearly show that the novel UPFC is feasible and advantageous over the conventional UPFC in terms of required VA rating.