Abstract: This paper represents a new dimension of the Flexible AC Transmission System (FACTS) called as Distributed Power-Flow Controller (DPFC). The present paper describes the introduction and control of power in transmission line equipped with FACTS (DPFC) devices. Detailed simulations are carried out to illustrate the control features of DPFC and its influence to increase power transfer capability and improve system reliability. The DPFC is derived from the unified power -flow controller (UPFC) and DPFC has the same control capability as the UPFC. The DPFC can be considered as a UPFC with an eliminated common dc link. The active power exchange between the shunt and series converters, which is through the common dc link in the UPFC, is now through the transmission lines at the third -harmonic frequency.

Keywords: FACTS, Power Flow Controlling Devices, UPFC, DPFC, Active power Exchange, Third harmonics, D-Facts, Series control, Shunt control, Central control.