This document provides a review of distributed FACTS (D-FACTS) controllers, specifically the Enhanced Power Flow Controller (EPFC). The EPFC is a D-FACTS controller that functions similarly to a thyristor controlled series compensator (TCSC) but is distributed along transmission lines in small modules every 5-10 km. D-FACTS controllers offer advantages over conventional FACTS devices by being more cost effective, reliable, and not requiring breaks in transmission lines for installation. The EPFC works by injecting series impedance into lines using single turn transformers to control power flow without significantly increasing costs or complexity compared to traditional FACTS controllers.