In this paper, the authors have discussed about the study of Distributed Flexible AC Transmission System (D-FACTS) devices in power system by controlling AT&C losses. D-FACTS devices offer many potential benefits to power system operations. Modern power systems are continuously being expanded and upgraded to cater the need of ever growing power demand. This is a review paper to analyze the current trends in FACTS and D-FACTS to improve the performance of existing power system performance. D-FACTS devices are applied to minimizing real power losses and controlling system voltages after they have become too high.