SUMMARY
Over the past two decades, developing distributed energy sources in electric power grid have created new challenges related to the power quality, voltage adjustment and proficient energy utilization. Power electronic converters are widely used to interface the emerging energy systems (without and with energy storage) and smart buildings with the transmission and distribution systems. Flexible Ac Transmission Systems (FACTS) and Voltage-Source Converters (VSC), with smart dynamic controllers, are emerging as stabilization and power filtering equipment to improve the power quality. FACTS devices are of vital significance for tackling the problem of voltage instability which is inevitable and leads to losses in transmission system networks. These devices provide fast voltage regulation, ensure system stability and reactive power compensation. In this regard, modeling, control and appropriate placement of these devices in the transmission lines have been of great importance for researchers of power transmission systems. By using high speed power electronic converters, FACTS perform many times faster than the conventional compensation techniques. FACTS not only provide fast voltage regulation but also damping of active power oscillations and reactive power compensation. Hence, they increase the availability and reliability of the power systems. But, the functioning of a FACTS device extremely reckons upon its parametric quantity, appropriate placement, and sizing in the power network. In this paper, an extensive literature survey is presented to discuss and investigate these parameters of FACTS devices.