The main subject of these paper deals with enhancing the steady-state and dynamics performance of the power grids by using new idea namely Advanced Flexible AC Transmission Systems based on Evolutionary Computing Methods. Control of the electric power system can be achieved by using the new trends as Particle Swarm Optimization applied to this subject to enhance the characteristics of controller performance. This paper studies and analyzes Advanced Flexible AC Transmission System to mitigate only one of power quality problems is voltage swell. The Advanced Flexible AC Transmission System, which will be used in this paper, is the most promising one, which known as Advanced Thyristor Controlled Series Reactors, and Advanced Static VAR Compensator were utilized in this research to mitigate the voltage swell aiming to reach. This paper focuses on the operation of the AFACTS device under turning off heavy load that may causes transformer damaged, as no research covers this problem by this technique. Particle Swarm Optimization is used to determine the value of series inductor connected to the Advanced Flexible AC Transmission System. The proposed algorithm formatting, deriving, coding and programming the network equations required to link AFACTS during steady-state and dynamic behaviors to the power systems tested on the IEEE 30 bus system as well as IEEE 14 bus system, and 9 bus system.