It is not possible to use the full capacity of the transmission lines due to voltage limitations and stability issues. Therefore, compensators must be used to improve the transmission line capacity. One of the suggested ways for this purpose is to use flexible alternating current transmission system (FACTS) devices in the power system. The various capabilities of the FACTS devices have made it possible to set different targets to determine their optimal location and position. Some of the most important placement targets include increasing voltage stability, improving voltage profiles, reducing losses, increasing line capacity limit and reducing fuel costs for power plants through optimal power distribution. In this paper, optimal locating o...