The object of this work is to improve the stability of the Iraqi National Super Grid System (INSGS) by installing Unified Power Flow Controller (UPFC) devices in different optimal locations under fault condition and comparing the results with those of without FACTS under the same condition.The optimal location of the FACTS device was specified based on Genetic Algorithm (GA) optimization method, it was utilized to search for optimum FACT parameters setting and location based objective function that depends on the power and voltage as a fitness constraints.MATLAB was used for running both the GA program and Power System Analysis Toolbox (PSAT) as Graphical User Interface, Newton Raphson method also used for solving the load flow of the system and the Trapezoidal method for the non-linear differential equations.The system that has been implemented is INSGS 11-machine, 24-bus, 39 (400kV) overhead transmission lines.The GA program is applied for the Iraqi grid system which is complicated.The results obtained showed that the installation of UPFC devices at the optimal locations of the Iraqi grid gives an improvement in the stability by damping the voltage and rotor angle oscillations after subjected to the three phase fault to ground at different locations and different cases (temporary fault, permanent fault).A comparison has been made between these different cases based on the durations of the tested faults, and with the UPFC devices installed in the system, it can remain stable for longer time than without UPFC during fault condition.