Power systems are generally required to operate near their maximum capacity. Thus, there is an increased focus on improving real power system capacities through the installation of novel devices, including the Flexible AC Transmission Systems (FACTs). This paper discusses the optimal incorporation of thyristor-controlled series capacitor (TCSC) in the 400 kV Baghdad grid of the Iraqi network as a suggested method to control the power transfer of a transmission line (TL) and suppress Sub-Synchronous Resonance (SSR). The MATLAB 2019 simulation is executed utilizing the phase angle as an index to select an appropriate TCSC location. Nine places were chosen based on eigenvalues, and three suitable places were determined, where 0.5< Xc/Xl <2. The Baghdad city 400 kV is examined by applying PSS/E 34 software with the series TCSC connected at each of the three selected locations, thus three distinct cases are studied. The results reveal that the TCSC connection between 16428 4BGE and 16419 4BGS, where the value of (Xc/Xl) =1.46, was the optimal place where the series TCSC connection is conducted. From the results, it can be concluded that the least Xc/Xl value indicates the better the control of frequency and voltage, as well as the power losses in TLs reduction are higher.
