Nonlinear loads connected to electrical distribution networks are a source of harmonic pollution. These loads draw currents that contain varying levels of harmonic content, which do not contribute to useful active power because their frequencies do not match the grid voltage. To address the issue of harmonic current injection, one effective solution is the installation of series controllers in transmission lines. The Thyristor Controlled Series Capacitor (TCSC) represents a significant advancement in the management and optimization of power flow in electrical transmission networks. By integrating TCSCs into the grid, utilities can enhance the stability, capacity, and flexibility of power transmission systems. The core component of a TCSC is a series capacitor, which is partially bypassed by a thyristor-controlled reactor. This configuration allows for the dynamic adjustment of the capacitor's apparent reactance, thereby controlling the power flow through the transmission line with high precision and speed. Keywords:- FACTS Controller, Power Quality, TCSC, MATLAB.