FACTS devices help to better stabilise the power systems. They are power electronic devices installed to increase
stability of system post any disturbance. Control laws are applied to these existing FACTS devices to improve the damping of
frequency oscillations. UPFC is used to damp the frequency oscillation. It can control the parameters of voltages, voltage angles
and line impedance and subsequently damp the electromechanical oscillations to improve transient stability. It is capable of
analysing and controlling all the factors that effect power flow in a transmission line like voltage and line impedance either
simultaneously or selectively
