Design of UPFC Controller Using Modified Bilinear Equation for Improving Transient Stability

Based on the use of the modified bilinear equation for the unified power flow controller (UPFC), this paper proposes a new control strategy to improve the transient stability of power system. This control strategy is applied to shunt and series inverters of UPFC as the modulating signals at the operating point. This input signals are such that the derivative of Liapunov energy function is negative definite. Simulation results show that the transient stability of power system has improved more effectively than the conventional PI controllers. Moreover, the coordination between series and shunt controllers of UPFC via one control law is considered as the main advantages of the designed controllers.