Fuzzy logic controller for damping sub-synchronous oscillation in power system

Sub-synchronous oscillation occurs in frequency less than synchronous frequency, in transmission systems compensated by series capacitor and in a state of equilibrium of the system, it imposes great disturbance which brings about tortional modes with varied frequencies in the shaft of the generator which ultimately can result in fatigue in the shaft of the turbine-generator and even might result in fracture in the shaft with irrecoverable damages. To damp and to control the sub-synchronous oscillations, exciter voltage controller was employed in this study. In line with the improvement of this controller, fuzzy control method was used. The results of simulation confirm the effect of fuzzy controller optimization in this system.