Power system damping using fuzzy controlled unified power flow controller

The paper presents a design of a UPFC damping controller using two fuzzy logic schemes one based on Mamdani inference engine using the center of gravity method to find the controller output, and the second based on Takagi-Sugeno engine computing the controller output as linear combination of the inputs. Fuzzy control design is attractive for nonlinear systems application because it does not require a mathematical model, and it can cover a wide range of operating conditions. The advantages of the proposed controllers are their feasibility guaranteed by the use of a local measurement, which in this case is the tie line power flow, and their simplicity. The effectiveness of the controllers under dynamic conditions is illustrated thru nonlinear simulations of a two-area-four-machine power system. Simulations are carried out using the Power System Toolbox (PST).