Design of Power System Stabilizer Using Phase Based Objective Function and Heuristic Algorithm

This paper proposes a novel objective function based on power system exciter frequency response to design robust power system stabilizer (PSS) using heuristic optimization techniques, in order to damp the electromechanical oscillations at very low frequencies (0.1-3 Hz), that often tend to grow with time and cause system instability. The new objective function comes from the fact that the generated electrical torque must be in phase with the rotor speed deviation in order to get the optimal damping, thus by considering the arithmetic summation of the exciter and the PSS phases to be approximately zero in the desired frequency range, a new objective function can be defined. A Single Machine Infinite Bus (SMIB) system is considered in this study and the conventional lead-lag controller is designed based on the new objective function and Differential Evolution optimization algorithm. Several excitation and PSS models are simulated to test the effectiveness of the proposed method which is found to be satisfactory.