Fuzzy Self-tuning Fractional Order PID Controller Design in Load Frequency Control of Power Systems

the aim of this paper is to control for the power system frequency oscillations between interconnected power systems. The first controller used in this study is a fractional order PID (FOPID) controller for load frequency control (LFC) of a single area power system and a three area electrical interconnected power system. For the FOPID controller, besides the proportional, integral and derivative gains Kp, Ki, Kd, there are two more adjustable orders: as the powers of s in integral and derivative actions, viz. $\lambda$ and $\mu$ respectively. The optimal values of the FOPID (OFOPID) controller parameters (gains and orders) obtained by using Self-adaptive Global Harmony Search (SGHS) technique with an Integral Time Absolute Error (ITAE) objective function. The second controller in this paper is a fuzzy self-tuning optimal FOPID (STOFOPID) controller. The SGHS technique] used to obtain the optimal normalizing gain values of STOFOPID controller. The LFC of the power system investigated with the OFOPID and STOFOPID controllers to improve the frequency oscillation damping in power system. The STOFOPID controller has limited the frequency deviations effectively as compared to OFOPID controllers under different operating conditions, various parameters and various loads in linear and nonlinear power systems. The results carried out using MATLAB/Simulink software.