Decentralized Fractional Order PID Controller for AGC in a Multi Area Deregulated power system

This paper presents the application of Fractional Order PID controller as a supplementary controller to improve the dynamics of LFC in multi area deregulated power system. FOPID is a PID controller whose derivative and integral orders are of fractional rather than integer. The extension of derivative and integration order from integer to fractional order provides more flexibility in design of the controller, thereby controlling the wide range of dynamics of a system. Using ITAE as performance criteria to be optimize, the FOPID controller parameters: proportional (Kp), Integral (Ki), Derivative (Kd), integral order (λ), and the derivative order (μ) operators are optimized using Evolutionary Real coded Genetic Algorithm (GA) and Firefly algorithm (FA) as a hybrid algorithm (GA-FA). The feasibility and robustness of the controller is investigated on a three-area interconnected power system consisting of Thermal-Thermal unit in areaI, Hydro-Thermal unit in the area-II and Thermal-Gas unit in area-III. The dynamics of frequency deviations and tie-line power deviations were investigated by considering the possible contracts between various GENCOs and DISCOs of multi area deregulated power system using DISCO participation matrix (DPM). The simulation results show the proposed FOPID controller tuned by the proposed Hybrid Genetic-Firefly algorithm (GA-FA) exhibits improved dynamic performance over conventional PID controller.