Automatic generation control using two degree of freedom fractional order PID controller

In this paper, Two-Degree-of-Freedom-Fractional Order PID (2-DOF-FOPID) controller is proposed for automatic generation control (AGC) of power systems. Proposed controller is tested for the first time on a three unequal area thermal systems considering reheat turbines and appropriate generation rate constraints (GRCs). The simultaneous optimization of several parameters of the controllers and speed regulation parameter (R) of the governors is done by a recently developed metaheuristic nature-inspired algorithm known as Firefly Algorithm (FA). Investigation clearly reveals the superiority of the 2-DOF-FOPID controller in terms of settling time and reduced oscillations. Present work also explores the effectiveness of the Firefly algorithm based optimization technique in finding the optimal parameters of the controller and selection of R parameter. Further, the convergence characteristics of the FA are compared to justify its efficiency with other well established optimization technique such as PSO, BFO and ABC. Sensitivity analysis confirms the robustness of the 2-DOF-FOPID controller for different loading conditions and wide changes in inertia constant (H) parameter. Furthermore, the performance of proposed controller is tested against higher degree of perturbation and random load pattern. (C) 2014 Elsevier Ltd. All rights reserved.