Frequency Domain Design of Fractional Order PID Controller for AVR System Using Chaotic Multi-objective Optimization

A fractional order (FO) PID or FOPID controller is designed for an Automatic Voltage Regulator (AVR) system with the consideration of contradictory performance objectives. An improved evolutionary Nondominated Sorting Genetic Algorithm (NSGA-II), augmented with a chaotic Henon map is used for the multiobjective optimization based design procedure. The Henon map as the random number generator outper forms the original NSGA-II algorithm and its Logisti c map assisted version for obtaining a better design trade-off with an FOPID controller. The Pareto fronts showing the trade-offs between the different design objectives have also been shown for both the FOPID controller and the conventional PID controll er to enunciate the relative mer its and deme rits of each. The design is done in frequency domain and hence stability and robustness of the design is automatically guaranteed unlike the other time domain optimization based controller design methods. Crown Copyright 2013 Published by Elsevier Ltd. All rights reserved.