An optimal fractional order controller for an AVR system using particle swarm optimization algorithm

Application of Fractional Order PID (FOPID) controller to an Automatic Voltage Regulator (AVR) is presented and studied in this paper. An FOPID is a PID whose derivative and integral orders are fractional numbers rather than integers. Design stage of such a controller consists of determining five parameters. This paper employs Particle Swarm Optimization (PSO) algorithm to carry out the aforementioned design procedure. A novel cost function is defined to facilitate the control strategy over both the time-domain and the frequency-domain specifications. Comparisons are made with a PID controller from standpoints of transient response, robustness and disturbance rejection characteristics. It is shown that the proposed FOPID controller can improve the performance of the AVR in all the three respects.