Indian Journal of Science and Technology

Abstract

Background/Objectives: The main objective of this research work is to design a cascade control system with fractional order proportional plus integral controller as the primary controller and proportional controller as the secondary controller. The best optimal values for fractional order PI controller (FOPI) controller are obtained by minimizing time integral performance criteria i.e IAE using genetic algorithm. Methods/Statistical Analysis: Cascade control scheme is one of the most popular control schemes in process industries because of its improved disturbance rejection and easy implementation. Research have been done by various researchers in designing the conventional controller for a cascade control system, but the emergence of fractional calculus in the field of control area paved the idea to replace conventional integer order controllers by fractional order controllers. Findings: The cascade control system is always designed using conventional controllers. An attempt is made to replace conventional integer order controllers in the primary loop with fractional order controllers in order to improve the performance and get better disturbance rejection. Applications/ Improvements: Simulation results show the effectiveness of the proposed controller. The performance indices tabulated and compared to indicate the improvement.

Keywords: Fractional Order PI Controller, Integral Absolute Error (IAE), Genetic Algorithm, Z-N Method