Real-Time Control of Pressure Plant Using 2DOF Fractional-Order PID Controller

Control of real-time pressure process is quite challenging due to high nonlinearity and sensitivity. PID controllers being the most employed for industrial applications have the potential for control of such processes. This is due to the PID's advantages of simple structure, ease of tuning and implementation. However, its performance degrades during set-point change and high external disturbances due to high sensitivity and nonlinearity of the pressure plant. Therefore, this paper proposes the two-degree-of-freedom fractional-order PID (2DOF-FOPID) controller for real-time control of pressure process in both parallel and series configurations. Furthermore, the controller parameters are obtained experimentally using Ziegler-Nichols and closed-loop set-point approaches. The controller has the advantages of improving set-point tracking and disturbance rejection performance through smoother control action over the conventional PID. From the real-time experimental results obtained, the proposed approach outperforms PID, fractional-order PID and 2DOF-PID controllers in terms of overshoot and settling time. Hence, the approach has better set-point tracking ability and disturbance rejection capability. Furthermore, the control action of the approach is less affected by undesired oscillations and derivative kick effect thereby extending the life of actuator.