Two-Degree-of-Freedom Control Scheme for Processes With Large Time Delay

In this paper, an analytical two-degree-of-freedom-control scheme is proposed for controlling processes with large time delay. The main contributions of this paper are that a setpoint response controller and an H∞ PID load-loop controller are developed based on optimal control theory, and control parameters are derived analytically. This structure can also be used to control integrating or unstable processes.