An analytical design method for PI/PID controller tuning is proposed for several types of processes with time delay. A single tuning formula gives enhanced disturbance rejection performance. The design method is based on the IMC approach, which has a single tuning parameter to adjust the performance and robustness of the controller. A simple tuning formula gives consistently better performance as compared to several well-known methods at the same
degree of robustness for stable and integrating process. The performance of the unstable process has been compared with other recently published methods which also show significant improvement in the proposed method. Furthermore, the robustness of the controller is investigated by inserting a perturbation uncertainty in all parameters simultaneously, again showing comparable results with other methods. An analysis has been performed for the uncertainty margin in the different process parameters for the robust controller design. It gives the guidelines of the Ms setting for the PI controller design based on the process parameters uncertainty. For the selection of the closed-loop time constant, (τc), a guideline is provided over a broad range of θ/τ ratios on the basis of the peak of maximum uncertainty (Ms). A comparison of the IAE has been conducted for the wide range of θ/τ ratio for the first order time delay process. The proposed method shows minimum IAE in compared to SIMC, while Lee et al. shows poor disturbance rejection in the lag dominant process. In the simulation study, the controllers were tuned to have the same degree of robustness by measuring the Ms, to obtain a reasonable comparison.
Desborough LD, Miller RM, Increasing customer value of industrial control performance monitoring.Honeywell’s experience, in Chemical Process Control .VI AIChE Symposium Series, Tuscon, Arizona, Jan. 2001, 2002., 2001
Grimholt C, Skogestad S, Optimal PI control and verification of the SIMC tuning rule, in Proceedings of the IFAC Conference on Advances in PID Control PID’12, Brescia (Italy) (2012)., 2012
Skogestad S, Grimholt C, The SIMC Method for Smooth PID Controller, in PID Control in the Third Millennium, Advances in Industrial Control, Springer, 147 (2012)., 2012
Alcantara S, Vilanova R, Pedret C, Skogestad S, A look into robustness/performance and servo/regulation issues in PI tuning, in Proceedings of the IFAC Conference on Advances in PID Control PID’12, Brescia, Italy (2012)., 2012
Lee J, Cho W, Edgar TF, Ind. Eng. Chem. Res., 52, 12973, 2013
Shamsuzzoha M, Ind. Eng. Chem. Res., 52, 12973, 2013
Alfaro VM, Vilanova R, Optimal robust tuning for 1DoF PI/PID control unifying FOPDT/SOPDT models, in IFAC Conference on Advances in PID Control PID’12, Brescia (Italy), March 28-30 (2012)., 2012