Simple tuning rules for feedforward compensators

Brief paper: Self-tuning regulator applied to a binary distillation column

Optimal feedforward compensators for systems with right-half plane zeros

A nonlinear feedback linearizing control (FLC) strategy is proposed within the differential geometric framework for temperature control of a refinery debutanizer column. The distillation model is verified by real data. The FLC control algorithm usually consists of a transformer, a state estimator and an external linear controller. Here, two state estimators, namely extended Kalman filter (EKF) and short-cut model-based open-loop estimator (SMBOLE), have been developed to device the hybrid FLC-EKF and FLC-SMBOLE control systems, respectively. In order to avoid estimator design complexity as well as computational burden, an ideal binary distillation model [light key (LK)/heavy key (HK)] has been used as an EKF predictor and open-loop estimator (OLE). In this article, a comparative study has been conducted between the FLC-EKF, FLC-SMBOLE and a classical dual-loop proportional integral derivative (PID) control structure. Simulation results show that despite the significant process/model mismatch, the proposed FLC controllers perform better than the PID control scheme.

A Hybrid FLC-EKF Scheme for Temperature Control of a Refinery Debutanizer Column

This study presents a control design methodology to address simultaneous robust feedforward and feedback tuning. A tuning guideline including tuning rules based on the time-domain response is introduced. Then, an optimisation algorithm is used in the frequency domain to find the optimal feedback–feedforward controller. Detailed simulations covering a wide range of industrial process models are carried out to demonstrate the validity of the proposed methodology and its advantages over other approaches.

A.Eli Nisenfeld

Papers

Applications of feedforward control to distillation columns