Dual Composition Control of a Distillation Column Using Proportional-Integral-Plus (PIP) Control

The paper presents a control formulation termed proportional-integral-plus. This controller is considered as an extension to PI and PID control, but with additional feedback and input compensators. Using special kind of the nonminimum state space model with integral-of-error state makes the controller simpler in using regulator optimal control to find state variable feedback for both set-point tracking and regulation control scheme. Furthermore, it is a multi-input multi-output control system and there is no restriction on the number of controlled variables. Using past values of inputs and outputs as states, there is no need for state observer as it is common in optimal control and therefore input output data can be used in parameter estimation as linear time invariant or time variable parameter models. The structure of this controller is something like a PI controller with excess gains to compensate the effects of high order transfer function of the system. Control of a simulated “depropanizer” demonstrates the performance of this controller.

Keywords:

PIP control , NMSS , SVF , distillation column