Application of enhanced LQG/LTR for distillation control

O´Dell and Misawa (1995) proposed a modification to the traditional LQG/LTR design procedure which provides uniform singular values across all frequencies for the target loop. The modification is easy to implement and significantly improves the performance of the LQG/LTR compensator. This article explores applicability of the technique for distillation column control, the most common multivariable control problem in the process industries. When applied to the Wood/Berry column (1973), performance of the enhanced LQG/LTR compensator is found to be comparable to a MAC model predictive controller and significantly better than traditional SISO PI control. Despite the lack of guaranteed performance and robust stability for nonlinear, nonminimum phase plants, the results suggest further consideration of enhanced LQG/LTR for application in the process industries