Using the Relative Disturbance Gain to Analyse Process Operability

The Relative Disturbance Gain (RDG) is a recently introduced technique for analysing process operability. The RDG can be used to estimate closed loop performance of multivariable control schemes from open loop, steady state process gains. In this paper new results on the relationship of the RDG to the closed loop transfer function are presented. In addition, the importance of the type of disturbance on interaction and control performance is demonstrated. Lastly the use of the RDG to configure decouplers is illustrated. The RDG estimates are validated with simulations of a reactor model and a distillation tower model.