On the Computation of Disturbance Rejection Measures

In any process plant design, a central question is whether it is possible to achieve acceptable control with the available manipulated variables, while taking into account the disturbances that can be expected. Some little known controllability measures have been proposed to address such issues (Wolff, 1994; Skogestad and Wolff, 1992). The main reason these controllability measures have received little attention is probably that, while, their mathematical formulation was defined, no algorithms were provided to solve the mathematical problems. This paper shows how to calculate these controllability measures, and applies the algorithms to some process examples.