Relative gain array dynamic

Bristol s relative-gain array initiated an extensive and vigorous research effort in interaction and decoupling of control loops. There is a large number of papers with applications of Bristol s array, as well as several theoretical treatments. Today it has been shown that if dynamic interaction is important Bristol s method may lead to the wrong couplings. The following paper demonstrates this point ... 

Controllability indices, as Closed Loop Disturbance Gain (CLDG) and Performance Relative Gain Array (PRGA) predict in all situations better dynamic properties for the forward heat-integration scheme, compared with the reverse one. This behaviour is verified by closed loop simulation with the full non-linear model. 

Shows how to use quantitative analysis with steady-state and dynamic relative gain arrays (RGA and DRGA) to select control loop pairings reliably and to use the IMC model-based approach to provide preliminary tuning of single-loop PI controllers. 

The issue of this kind of control configuration has been investigated using frequency dependent formulations of measures such as the condition number, the Relative Gain Array by Bristol (1966) and the Relative Disturbance Gain by Stanley et al (1985). This paper will focus on discussing the dynamic control structure on the heat pump section and how each dynamic control structure affects on the stability of the integrated distillation column. 

Like other linear techniques, the relative-gain array assumes that the principle of superposition holds. In the published papers and books there is also an assumption, not implicit in the mathematics, that the steady-state gains give a true indication of interaction. For real systems dynamics effects may x just the opposite of steady-state effects and may be dominant. Further, since a distillation column is apt to be just one equipment piece in a sequence of process steps, there are usually fewer choices of control system structure than... 

---