APMonitor

Local Options | Global Options

 Type: Integer, Input
 Default Value: 1
 Description: Tiered order of Manipulated Variables (MVs)
              and Controlled Variables (CVs)

TIER is an ascending order of precedence for optimization. Tuning an application with multiple objectives can be challenging to coordinate the weights of competing objectives although there is a clear rank priority order. TIER gives the option to split the degrees of freedom into multiple sub-optimization problems. The highest priority values are optimized first while the subsequent priority values are optimized as a next step. Valid TIER values for MVs and CVs are between 1 and 100. There are up to 100 optimization levels and individual MVs / CVs must be at the same TIER value to be included in the sub-optimization problem. The STATUS must also be ON (1) for an MV to be a degree of freedom. The STATUS must also be ON (1) for an CV to be included in the objective function. If there is a sub-optimization problem that has no MV degrees of freedom, a warning message is displayed. Consider the situation with 2 MVs and 2 CVs with TIER 1 and 2 for each type (MV₁,MV₂,CV₁,CV₂). The solver would first optimize the set MV₁ and CV₁. It would then turn off the MV₁ status and fix it at the optimized values and remove the CV₁ objective function contribution. It would then optimize the set MV₂ and CV₂. The optimization occurs in two separate steps but the final reported solution includes the new MV₁ and MV₂ optimized profiles.

See also Multi-Objective Optimization