When operators make controller adjustments, they do so based on many considerations, including the effect on multiple process variables and production goals, current constraints and alarms, experience and training, input from process engineers and operation supervision, and on production plans that typically derive from daily site-wide production planning and optimization (PP&O) meetings.

The entire operating team works together in this coordinated manner to meet production and optimization goals, while safeguarding reliable process operation.  This integral teamwork activity – essentially manual multivariable control – can be found in place on virtually every process operation in industry, because the multivariable nature of most processes demands it, and because it is the most natural and effective way to manage and operate complex industrial processes.

Automated multivariable control & optimization (aka APC) is the technology of automating this activity, i.e. closing multivariable loops for groups of related base-layer (BPC) controllers.  The benefits of APC are qualitatively the same as for closing BPC loops in the first place – more timeliness and consistency, fewer alarms and constraint violations, and greater process optimization.  Quantitatively, APC benefits may range from the intrinsic benefits of closing loops and improving the automation metrics (the same as single-loop management) to the large-scale ROIs typically associated with modern APC.