Parameter Scheduling and Adaptive Control of Nonlinear Processes -
Processes with streams comprised of gases, liquids, powders, slurries and melts tend to exhibit changing (or nonlinear) process behavior as operating level changes. As we explore in this article, processes that are nonlinear with operating level will experience a degrading controller performance whenever the measured process variable (PV) moves away from the design level of operation. We demonstrate this problem on the heat exchanger under PI control. If we decide that a change in performance with operating level is not acceptable for our application, then parameter scheduled adaptive control may be the appropriate solution. Developing an adaptive control strategy requires additional effort and expense. Before we start such a project, we should be sure that the loop has sufficient impact on our profitability to justify the investment.
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