Multivariable PI Control of Industrial Paper Machine Headboxes

Production rates in modern paper machines are increasing all the time. This poses challenging requirements for control of different subprocesses in the paper machine, e.g. for the headbox. Currently, scalar controllers are used for headbox control in industrial practice almost everywhere. Headbox control has been a favorite example of multivariable control in many simulation and laboratory studies but not in industry. This paper presents an application of multivariable PI controller to the paper machine headbox. The procedure takes into account the limited tests that can be performed in practice, simplicity in structure and tuning, and realization using modern distributed automation systems.