The topic of this seminar is modeling and control of the last part of the paper machine the drying section. Paper is dried by letting it pass through a series of steam heated cylinders and the evaporation is thus powered by the latent heat of vaporization of the steam. The moisture in the paper is controlled by adjusting the set point of the steam pressure controllers.
It is found that parts of the drying section can be modeled or approximated as an IPZ-model. This is a second order model containing an integrator, a pole, and a zero. Many different physical processes, especially with heat transfer can be modeled by IPZ-models. Both a black-box model and a physical model are given for the steam pressure process.

Tuning rules for both PI and PID control are derived based on optimization methods. Many of the results are verified by experiments on paper machines at different paper mills. The tuning rules has one tuning parameter and the experimental results are very promising. The research has been done in cooperation with Ola  Sloteke.