On the dynamics and control of a class of continuous digesters. (October 2015)

• Record Type: Journal Article
• Authors: Schaum, Alexander; Alvarez, Jesus; Garcia-Sandoval, Juan P.; Gonzalez-Alvarez, Victor M.
• Is Part Of: Journal of process control. Volume 34(2015:Oct.)
• Page Start: 82
• Page End: 96
• Publication Date: 2015-10
• Subjects: Continuous anaerobic digestion -- Stoichiometric invariants -- Control input constraints -- PI control -- Robust nonlocal stability; Process control -- Periodicals; Fabrication -- Contrôle -- Périodiques; Process control; Periodicals; Electronic journals; 660.281
• DOI: 10.1016/j.jprocont.2015.07.004
• Languages: English
• ISSNs: 0959-1524

Abstract

Abstract : Highlights: The saturated OF control problem for a class of four-state anaerobic digesters with volatile fatty acids (VFA) measurement is addressed. The reactor must operate about a maximum VFA consumption steadystate that is locally stable and can be structurally unstable. The problem is addressed as an interlaced control-observer design in the light of passivity, observability, and bifurcation properties. A nonlocally robustly stabilizing saturated linear PI controller with antiwindup protection and tuning guidelines is obtained. Closed-loop robust stability conditions and comparison against optimality-based switching control are provided. Abstract: The saturated OF control problem for a class of four-state anaerobic digesters with volatile fatty acids (VFAs) measurement is addressed. The reactor must operate about an optimal steady-state, with maximum VFA consumption that is locally open-loop stable but not necessarily structurally stable. The problem is addressed as an interlaced control-observer design in the light of passivity, observability, and bifurcation properties. The result is a saturated linear PI controller with: (i) systematic construction and tuning and (ii) nonlocal robust stability conditions in terms of control gains and limits. The proposed approach is illustrated with a representative case example through numerical simulations, including a comparison with the switching control approach.