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SUMMARY:Control of a System with Time Delay – Chlorination of  Wastewate
 r.
DTSTART:20100924T101500
DTSTAMP:20260510T053627Z
UID:32d9764561b5f028c025eb5bc8750cf84dc4bad3fa1584afc56311db
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. O. Crisalle\, Department of Chemical Engineering Univers
 ity of Florida\, Gainesville\, U.S.A.\nDynamic systems that exhibit a larg
 e variations in dead-time (also known as transport delay) effect are parti
 cularly challenging to control in a fashion that ensures both closed-loop 
 stability and adequate performance.  We review results characterizing the 
 robustness of the Smith Predictor control scheme\, a technique widely used
  in chemical engineering applications to address the challenges posed by t
 ime-delay systems.  Practical experience and a vast literature record sugg
 est that this control method may not be particularly robust.  In fact\, un
 der certain conditions the control loop may become unstable when the estim
 ated delay is affected by very small errors\, a perplexing behavior.  A co
 mplete framework is presented to assess in a quantitative fashion the robu
 stness of Smith Predictor designs.  \nTypical municipal wastewater chlorin
 ation systems are affected by large time-varying delays.  Chlorine is adde
 d as a disinfectant in a fashion that ensures adequate retention time in t
 he basin\, while satisfying regulations on its concentration at the discha
 rge point.  This talk shows that typical control schemes are unable to eff
 ectively reject the adverse effect of inlet flow rate variations that lead
  to significant time-delay fluctuations.  Instead of implementing a Smith 
 Predictor scheme\, which may lack robustness under these circumstances\, a
 n automatic control solution that involves engineering redesign of the pla
 nt is proposed and evaluated.  A new residence-time controller is advocate
 d as a solution that involves both feedback and feedforward architectures 
 and that can be deployed using standard PID software.
LOCATION:ME C2 405
STATUS:CONFIRMED
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