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Simulation and Control of a Nonlinear and Non-Minimum Phase Bioreactor

Baghbeheshti, Mostafa | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 45100 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Shahrokhi, Mohammad
  7. Abstract:
  8. Control of fermentation bioreactors with nonlinear behavior is a very important issue, especially when optimizing the biomass production is desired. The system in this situation works in two domains: minimum phase and non-minimum phase; and in transition from one domain into the other one the sign of process gain changes. For control of such a process in this work have been used two non-adaptive strategies and one adaptive strategy. The non-adaptive schemes are pole-placement and model predictive. The pole-placement technique as a linear control algorithm is used and its parameters are fixed by minimizing the objective function which has been used in predictive control technique. Another non-adaptive controller is generalized predictive control (GPC) that is typically used in industry. ARMA and Hammerstein models are used for process modeling. The applied adaptive controller is the AGPC. These algorithms are implemented to the fermentation bioreactor for controlling the biomass concentration with dilution rate as the manipulated variable and simulation results are compared. These results include set-point tracking, load rejection and model mismatch. The simulation results indicate that all control schemes have acceptable performance in minimum or non-minimum phase domain. The performance of AGPC controller in transition from one domain into the other one is investigated. At the end the performance of Hammerstein-based MPC controller for large set-point changes is evaluated
  9. Keywords:
  10. Bioreactor ; Nonminimum-Phase System ; Gain Sign Change ; Pole Placement Control ; Model Predictive Control

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