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PEOPLE@HES-SO – Annuaire et Répertoire des compétences
PEOPLE@HES-SO – Annuaire et Répertoire des compétences

PEOPLE@HES-SO
Annuaire et Répertoire des compétences

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François Grégory

François Grégory

Professeur-e HES Associé-e

Compétences principales

Process Optimization

Real-Time Optimization

Automatic Control

Process monitoring and control

Systems Modelling

Energy Systems

Fuel Cells

  • Contact

  • Enseignement

  • Publications

  • Conférences

Contrat principal

Professeur-e HES Associé-e

Téléphone: +41 58 606 82 19

Bureau: ENP.23.N412

HES-SO Valais-Wallis - Haute Ecole d'Ingénierie
Rue de l'Industrie 23, 1950 Sion, CH
HEI - VS
Domaine
Technique et IT
Filière principale
Systèmes industriels
BSc HES-SO en Energie et techniques environnementales - HES-SO Valais-Wallis - Haute Ecole d'Ingénierie
  • mécatronique
  • automatique
  • Hydrogène et Piles à Combustible
BSc HES-SO en Ingénierie des sciences du vivant - HES-SO Valais-Wallis - Haute Ecole d'Ingénierie
  • Mesure-Commande-Régulation
MA BFH/HES-SO en Architecture - HES-SO Master
  • Modélisation et simulation
  • automatique
  • Optimisation
BSc HES-SO en Energie et techniques environnementales - HES-SO Valais-Wallis - Haute Ecole d'Ingénierie
  • Mesure-Commande-Régulation

2022

Real-time optimization of batch processes via optimizing feedback control
Chapitre de livre ArODES

Dominique Bonvin, Grégory François, Gianluca Rizzi, Michael Amrhein

Dans Asprion, Norbert, Bortz, Michael, Simulation and optimization in process engineering : the benefit of mathematical methods in applications of the chemical industry  (pp. 201-223). 2022,  Amsterdam : Elsevier

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Résumé:

A batch process is characterized by the repetition of time-varying operations of finite duration. Due to this repetition, there are two independent “time” variables, namely, the run time within a batch and the batch index. Accordingly, the optimization objective can be defined for a given batch or over several batches. This chapter formulates the dynamic optimization problem for a given batch and shows that it can be reformulated as a static optimization problem to be solved over several batches. Furthermore, it is shown how optimization can be seen as self-optimizing control that is implemented both within batch and in a batch-to-batch manner. The use of feedback control is of particular interest in the presence of uncertainty. This chapter describes how to set up the various control loops and implement optimizing feedback control. The approach is illustrated via the optimization of a batch distillation column.

2021

Robust modifier adaptation via worst-case and probabilistic approaches
Article scientifique ArODES

Jack Speakman, Grégory François

Industrial Engineering Chemistry Research,  2022, vol. 61, no. 1, pp. 515-529

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Résumé:

Worst-case and stochastic optimization schemes are used to safely operate chemical processes, with operating conditions that are guaranteed to be feasible in the presence of a plant-model mismatch, often at the expense of a less optimal operating point. Modifier adaptation (MA) is a methodology of real-time optimization (RTO) which uses measurements to iteratively modify the operating conditions until convergence, which is guaranteed to satisfy the Karush–Kuhn–Tucker conditions of the plant. However, MA is not guaranteed to remain feasible for every iteration, thus undermining the eventual more optimal operating conditions. This paper develops three multi-model RTO approaches using robust optimization techniques and a new filter which guarantees feasible iterates under a structural plant-model mismatch if the model uncertainty can upper-bound the second derivative of the plant. These approaches are compared to MA in the simulation of a chemical reactor, where all three converge to the plant optimum without violating the constraints.

A robust modifier adaptation method via Hessian augmentation using model uncertainties
Article scientifique ArODES

Jack Speakman, Aris Papasavvas, Grégory François

Journal of Process Control,  2021, vol. 99, pp. 28-40

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Résumé:

Typical model-based optimization approaches cannot handle plant-model mismatch, therefore the use of real-time optimization (RTO) schemes which take advantage of measurements from the plant is required. Modifier adaptation (MA) uses the measurements to add a bias to the model which iteratively matches the model with the local gradient estimates of the plant, leading to satisfaction of the Karush–Kuhn–Tucker (KKT) conditions of the plant upon convergence. Whilst feasibility of the convergence solution is guaranteed, there is no such promise of the feasibility of the iterates before convergence. Some methods have been proposed which can guarantee feasibility of the iterates, however all proposed methods suffer from being extremely conservative with long convergence times and are not readily applicable without global information of the plant. This article proposes an alternative approach which uses model uncertainties to avoid the use of unobtainable information whilst removing the overly conservative iterates of previous methods. This new approach is illustrated on the Williams-Otto CSTR, illustrating rapid convergence.

A robust modifier adaptation method via Hessian augmentation using model uncertainties
Article scientifique

Jack Speakman, Aris Papasavvas, François Grégory

Computers and Chemical Engineering, 2021 , vol.  99, pp.  28-40

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2020

Real-time optimization via modifier adaptation of closed-loop processes using transient measurements
Article scientifique

Jack Speakman, François Grégory

Computers and Chemical Engineering, 2020 , vol.  140

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Output modifier adaptation with filter-based constraints
Article scientifique

Aris Papasavvas, François Grégory

Journal of Process Control, 2020 , vol.  87, pp.  37-53

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2019

Real-Time Optimisation of Closed-Loop Processes Using Transient Measurements
Article scientifique

Jack Speakman, François Grégory

Computer Aided Chemical Engineering, 2019 , vol.  46, pp.  1249-1254

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Filter-based additional constraints to relax the model adequacy conditions in modifier adaptation
Article scientifique

Aris Papasavvas, François Grégory

IFAC-PapersOnLine, 2019 , vol.  52, no  1, pp.  58-63

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Filter-based Constraints to Easier Plant Feasibility in Modifier Adaptation Schemes
Article scientifique

Aris Papasavvas, François Grégory

Computer-Aided Chemical Engineering, 2019 , vol.  46, pp.  1267-1272

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Internal Modifier Adaptation for the Optimization of Large-Scale Plants with Inaccurate Models
Article scientifique

Aris Papasavvas, François Grégory

Industrial & Engineering Chemistry Research, 2019 , vol.  58, no  30

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2018

Real-Time Optimizing Control of an Experimental Crosswind Power Kite
Article scientifique

Sean Costello, François Grégory, Dominique Bonvin

IEEE Transactions on Control Systems Technology, 2018 , vol.  6, no  2, pp.  507-522

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2017

Use of Transient Measurements for Static Real-Time Optimization
Article scientifique

De Avila Ferreira Tafarel, François Grégory, Alejandro Marchetti, Dominique Bonvin

IFAC-PapersOnLine, 2017 , vol.  50, no  1, pp.  5737-5742

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Crosswind kite control – A benchmark problem for advanced control and dynamic optimization
Article scientifique

Sean Costello, François Grégory, Dominique Bonvin

European Journal of Control, 2017 , vol.  35, pp.  1-10

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Chapter 11- Control and Optimization of Batch Chemical Processes
Chapitre de livre

Dominique Bonvin, François Grégory

Dans Rohani Sohrab,  Coulson and Richardson's Chemical Engineering (Fourth Edition). 2017,  UK : Butterworth-Heinemann

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2016

Modifier adaptation for real-time optimization - Methods and applications
Article scientifique

Alejandro Marchetti, François Grégory, Timm Faulwasser, Dominique Bonvin

Processes, 2016 , vol.  4, no  4, pp.  55-90

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Extension of modifier adaptation for controlled plants using static open-loop models
Article scientifique

François Grégory, Sean Costello, Alejandro Marchetti, Dominique Bonvin

Computers and Chemical Engineering, 2016 , vol.  93, no  4, pp.  361-371

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A Directional Modifier-Adaptation Algorithm for Real-Time Optimization
Article scientifique

Sean Costello, François Grégory, Dominique Bonvin

Journal of Process Control, 2016 , vol.  39, pp.  64-76

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2015

On the use of transient information for static real-time optimization
Article scientifique

Alejandro Marchetti, François Grégory, Dominique Bonvin

Computing and Systems Technology Division 2015 - Core Programming Area at the 2015 AIChE Annual Meeting, 2015 , vol.  1, pp.  47-49

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Directional real-time optimization applied to a kite-control simulation benchmark
Article scientifique

Sean Costello, François Grégory, Dominique Bonvin

Proceedings of the European Control Conference, 2015

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Analysis of the maximum efficiency of kite-power systems
Article scientifique

Sean Costello, François Grégory, Dominique Bonvin

Journal of Renewable and Sustainable Energy, 2015 , vol.  7, no  5

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A therapy parameter-based model for predicting blood glucose concentrations in patients with type 1 diabetes
Article scientifique

Alain Bock, François Grégory, Denis Gillet

Computer Methods and Programs in Biomedicine, 2015 , vol.  118, no  2, pp.  107-123

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Application of Real-Time Optimization Methods to Energy Systems in the Presence of Uncertainties and Disturbances
Article scientifique

François Grégory

TMC Academic Journal, 2015 , vol.  9, no  2, pp.  19-40

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2014

Modifier adaptation for constrained closed-loop systems
Article scientifique

Sean Costello, François Grégory, Dominique Bonvin, Alejandro Marchetti

IFAC PapersOnline, 2014 , vol.  47, no  3

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Use of transient measurements for the optimization of steady-state performance via modifier adaptation
Article scientifique

François Grégory, Dominique Bonvin

Industrial & Engineering Chemistry Research, 2014 , vol.  53, no  13, pp.  5148-5159

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Equivalence between neighboring-extremal control and self-optimizing control for the steady-state optimization of dynamical systems
Article scientifique

François Grégory, Bala Srinivasan, Dominique Bonvin

Industrial & Engineering Chemistry Research, 2014 , vol.  53, no  18, pp.  7470-7478

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Implementation techniques for the SCFO experimental optimization framework
Article scientifique

Gene Bunin, François Grégory, Dominique Bonvin

ArXiV, 2014

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On linear and quadratic Lipschitz bounds for twice continuously differentiable functions
Article scientifique

Gene Bunin, François Grégory, Dominique Bonvin

ArXiV, 2014 , pp.  1-3

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Real-Time Optimization: Optimizing the Operation of Energy Systems in the Presence of Uncertainty and Disturbances
Article scientifique

François Grégory, Dominique Bonvin

Proceedings of the 13th SET Conference, 2014 , vol.  E40137

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Thèse d'Habilitation à Diriger les Recherches: Optimisation en Temps Réel: Optimiser les Performances des Procédés Chimiques malgré l’Incertitude et les Erreurs de Modélisation
Thèse de doctorat
Thèse d'Habilitation à Diriger les Recherches

François Grégory

2014,  Nancy : Université de Lorraine

2013

Use of convex model approximations for real-time optimization via modifier adaptation
Article scientifique

François Grégory, Dominique Bonvin

Industrial & Engineering Chemistry Research, 2013 , vol.  52, no  33

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The SCFO Real-Time Optimization Solver: Users' Guide (version 0.9.4)
Rapport

Gene Bunin, François Grégory, Dominique Bonvin

2013,  Lausanne : EPFL,  86  p.

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Résumé:

This is an open-source software for real-time optimisation of uncertain systems, that is, with imperfect models. 

Real-time optimization when plant and model have different sets of inputs
Article scientifique

Sean Costello, François Grégory, Dominique Bonvin

IFAC Proceedings Volumes, 2013 , vol.  46, no  32, pp.  39-44

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Real-time optimization for kites
Article scientifique

Sean Costello, François Grégory, Dominique Bonvin

IFAC Proceedings Volumes, 2013 , vol.  46, no  12, pp.  64-69

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Measurement-Based Real-Time Optimization of Chemical Processes
Article scientifique

François Grégory, Dominique Bonvin

Advances in Chemical Engineering, 2013 , vol.  43, pp.  1-50

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Iterative controller tuning by real-time optimization
Article scientifique

Gene Bunin, François Grégory, Dominique Bonvin

IFAC Proceedings Volumes, 2013 , vol.  46, no  32, pp.  21-26

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From discrete measurements to bounded gradient estimates: A look at some regularizing structures
Article scientifique

Gene Bunin, François Grégory, Dominique Bonvin

Industrial & Engineering Chemistry Research, 2013 , vol.  52, no  35

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A real-time optimization framework for the iterative controller tuning problem
Article scientifique

Gene Bunin, François Grégory, Dominique Bonvin

Processes, 2013 , vol.  1, no  2

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Sufficient Conditions for Feasibility and Optimality of Real-Time Optimization Schemes – I. Theoretical Foundations
Article scientifique

Gene Bunin, François Grégory, Dominique Bonvin

ArXiV, 2013

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Sufficient Conditions for Feasibility and Optimality of Real-Time Optimization Schemes – II. Implementation Issues
Article scientifique

Gene Bunin, François Grégory, Dominique Bonvin

ArXiV, 2013

Lien vers la publication

Use of Transient Measurements for Real-Time Optimization via Modifier Adaptation
Article scientifique

François Grégory

Récents Progrès en Génie des Procédés, 2013 , vol.  104

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2012

Run-to-Run MPC Tuning via Gradient Descent
Article scientifique

Gene Bunin, Fernando Fraire Tirado, François Grégory, Dominique Bonvin

Computer-Aided Chemical Engineering, 2012 , vol.  30, pp.  927-931

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Exploiting local quasiconvexity for gradient estimation in modifier-adaptation schemes
Article scientifique

François Grégory

Proceedings of 2012 American Control Conference (ACC), 2012 , pp.  2806-2811

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Experimental real-time optimization of a solid oxide fuel cell stack via constraint adaptation
Article scientifique

Gene Bunin, Zacharie Wuillemin, François Grégory, Arata Nakajo, Leonidas Tsikonis, Dominique Bonvin

Energy, 2012 , vol.  39, no  1, pp.  54-62

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Comparison of six implicit real-time optimization schemes
Article scientifique

François Grégory, Bala Srinivasan, Dominique Bonvin

Journal Européen des Systèmes Automatisés, 2012 , vol.  46, no  2-3, pp.  291-305

2011

Control of Polymerization Processes
Chapitre de livre

François Grégory

Dans William Levine,  The Control Handbook, 2nd Edition. 2011,  London, UK : CRC Press

Preclinically assessed optimal control of postprandial glucose excursions for type 1 patients with diabetes
Article scientifique

Thierry Prud'homme, Alain Bock, François Grégory, Denis Gillet

Proceedings of the 2011 IEEE International Conference on Automation Science and Engineering, 2011 , pp.  702-707

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Optimal Service Pricing for a Cloud Cache
Article scientifique

Verena Kantere, Debabrata Dash, François Grégory, Sofia Kyriakopoulou, Anastasia Ailamaki

IEEE Transactions on Knowledge and Data Engineering, 2011 , vol.  23, no  9, pp.  1345-1358

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Modifier Adaptation for Run-to-Run Optimization of Transient Processes
Article scientifique

Sean Costello, François Grégory, Bala Srinivasan, Dominique Bonvin

IFAC Proceedings Volumes, 2011 , vol.  44, no  1

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Input filter design for feasibility in constraint-adaptation schemes
Article scientifique

Gene Bunin, François Grégory, Bala Srinivasan, Dominique Bonvin

IFAC Proceedings Volumes, 2011 , vol.  44, no  1, pp.  5585-5590

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Comparison of Gradient Estimation Methods for Real-time Optimization
Article scientifique

Bala Srinivasan, François Grégory, Dominique Bonvin

Computer Aided Chemical Engineering, 2011 , vol.  29, pp.  607-611

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A Minimal Exercise Extension for Models of the Glucoregulatory System
Article scientifique

Alain Bock, François Grégory, Thierry Prud'homme, Denis Gillet

Computer Aided Chemical Engineering, 2011 , vol.  29, pp.  1520-1524

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A globally convergent algorithm for the run-to-run control of systems with sector nonlinearities
Article scientifique

François Grégory, Bala Srinivasan, Dominique Bonvin

Industrial & Engineering Chemistry Research, 2011 , vol.  50, no  3, pp.  1410-1418

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2010

Two-Layered Real-Time Optimization of a Solid Oxide Fuel Cell Stack
Article scientifique

Gene Bunin, François Grégory, Dominique Bonvin

IFAC Proceedings Volumes, 2010 , vol.  43, no  5, pp.  847-852

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Experimental real-time optimization of a solid oxide fuel cell stack via constraint adaptation
Article scientifique

François Grégory, Gene Bunin, Zacharie Wuillemin, Arata Nakajo, Leonidas Tsikonis, Dominique Bonvin

Proceedings of the 23rd International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems (ECOS), 2010 , vol.  V, pp.  141-148

2008

A prototype for on-line monitoring and control of energy performance for renewable energy buildings
Article scientifique

Benjamin Paris, Julien Eynard, François Grégory, Thierry Talbert, Monique Polit

Proceedings of the Fifth International Conference on Informatics in Control, Automation and Robotics, 2008 , vol.  4, no  ICINCO, pp.  125-130

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Gestion des ressources énergétiques d’un bâtiment: contrôle flou
Article scientifique

Benjamin Paris, Julien Eynard, François Grégory, Thierry Talbert, Frédéric Thiéry

Proceedings of IBPSA France 2008, 2008

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2005

Use of measurements for enforcing the necessary conditions of optimality in the presence of constraints and uncertainty
Article scientifique

François Grégory, Bala Srinivasan, Dominique Bonvin

Journal of Process Control, 2005 , vol.  15, no  6, pp.  701-712

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A globally convergent run-to-run control algorithm with improved rate of convergence
Article scientifique

François Grégory, Bala Srinivasan, Dominique Bonvin

Proceedings of the 2005, American Control Conference, 2005, 2005 , vol.  3, pp.  1901-1906

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2004

Trajectory Following for the Optimization of a Batch Polymerization Reactor
Article scientifique

Carsten Welz, François Grégory, Bala Srinivasan

Proceedings of the BatchPro Symposium, 2004

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Run-to-run adaptation of a semiadiabatic policy for the optimization of an industrial batch polymerization process
Article scientifique

François Grégory, Bala Srinivasan, Dominique Bonvin, Jose Hernandes Barajas, David Hunkeler

Industrial & Engineering Chemistry Research, 2004 , vol.  43, no  23, pp.  7238-7242

Thèse de Doctorat: Measurement-based run-to-run optimization of batch processes: application to industrial acrylamide copolymerization
Thèse de doctorat

François Grégory

2004,  Lausanne : EPFL.  162  p.

Bonvin Dominique, Srinivasan Bala

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Dynamic optimization of batch emulsion polymerization using MSIMPSA, a simulated-annealing-based algorithm
Article scientifique

Ricardo Lima, François Grégory, Bala Srinivasan, Romualdo Salcedo

Industrial & Engineering Chemistry Research, 2004 , vol.  43, no  24, pp.  7796-7806

2003

Convergence analysis of run-to-run control for a class of nonlinear systems
Article scientifique

François Grégory, Bala Srinivasan, Dominique Bonvin

Proceedings of the 2003 American Control Conference, 2003 , vol.  4, pp.  3032-3037

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2002

Run-to-run optimization of batch emulsion polymerization
Article scientifique

François Grégory, Bala Srinivasan, Dominique Bonvin

IFAC Proceedings Volumes, 2002 , vol.  35, no  1, pp.  363-368

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2024

Modeling and real-time optimization of a µ-CHP SOFC system
Conférence ArODES

Hangyu Yu, Tafarel de Avila Ferreira, Grégory François

Proceedings of the 16th European SOFC & SOE Forum (EFCF 2024), 2-5 July 2024, Lucerne, Switzerland

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Résumé:

Solid oxide fuel cell (SOFC) technology is of great potential for efficient combined heat and power (CHP) generation with low overall emissions. To ensure safe and efficient operations of μ-CHP SOFC systems, appropriate control and optimization methods are required. This is generally achieved by using model-based optimization techniques, whereby operating conditions that maximize efficiency and ensure constraint satisfaction are sought. However, mismatch or disturbances always exist between a ‘plant’ (actual system) and its model, and standard model-based techniques are thus not sufficient. To circumvent this, a constraint-adaptation (CA)-based real-time optimization (RTO) algorithm has been proposed to drive the system to optimal efficiency, while enforcing constraint satisfaction, despite plant-model mismatch and disturbances. The μ-CHP SOFC system, depicted in Figure 1, comprises six components: a catalytic partial oxidation reactor, a SOFC cell stack, an afterburner, a startup burner, an air heat exchanger, and a water heat exchanger. RTO does not require a high-accuracy model since it mostly relies on updating the model optimality conditions through the available measurements. In this context, a lumped model that captures the main features of the μ- CHP SOFC system is developed and tuned to match experimental data. The performance of CA-based RTO was systematically evaluated. Various scenarios aiming at optimizing either electrical or CHP efficiencies for different load profiles, were tested to verify the robustness of the proposed methodology. CA-RTO not only demonstrated its capability to optimize the SOFC system efficiently but also maintained the system within a safe operating window even despite disturbances and plant-model mismatch.

2018

Modifier Adaptation Adaptation for Real-Time Optimization – Basic Idea and Recent Developments
Conférence

Alejandro Marchetti, François Grégory, Timm Faulwasser, Dominique Bonvin

7th International Conference on High Performance Scientific Computing. Modeling, Simulation and Optimization of Complex Processes, 19.03.2018 - 23.04.2018, Hanoi, Vietnam

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2017

Overview of the recent developments in Real-Time Optimisation via Modifier Adaptation
Conférence

François Grégory

16eme congres de la Société Francaise de Genie des Procédés, 11.07.2017 - 13.07.2017, Nancy, France

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Optimal service pricing for a cloud cache
Conférence

Verena Kantere, Debabrata Dash, François Grégory, Sofia Kyriakopoulou, Anastasia Ailamaki

10th Hellenic Data Management Symposium, 17.06.2017 - 17.06.2017, Athens, Greece

2013

Real-Time Optimization of Chemical Processes
Conférence
Plenary Talk

Dominique Bonvin, François Grégory, Gene Bunin

14eme Congres de la SFGP, 08.10.2013 - 10.10.2013, Lyon, France

2010

Model Predictive Control of an Experimental Solid Oxide Fuel Cell Stack
Conférence

François Grégory

7th Symposium on Fuel Cell Modeling and Experimental Validation, 16.04.2010 - 16.04.2021, Morges, Switzerland

Lien vers la conférence

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