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Improvements in fault tolerance characteristics for large chemical plants: 1. waste water treatment plant with decentralized control / Zumoffen, David in Industrial & engineering chemistry research, Vol. 47 n°15 (Août 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°15 (Août 2008) . - p. 5664-5481 Titre : Improvements in fault tolerance characteristics for large chemical plants: 1. waste water treatment plant with decentralized control Type de document : texte imprimé Auteurs : Zumoffen, David, Auteur ; Basualdo, Marta, Auteur Année de publication : 2008 Article en page(s) : p. 5664-5481 Note générale : Bibliogr. p. 5481 Langues : Anglais (eng) Mots-clés : Waste  Water  Treatment  Plant;  FDIE  systems;  Fault-tolerant  scheme; Résumé : A decentralized control scheme integrated with a recently developed fault detection, isolation, and estimation (FDIE) system applied on a benchmark of wastewater treatment plant (WWTP) is discussed here. This work belongs to a series whose objective is to demonstrate quantitatively the achievable improvements on the fault-tolerance characteristics supported by the integration with FDIE systems. In the previous work, a decentralized structure applied on a larger benchmark (such as the pulp mill plant) was presented. Specific aspects that are related to that case study were successfully handled by this methodology. Here, the WWTP presents new scenarios based on the occurrence of faults and their incidence on the associated dynamic with this process. In this work, faults such as extra dead time at actuators and bias and slow drifts in sensors (which, in some cases, can cause saturation), are analyzed. Under these conditions, a real need exists for turning the existent control scheme into a fault-tolerant (FT) scheme. This is done through reconfiguration of the controllers, using online identification and model-based control (MBC) tools. As the main contribution of this paper, a rigorous quantitative analysis is performed that takes account of a complete set of simulation cases, showing different scenarios. The accurate comparison study is given through several indexes associated with the WWTP benchmark, and others that are useful for analyzing the methodology are proposed here. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800098t [article] Improvements in fault tolerance characteristics for large chemical plants: 1. waste water treatment plant with decentralized control [texte imprimé] / Zumoffen, David, Auteur ; Basualdo, Marta, Auteur . - 2008 . - p. 5664-5481. Bibliogr. p. 5481 Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°15 (Août 2008) . - p. 5664-5481 Mots-clés : Waste  Water  Treatment  Plant;  FDIE  systems;  Fault-tolerant  scheme; Résumé : A decentralized control scheme integrated with a recently developed fault detection, isolation, and estimation (FDIE) system applied on a benchmark of wastewater treatment plant (WWTP) is discussed here. This work belongs to a series whose objective is to demonstrate quantitatively the achievable improvements on the fault-tolerance characteristics supported by the integration with FDIE systems. In the previous work, a decentralized structure applied on a larger benchmark (such as the pulp mill plant) was presented. Specific aspects that are related to that case study were successfully handled by this methodology. Here, the WWTP presents new scenarios based on the occurrence of faults and their incidence on the associated dynamic with this process. In this work, faults such as extra dead time at actuators and bias and slow drifts in sensors (which, in some cases, can cause saturation), are analyzed. Under these conditions, a real need exists for turning the existent control scheme into a fault-tolerant (FT) scheme. This is done through reconfiguration of the controllers, using online identification and model-based control (MBC) tools. As the main contribution of this paper, a rigorous quantitative analysis is performed that takes account of a complete set of simulation cases, showing different scenarios. The accurate comparison study is given through several indexes associated with the WWTP benchmark, and others that are useful for analyzing the methodology are proposed here. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800098t

Improvements in fault tolerance characteristics for large chemical plants: 2. pulp mill process with model predictive control / Zumoffen, David in Industrial & engineering chemistry research, Vol. 47 n°15 (Août 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°15 (Août 2008) . - p. 5482–5500 Titre : Improvements in fault tolerance characteristics for large chemical plants: 2. pulp mill process with model predictive control Type de document : texte imprimé Auteurs : Zumoffen, David, Auteur ; Basualdo, Marta, Auteur ; Gonzalo Molina, Auteur Année de publication : 2008 Article en page(s) : p. 5482–5500 Note générale : Bibliogr. p. 5499-5500 Langues : Anglais (eng) Mots-clés : Large  chemical  plants;  Wastewater  treatment  plant;  FDIE  system;  Model  predictive  control Résumé : A model predictive control (MPC) scheme integrated with a recently developed fault detection, isolation, and estimation (FDIE) system applied on a pulp mill (PM) process is discussed. This work belongs to a series whose objective is to achieve improvements on the fault tolerance characteristics for conventional and advanced control schemes. In two previous works, different decentralized control structures were integrated with the same FDIE system. It was tested for large chemical plants, such as PM and wastewater treatment plant (WWTP) processes. Each one offered different dynamics and fault scenarios, because of the specific impact produced by the abnormal events considered. For doing rigorous comparisons, the PM process is the same as that studied in one of the previous works. Although the FDIE system presents the same general structure, it must be redesigned, because of the inherent fault-tolerant characteristics of the classical MPC. In this context, it is more difficult to determine the patterns associated with each fault. A complete set of simulation results, evaluated by the same indexes used in the previous work, together with a cost analysis about the process operational profits, is included. The comparisons are done with and without the FDIE system, alternative control solutions providing from the decentralized and MPC structures are evaluated. The case where the link with the FDIE system is done is indicated as fault-tolerant MPC (FTMPC). As new results, a rigorous quantitative analysis to answer the question about which is the real improvement that can be introduced by the FTMPC is made, accounting for very complex scenarios. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800100r [article] Improvements in fault tolerance characteristics for large chemical plants: 2. pulp mill process with model predictive control [texte imprimé] / Zumoffen, David, Auteur ; Basualdo, Marta, Auteur ; Gonzalo Molina, Auteur . - 2008 . - p. 5482–5500. Bibliogr. p. 5499-5500 Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°15 (Août 2008) . - p. 5482–5500 Mots-clés : Large  chemical  plants;  Wastewater  treatment  plant;  FDIE  system;  Model  predictive  control Résumé : A model predictive control (MPC) scheme integrated with a recently developed fault detection, isolation, and estimation (FDIE) system applied on a pulp mill (PM) process is discussed. This work belongs to a series whose objective is to achieve improvements on the fault tolerance characteristics for conventional and advanced control schemes. In two previous works, different decentralized control structures were integrated with the same FDIE system. It was tested for large chemical plants, such as PM and wastewater treatment plant (WWTP) processes. Each one offered different dynamics and fault scenarios, because of the specific impact produced by the abnormal events considered. For doing rigorous comparisons, the PM process is the same as that studied in one of the previous works. Although the FDIE system presents the same general structure, it must be redesigned, because of the inherent fault-tolerant characteristics of the classical MPC. In this context, it is more difficult to determine the patterns associated with each fault. A complete set of simulation results, evaluated by the same indexes used in the previous work, together with a cost analysis about the process operational profits, is included. The comparisons are done with and without the FDIE system, alternative control solutions providing from the decentralized and MPC structures are evaluated. The case where the link with the FDIE system is done is indicated as fault-tolerant MPC (FTMPC). As new results, a rigorous quantitative analysis to answer the question about which is the real improvement that can be introduced by the FTMPC is made, accounting for very complex scenarios. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800100r

A Systematic approach for the design of optimal monitoring systems for large scale processes / Zumoffen, David in Industrial & engineering chemistry research, Vol. 49 N° 4 (Fevrier 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 4 (Fevrier 2010) . - pp 1749–1761 Titre : A Systematic approach for the design of optimal monitoring systems for large scale processes Type de document : texte imprimé Auteurs : Zumoffen, David, Auteur ; Basualdo, Marta, Auteur Année de publication : 2010 Article en page(s) : pp 1749–1761 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Optimal  monitoring  systems  Large  scale  processes. Résumé : In this work a new concept for designing an efficient monitoring system for large scale chemical plants is presented. It is considered that the monitoring problem must be solved integrated with the optimal sensor location together with the plant-wide control structure design. The solution of these problems involves deciding among a great number of possible combinations between the input−output variables. It is done supported by the application of genetic algorithm (GA). The key new idea is to propose an adequate objective function, within the GA, that takes into account a fault detectability index based on combined statistics. Additionally, by using a specific penalty function, it is possible to drive the search to the less expensive structure, that is by using the lowest number of sensors. The well-known benchmark case of the Tennessee Eastman plant (TE) is chosen for testing this methodology and for discussion purposes. Since several authors have studied the TE case, the results obtained here can be rigorously compared with those already published. All of the previous works considered that every TE output variables were available for the abnormal events detection for designing the monitoring system. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9017836 [article] A Systematic approach for the design of optimal monitoring systems for large scale processes [texte imprimé] / Zumoffen, David, Auteur ; Basualdo, Marta, Auteur . - 2010 . - pp 1749–1761. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 4 (Fevrier 2010) . - pp 1749–1761 Mots-clés : Optimal  monitoring  systems  Large  scale  processes. Résumé : In this work a new concept for designing an efficient monitoring system for large scale chemical plants is presented. It is considered that the monitoring problem must be solved integrated with the optimal sensor location together with the plant-wide control structure design. The solution of these problems involves deciding among a great number of possible combinations between the input−output variables. It is done supported by the application of genetic algorithm (GA). The key new idea is to propose an adequate objective function, within the GA, that takes into account a fault detectability index based on combined statistics. Additionally, by using a specific penalty function, it is possible to drive the search to the less expensive structure, that is by using the lowest number of sensors. The well-known benchmark case of the Tennessee Eastman plant (TE) is chosen for testing this methodology and for discussion purposes. Since several authors have studied the TE case, the results obtained here can be rigorously compared with those already published. All of the previous works considered that every TE output variables were available for the abnormal events detection for designing the monitoring system. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9017836