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Networked control of distributed energy resources / Yulei Sun in Industrial & engineering chemistry research, Vol. 48 N° 21 (Novembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 21 (Novembre 2009) . - pp. 9590–9602 Titre : Networked control of distributed energy resources : application to solid oxide fuel cells Type de document : texte imprimé Auteurs : Yulei Sun, Auteur ; Sathyendra Ghantasala, Auteur ; Nael H. El-Farra, Auteur Année de publication : 2010 Article en page(s) : pp. 9590–9602 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Distributed  energy  resources  Ssolid  oxide  fuel  cell Résumé : This paper presents a model-based networked control approach for managing distributed energy resources (DERs) over communication networks. As a model system, we consider a solid oxide fuel cell (SOFC) plant that communicates with the central controller over a bandwidth-constrained communication network that is shared by several other DERs. The objective is to regulate the power output of the fuel cell while keeping the communication requirements with the controller to a minimum in order to reduce unnecessary network utilization and minimize the susceptibility of the SOFC plant to possible communication disruptions in the network. Initially, a feedback control law is designed to regulate the power output of the SOFC plant at a desired set-point by manipulating the inlet fuel flow rate. Network utilization is then reduced by minimizing the rate of transfer of information between the fuel cell sensors and the central controller without sacrificing the desired stability or performance properties. To this end, a dynamic model of the SOFC plant is embedded in the controller to approximate the dynamics of the plant when measurements are not transmitted by the sensors, and the state of the model is updated using the actual state that is provided by the SOFC plant sensors at discrete time instances. When full-state measurements are not available, an appropriate state observer is included in the control structure to generate state estimates from the measured outputs, which are then used to update the model states. An explicit characterization of the maximum allowable transfer time between the sensor suite of the SOFC plant and the controller (i.e., the minimum allowable communication rate) is obtained under both state and output feedback control in terms of plant-model mismatch and the choice of control law. The characterization accounts for both stability and performance considerations. Finally, numerical simulations that demonstrate the implementation of the networked control architecture and its disturbance handling capabilities are presented. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9008869 [article] Networked control of distributed energy resources : application to solid oxide fuel cells [texte imprimé] / Yulei Sun, Auteur ; Sathyendra Ghantasala, Auteur ; Nael H. El-Farra, Auteur . - 2010 . - pp. 9590–9602. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 21 (Novembre 2009) . - pp. 9590–9602 Mots-clés : Distributed  energy  resources  Ssolid  oxide  fuel  cell Résumé : This paper presents a model-based networked control approach for managing distributed energy resources (DERs) over communication networks. As a model system, we consider a solid oxide fuel cell (SOFC) plant that communicates with the central controller over a bandwidth-constrained communication network that is shared by several other DERs. The objective is to regulate the power output of the fuel cell while keeping the communication requirements with the controller to a minimum in order to reduce unnecessary network utilization and minimize the susceptibility of the SOFC plant to possible communication disruptions in the network. Initially, a feedback control law is designed to regulate the power output of the SOFC plant at a desired set-point by manipulating the inlet fuel flow rate. Network utilization is then reduced by minimizing the rate of transfer of information between the fuel cell sensors and the central controller without sacrificing the desired stability or performance properties. To this end, a dynamic model of the SOFC plant is embedded in the controller to approximate the dynamics of the plant when measurements are not transmitted by the sensors, and the state of the model is updated using the actual state that is provided by the SOFC plant sensors at discrete time instances. When full-state measurements are not available, an appropriate state observer is included in the control structure to generate state estimates from the measured outputs, which are then used to update the model states. An explicit characterization of the maximum allowable transfer time between the sensor suite of the SOFC plant and the controller (i.e., the minimum allowable communication rate) is obtained under both state and output feedback control in terms of plant-model mismatch and the choice of control law. The characterization accounts for both stability and performance considerations. Finally, numerical simulations that demonstrate the implementation of the networked control architecture and its disturbance handling capabilities are presented. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9008869

A quasi-decentralized approach for networked state estimation and control of process systems / Yulei Sun in Industrial & engineering chemistry research, Vol. 49 N° 17 (Septembre 1, 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 17 (Septembre 1, 2010) . - pp 7957–7971 Titre : A quasi-decentralized approach for networked state estimation and control of process systems Type de document : texte imprimé Auteurs : Yulei Sun, Auteur ; Nael H. El-Farra, Auteur Année de publication : 2010 Article en page(s) : pp 7957–7971 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Control  process  systems. Résumé : A quasi-decentralized state estimation and control architecture for plants with limited state measurements and distributed, interconnected units that exchange information over a shared communication network is developed in this work. The objective is to stabilize the plant while minimizing unnecessary network resource utilization and communication costs. The networked control architecture is composed of a family of local control systems that transmit their data in a discrete (on/off) fashion over the network. Each control system includes a state observer that generates estimates of the local state variables from the measured outputs. The estimates are used to implement the local feedback control law and are also shared over the network with the control systems of the interconnected units to account for the interactions between the units. To reduce the exchange of information over the network as much as possible without sacrificing stability, dynamic models of the interconnected units are embedded in the local control system of each unit to provide it with an estimate of the evolution of its neighbors when data are not transmitted through the network. The state of each model is then updated using the state estimate generated by the observer of the corresponding unit and transmitted over the network when communication is re-established. An explicit characterization of the maximum allowable update period (i.e., minimum cross communication frequency between the distributed control systems) needed to enforce the desired stability and performance properties is obtained in terms of the plant−model mismatch, controller, and observer design parameters. The design and implementation of the developed architecture are illustrated using a chemical plant example and compared with other possible networked control strategies. The comparison reveals that the lack of full state measurements imposes limitations on the maximum allowable update period, even if the models used to recreate the plant units’ dynamics are accurate. It is also shown that the quasi-decentralized control architecture is more robust than a centralized networked control structure, with respect to communication suspension. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1000746 [article] A quasi-decentralized approach for networked state estimation and control of process systems [texte imprimé] / Yulei Sun, Auteur ; Nael H. El-Farra, Auteur . - 2010 . - pp 7957–7971. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 17 (Septembre 1, 2010) . - pp 7957–7971 Mots-clés : Control  process  systems. Résumé : A quasi-decentralized state estimation and control architecture for plants with limited state measurements and distributed, interconnected units that exchange information over a shared communication network is developed in this work. The objective is to stabilize the plant while minimizing unnecessary network resource utilization and communication costs. The networked control architecture is composed of a family of local control systems that transmit their data in a discrete (on/off) fashion over the network. Each control system includes a state observer that generates estimates of the local state variables from the measured outputs. The estimates are used to implement the local feedback control law and are also shared over the network with the control systems of the interconnected units to account for the interactions between the units. To reduce the exchange of information over the network as much as possible without sacrificing stability, dynamic models of the interconnected units are embedded in the local control system of each unit to provide it with an estimate of the evolution of its neighbors when data are not transmitted through the network. The state of each model is then updated using the state estimate generated by the observer of the corresponding unit and transmitted over the network when communication is re-established. An explicit characterization of the maximum allowable update period (i.e., minimum cross communication frequency between the distributed control systems) needed to enforce the desired stability and performance properties is obtained in terms of the plant−model mismatch, controller, and observer design parameters. The design and implementation of the developed architecture are illustrated using a chemical plant example and compared with other possible networked control strategies. The comparison reveals that the lack of full state measurements imposes limitations on the maximum allowable update period, even if the models used to recreate the plant units’ dynamics are accurate. It is also shown that the quasi-decentralized control architecture is more robust than a centralized networked control structure, with respect to communication suspension. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1000746