Documents disponibles écrits par cet auteur

An intelligent power plant fault diagnostics for varying degree of severity and loading conditions / Liangyu Ma in IEEE transactions on energy conversion, Vol. 25 N° 2 (Juin 2010) 

Public ISBD [article]  in IEEE transactions on energy conversion > Vol. 25 N° 2 (Juin 2010) . - pp. 546 - 554 Titre : An intelligent power plant fault diagnostics for varying degree of severity and loading conditions Type de document : texte imprimé Auteurs : Liangyu Ma, Auteur ; Yongguang Ma, Auteur ; K. Y. Lee, Auteur Année de publication : 2010 Article en page(s) : pp. 546 - 554 Note générale : energy conversion Langues : Anglais (eng) Mots-clés : fault  diagnosis;  feedforward  neural  nets;  power  engineering  computing;  thermal  power  stations Résumé : Practical fault diagnosis of a thermal system is very important in ensuring safe and reliable operation of a power plant. However, it is a difficult task due to the structural complexity of a thermal system, varying degree of severity of a fault, and the wide range of operation of the power generating unit. An artificial neural network combined with optimal zoom search is proposed in this paper for recognizing varying degrees of faults in a power plant thermal system operating at different load level. The zoom search technology is based on the similarity rules of the feature variables to a same fault with different severity when the system topological structure does not change with fault or with different loading conditions. Two different types of symptoms, a trend symptom and a semantic symptom, are calculated and jointly used for on-line fault recognition, which results in a faster and more stable fault diagnosis. A feedforward neural network structure is adopted and an improved training method is introduced. A high-pressure feedwater heater system is taken as a target system for investigation. Several simulation tests for diagnosing a multidegree fault under different operating conditions are carried out on a 300-MW power plant simulator to demonstrate the validity of the method. En ligne : http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=5401094&sortType%3Das [...] [article] An intelligent power plant fault diagnostics for varying degree of severity and loading conditions [texte imprimé] / Liangyu Ma, Auteur ; Yongguang Ma, Auteur ; K. Y. Lee, Auteur . - 2010 . - pp. 546 - 554. energy conversion Langues : Anglais (eng) in IEEE transactions on energy conversion > Vol. 25 N° 2 (Juin 2010) . - pp. 546 - 554 Mots-clés : fault  diagnosis;  feedforward  neural  nets;  power  engineering  computing;  thermal  power  stations Résumé : Practical fault diagnosis of a thermal system is very important in ensuring safe and reliable operation of a power plant. However, it is a difficult task due to the structural complexity of a thermal system, varying degree of severity of a fault, and the wide range of operation of the power generating unit. An artificial neural network combined with optimal zoom search is proposed in this paper for recognizing varying degrees of faults in a power plant thermal system operating at different load level. The zoom search technology is based on the similarity rules of the feature variables to a same fault with different severity when the system topological structure does not change with fault or with different loading conditions. Two different types of symptoms, a trend symptom and a semantic symptom, are calculated and jointly used for on-line fault recognition, which results in a faster and more stable fault diagnosis. A feedforward neural network structure is adopted and an improved training method is introduced. A high-pressure feedwater heater system is taken as a target system for investigation. Several simulation tests for diagnosing a multidegree fault under different operating conditions are carried out on a 300-MW power plant simulator to demonstrate the validity of the method. En ligne : http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=5401094&sortType%3Das [...]

Controller design for a large-scale ultrasupercritical once-through boiler power plant / K. Y. Lee in IEEE transactions on energy conversion, Vol. 25, N° 4 (Décembre 2010) 

Public ISBD [article]  in IEEE transactions on energy conversion > Vol. 25, N° 4 (Décembre 2010) . - pp. 1063 - 1070 Titre : Controller design for a large-scale ultrasupercritical once-through boiler power plant Type de document : texte imprimé Auteurs : K. Y. Lee, Auteur ; Van Sickel, J.H., Auteur ; Hoffman, J. A., Auteur Année de publication : 2011 Article en page(s) : pp. 1063 - 1070 Note générale : energy conversion Langues : Anglais (eng) Mots-clés : Boilers;  neural  nets;  power  system  control;  power  system  simulation;  three-term  control Résumé : A large-scale once-through-type ultrasupercritical boiler power plant is investigated for the development of an analyzable model for use in developing an intelligent control system. Using data from the power plant, a model is realized using dynamically recurrent neural networks (NN). This requires the partitioning of multiple subsystems, which are each represented by an individual NN that when combined form the whole plant model. Modified predictive optimal control was used to drive the plant to desired states; however, due to the computational intensity of this approach, it could not be executed quickly enough to satisfy project requirements. As an alternative, a reference governor was implemented along with a PID feedback control system that utilizes intelligent gain tuning, which, while more complicated, satisfied the computational speed required for the controller to be realized. En ligne : http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=5594627&sortType%3Das [...] [article] Controller design for a large-scale ultrasupercritical once-through boiler power plant [texte imprimé] / K. Y. Lee, Auteur ; Van Sickel, J.H., Auteur ; Hoffman, J. A., Auteur . - 2011 . - pp. 1063 - 1070. energy conversion Langues : Anglais (eng) in IEEE transactions on energy conversion > Vol. 25, N° 4 (Décembre 2010) . - pp. 1063 - 1070 Mots-clés : Boilers;  neural  nets;  power  system  control;  power  system  simulation;  three-term  control Résumé : A large-scale once-through-type ultrasupercritical boiler power plant is investigated for the development of an analyzable model for use in developing an intelligent control system. Using data from the power plant, a model is realized using dynamically recurrent neural networks (NN). This requires the partitioning of multiple subsystems, which are each represented by an individual NN that when combined form the whole plant model. Modified predictive optimal control was used to drive the plant to desired states; however, due to the computational intensity of this approach, it could not be executed quickly enough to satisfy project requirements. As an alternative, a reference governor was implemented along with a PID feedback control system that utilizes intelligent gain tuning, which, while more complicated, satisfied the computational speed required for the controller to be realized. En ligne : http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=5594627&sortType%3Das [...]

Fuzzy fault diagnosis and accommodation system for hybrid fuel-cell/gas-turbine power plant / Yang Wenli in IEEE transactions on energy conversion, Vol. 25, N° 4 (Décembre 2010) 

Public ISBD [article]  in IEEE transactions on energy conversion > Vol. 25, N° 4 (Décembre 2010) . - pp. 1187 - 1194 Titre : Fuzzy fault diagnosis and accommodation system for hybrid fuel-cell/gas-turbine power plant Type de document : texte imprimé Auteurs : Yang Wenli, Auteur ; K. Y. Lee, Auteur ; Junker, S.T., Auteur Année de publication : 2011 Article en page(s) : pp. 1187 - 1194 Note générale : energy conversion Langues : Anglais (eng) Mots-clés : Fault  diagnosis;  fuel  cell  power  plants;fuzzy  control;  fuzzy  logic;  gas  turbine  power  stations;  hybrid  power  systems;  power  generation  control Résumé : The concept of hybrid fuel-cell power plants has shown its potential for applications and is already under commercialization. In a hybrid fuel-cell and turbine power plant, the control system is an essential component that guarantees reliable and efficient operations. However, due to the limited information possessed by particular local controllers, the plant may become degraded or unstable during system failures. To regulate the power plants under such abnormal situations, a fault diagnosis and accommodation (FDA) system based on fuzzy logic has been developed as an effective complement for the local control scheme. Being a quantitative approach, the fuzzy FDA system can be implemented with considerably lower complexities than an analytical fault regulator. The system structures and design methods are discussed in this paper. Three types of controllers are implemented and investigated. Simulation results are presented to verify the performance of the overall system. En ligne : http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=5575407&sortType%3Das [...] [article] Fuzzy fault diagnosis and accommodation system for hybrid fuel-cell/gas-turbine power plant [texte imprimé] / Yang Wenli, Auteur ; K. Y. Lee, Auteur ; Junker, S.T., Auteur . - 2011 . - pp. 1187 - 1194. energy conversion Langues : Anglais (eng) in IEEE transactions on energy conversion > Vol. 25, N° 4 (Décembre 2010) . - pp. 1187 - 1194 Mots-clés : Fault  diagnosis;  fuel  cell  power  plants;fuzzy  control;  fuzzy  logic;  gas  turbine  power  stations;  hybrid  power  systems;  power  generation  control Résumé : The concept of hybrid fuel-cell power plants has shown its potential for applications and is already under commercialization. In a hybrid fuel-cell and turbine power plant, the control system is an essential component that guarantees reliable and efficient operations. However, due to the limited information possessed by particular local controllers, the plant may become degraded or unstable during system failures. To regulate the power plants under such abnormal situations, a fault diagnosis and accommodation (FDA) system based on fuzzy logic has been developed as an effective complement for the local control scheme. Being a quantitative approach, the fuzzy FDA system can be implemented with considerably lower complexities than an analytical fault regulator. The system structures and design methods are discussed in this paper. Three types of controllers are implemented and investigated. Simulation results are presented to verify the performance of the overall system. En ligne : http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=5575407&sortType%3Das [...]

A multiagent-system-based intelligent reference governor for multiobjective optimal power plant operation / Heo, J.S. in IEEE transactions on energy conversion, Vol. 23 n°4 (Décembre 2008) 

Public ISBD [article]  in IEEE transactions on energy conversion > Vol. 23 n°4 (Décembre 2008) . - pp. 1082 - 1092 Titre : A multiagent-system-based intelligent reference governor for multiobjective optimal power plant operation Type de document : texte imprimé Auteurs : Heo, J.S., Auteur ; K. Y. Lee, Auteur Année de publication : 2009 Article en page(s) : pp. 1082 - 1092 Note générale : Energy conversion Langues : Anglais (eng) Mots-clés : Large-scale  systems;  multi-agent  systems;  nonlinear  functions;  particle  swarm  optimisation;  power  engineering  computing;  thermal  power  stations Résumé : A large-scale power plant requires optimal set points, namely references, in several control loops for multiobjective optimal operation. In a 600-MW oil-fired drum-type boiler power unit, the set points considered are for the main steam pressure and reheater/superheater steam temperatures. The set points should be mapped with the varying unit load demand and satisfy the conflicting requirements in power plant operation. In practice, the set points are obtained using fixed nonlinear functions in the unit master control in a plant, which are designed for the single objective of load tracking with heat balance. However, it does not allow for process optimization under the multitude of conflicting objectives, which may be newly introduced and different from the initial design objective. This paper presents a methodology, multiagent-system-based intelligent reference governor (MAS-IRG), to realize the optimal mapping by searching for the best solution to the multiobjective optimization problem that tackles conflicting requirements. In searching for the optimal set points, a heuristic optimization tool, particle swarm optimization, is utilized to solve the multiobjective optimization problem. The IRG is designed based on the proposed MAS to operate at a higher level of automation, to execute asynchronous computations, and to reduce the computational complexity. The approach provides the means to specify optimal set points for controllers under a diverse operating scenarios online. En ligne : http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=4675799&sortType%3Das [...] [article] A multiagent-system-based intelligent reference governor for multiobjective optimal power plant operation [texte imprimé] / Heo, J.S., Auteur ; K. Y. Lee, Auteur . - 2009 . - pp. 1082 - 1092. Energy conversion Langues : Anglais (eng) in IEEE transactions on energy conversion > Vol. 23 n°4 (Décembre 2008) . - pp. 1082 - 1092 Mots-clés : Large-scale  systems;  multi-agent  systems;  nonlinear  functions;  particle  swarm  optimisation;  power  engineering  computing;  thermal  power  stations Résumé : A large-scale power plant requires optimal set points, namely references, in several control loops for multiobjective optimal operation. In a 600-MW oil-fired drum-type boiler power unit, the set points considered are for the main steam pressure and reheater/superheater steam temperatures. The set points should be mapped with the varying unit load demand and satisfy the conflicting requirements in power plant operation. In practice, the set points are obtained using fixed nonlinear functions in the unit master control in a plant, which are designed for the single objective of load tracking with heat balance. However, it does not allow for process optimization under the multitude of conflicting objectives, which may be newly introduced and different from the initial design objective. This paper presents a methodology, multiagent-system-based intelligent reference governor (MAS-IRG), to realize the optimal mapping by searching for the best solution to the multiobjective optimization problem that tackles conflicting requirements. In searching for the optimal set points, a heuristic optimization tool, particle swarm optimization, is utilized to solve the multiobjective optimization problem. The IRG is designed based on the proposed MAS to operate at a higher level of automation, to execute asynchronous computations, and to reduce the computational complexity. The approach provides the means to specify optimal set points for controllers under a diverse operating scenarios online. En ligne : http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=4675799&sortType%3Das [...]

Simulation for fretting corrosion of tin-coated copper contacts / K. Y. Lee in Materials and corrosion, Vol. 62 N° 4 (Avril 2011) 

Public ISBD [article]  in Materials and corrosion > Vol. 62 N° 4 (Avril 2011) . - pp. 352–356 Titre : Simulation for fretting corrosion of tin-coated copper contacts Type de document : texte imprimé Auteurs : K. Y. Lee, Auteur ; D. K. Jeong, Auteur ; H. G. Joo, Auteur Année de publication : 2011 Article en page(s) : pp. 352–356 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Contact  resistance  Fretting  corrosion  Simulation  Surface  characterization Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The simulations of contact resistance variation under various oxide fractions are conducted. The copper oxide is assigned on the contact area with various fractions by the random distribution technique. The calculated contact resistance at each oxide area fraction is compared with the experimental result. The increase in contact resistance results in an increased oxide area fraction. DEWEY : 620.1 ISSN : 0847-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905533/abstract [article] Simulation for fretting corrosion of tin-coated copper contacts [texte imprimé] / K. Y. Lee, Auteur ; D. K. Jeong, Auteur ; H. G. Joo, Auteur . - 2011 . - pp. 352–356. Génie Mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 62 N° 4 (Avril 2011) . - pp. 352–356 Mots-clés : Contact  resistance  Fretting  corrosion  Simulation  Surface  characterization Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The simulations of contact resistance variation under various oxide fractions are conducted. The copper oxide is assigned on the contact area with various fractions by the random distribution technique. The calculated contact resistance at each oxide area fraction is compared with the experimental result. The increase in contact resistance results in an increased oxide area fraction. DEWEY : 620.1 ISSN : 0847-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905533/abstract