The Experts below are selected from a list of 231 Experts worldwide ranked by ideXlab platform
Duarte M. Sousa - One of the best experts on this subject based on the ideXlab platform.
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Understanding the doubly fed induction generator during voltage dips
IEEE Transactions on Energy Conversion, 2012Co-Authors: G. D. Marques, Duarte M. SousaAbstract:The doubly fed induction generator (DFIG) is normally controlled with stator-flux orientation. The DFIG is a poorly Damped System with a natural frequency near the grid frequency. This leads to natural oscillations on the stator flux and on other variables. When voltage dips occur, there are oscillations on the stator flux that produces electromotive forces and consequently disturbances on the rotor currents. This paper presents a comprehensive study of the DFIG during voltage dips. The method presented in this paper, valid for symmetric and for asymmetric voltage dips, is based on the classical model of the induction machine with stator flux orientation and neglects only a small part of the cross-coupling terms. The response depends on the design methodology of the proportional-integral inner controllers. Analytical, simulation, and experimental results are shown. The analysis and results can be divided into two sets depending if the voltage dip magnitude is smaller or deeper than 0.5 p.u. © 2012 IEEE.
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EUROCON - Analysis of the DFIG during voltage dips
2011 IEEE EUROCON - International Conference on Computer as a Tool, 2011Co-Authors: G. D. Marques, Duarte M. SousaAbstract:The doubly-fed induction generator (DFIG) is normally controlled with stator-flux orientation. Stator-voltage orientation and other methods like Direct Power Control can also be adopted. It is a poorly Damped System with a natural frequency near the grid frequency. This leads to natural oscillations on the flux and torque and, for stator-flux orientation, in some cases, to instability. When voltage dips occur, the stator flux oscillates at the mains frequency leading to perturbations on the rotor currents. This paper presents a comprehensive study of the DFIG behavior during voltage dips. Analytical, simulation and experimental results are shown.
Kenji Ikeda - One of the best experts on this subject based on the ideXlab platform.
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structural identification of a nonproportionally Damped System and its application to a full scale suspension bridge
Journal of Structural Engineering-asce, 2005Co-Authors: Tomonori Nagayama, Yozo Fujino, Kenji IkedaAbstract:Ambient vibration measurement is an important tool to evaluate the integrity of in-service structures. The writers apply a new structural identification method to ambient vibration data taken from a full-scale suspension bridge. The method consists of two steps: identification of vibration modes and inverse analysis of structural properties from the identified modes. For modal identification, the method treats the structure as a multi-input-multioutput System, distinguishing noise from true modes and employing ambient vibration measurement. For the identification of structural properties, assumptions on proportionality of damping, previous estimation of structural damping/stiffness, and numerical iteration are not required. Application to the Hakucho Bridge in Hokkaido, Japan, verifies that the method can precisely determine the characteristics of not only the lower modes, but also the higher modes, and can effectively detect changes in the structural properties.
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non iterative identification of non proportionally Damped System from ambient vibration measurement and analysis of dynamic properties of a long span suspension bridge
Doboku Gakkai Ronbunshu, 2003Co-Authors: Tomonori Nagayama, Yozo Fujino, Kenji IkedaAbstract:構造物の健全性や外力・荷重評価に, 使用状態においても計測可能な常時微動を利用することの利点は大きい. 本研究は著者らが以前開発した常時微動データに基づく構造逆解析法の問題点を解泱し, (1) モード同定においてノイズの判別が可能であり, (2) 多入力系を扱え, (3) 構造逆解析においては減衰に関する仮定や構造特性の事前推定そして反復計算を必要としない理論的手法を構築した. さらに, 実構造物の振動計測結果に適用する. 支承や伸縮装置による摩擦力と自励空気力を等価剛性・等価減衰として逆解析を行い, 以前試みた逆解析と比較の上, 本手法の有効性を示した.
G. D. Marques - One of the best experts on this subject based on the ideXlab platform.
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Understanding the doubly fed induction generator during voltage dips
IEEE Transactions on Energy Conversion, 2012Co-Authors: G. D. Marques, Duarte M. SousaAbstract:The doubly fed induction generator (DFIG) is normally controlled with stator-flux orientation. The DFIG is a poorly Damped System with a natural frequency near the grid frequency. This leads to natural oscillations on the stator flux and on other variables. When voltage dips occur, there are oscillations on the stator flux that produces electromotive forces and consequently disturbances on the rotor currents. This paper presents a comprehensive study of the DFIG during voltage dips. The method presented in this paper, valid for symmetric and for asymmetric voltage dips, is based on the classical model of the induction machine with stator flux orientation and neglects only a small part of the cross-coupling terms. The response depends on the design methodology of the proportional-integral inner controllers. Analytical, simulation, and experimental results are shown. The analysis and results can be divided into two sets depending if the voltage dip magnitude is smaller or deeper than 0.5 p.u. © 2012 IEEE.
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EUROCON - Analysis of the DFIG during voltage dips
2011 IEEE EUROCON - International Conference on Computer as a Tool, 2011Co-Authors: G. D. Marques, Duarte M. SousaAbstract:The doubly-fed induction generator (DFIG) is normally controlled with stator-flux orientation. Stator-voltage orientation and other methods like Direct Power Control can also be adopted. It is a poorly Damped System with a natural frequency near the grid frequency. This leads to natural oscillations on the flux and torque and, for stator-flux orientation, in some cases, to instability. When voltage dips occur, the stator flux oscillates at the mains frequency leading to perturbations on the rotor currents. This paper presents a comprehensive study of the DFIG behavior during voltage dips. Analytical, simulation and experimental results are shown.
Tomonori Nagayama - One of the best experts on this subject based on the ideXlab platform.
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structural identification of a nonproportionally Damped System and its application to a full scale suspension bridge
Journal of Structural Engineering-asce, 2005Co-Authors: Tomonori Nagayama, Yozo Fujino, Kenji IkedaAbstract:Ambient vibration measurement is an important tool to evaluate the integrity of in-service structures. The writers apply a new structural identification method to ambient vibration data taken from a full-scale suspension bridge. The method consists of two steps: identification of vibration modes and inverse analysis of structural properties from the identified modes. For modal identification, the method treats the structure as a multi-input-multioutput System, distinguishing noise from true modes and employing ambient vibration measurement. For the identification of structural properties, assumptions on proportionality of damping, previous estimation of structural damping/stiffness, and numerical iteration are not required. Application to the Hakucho Bridge in Hokkaido, Japan, verifies that the method can precisely determine the characteristics of not only the lower modes, but also the higher modes, and can effectively detect changes in the structural properties.
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non iterative identification of non proportionally Damped System from ambient vibration measurement and analysis of dynamic properties of a long span suspension bridge
Doboku Gakkai Ronbunshu, 2003Co-Authors: Tomonori Nagayama, Yozo Fujino, Kenji IkedaAbstract:構造物の健全性や外力・荷重評価に, 使用状態においても計測可能な常時微動を利用することの利点は大きい. 本研究は著者らが以前開発した常時微動データに基づく構造逆解析法の問題点を解泱し, (1) モード同定においてノイズの判別が可能であり, (2) 多入力系を扱え, (3) 構造逆解析においては減衰に関する仮定や構造特性の事前推定そして反復計算を必要としない理論的手法を構築した. さらに, 実構造物の振動計測結果に適用する. 支承や伸縮装置による摩擦力と自励空気力を等価剛性・等価減衰として逆解析を行い, 以前試みた逆解析と比較の上, 本手法の有効性を示した.
Kamaldeep Singh Lote - One of the best experts on this subject based on the ideXlab platform.
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Understanding demand volatility in supply chains through the vibrations analogy—the onion supply case
Logistics Research, 2013Co-Authors: Sanjay Sharma, Kamaldeep Singh LoteAbstract:Fluctuating demand for goods in many situations is not caused by genuine discontinuities in the consumption or usage of those goods. Basic food products, for example, are consumed at relatively stable rates. But disruptions in their supply—real or imputed—may cause demand volatility with consequences of unwanted price fluctuations. In this paper, the vibrations analogy is proposed to better understand this phenomenon. Various alternative scenarios of damping vibrations are discussed in this paper, viz., underDamped, overDamped, and critically Damped System. An interpretation of those scenarios is offered with respect to their meaning to supply chain management and illustrated through the case of the onion supply. The proposed analogy is found to be useful in explaining and taking appropriate steps for improvement in such cases.
