Author
V. Jayashankar
Bio: V. Jayashankar is an academic researcher from Indian Institutes of Technology. The author has contributed to research in topics: Electric power system & AC power. The author has an hindex of 2, co-authored 3 publications receiving 10 citations.
Topics: Electric power system, AC power, Voltage, Grid, Equivalent circuit
Papers
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01 Oct 2008TL;DR: In this paper, the authors compared the performance of an annular linear induction pump (ALIP) as predicted by an equivalent circuit model with that predicted by a finite element model.
Abstract: An EM (electromagnetic) pump is employed to transport liquid metal in applications like metal industries and metal cooled atomic reactors, which are in chemically active and high temperature environment. One type of EM pump is the annular linear induction pump (ALIP), which uses liquid sodium with high electrical conductivity as a coolant. In this paper we compare the performance of ALIP as predicted by an equivalent circuit model with that predicted by a finite element model. It is shown that the finite element model gives pointers to refinement that may be necessary to improve prediction accuracy through the equivalent circuit approach. This paper also presents a parametric study of the system in an attempt to find ways of improving the pump performance.
8 citations
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01 Oct 2008TL;DR: In this article, the voltage impact of wind farms on weak grids is studied using a generic test system and the voltage at the point of interconnection (POI) of the wind farm to the grid is analyzed for different values of grid X/R ratios.
Abstract: The voltage impact of wind farms on weak grids is studied using a generic test system The size of the wind farm is taken as 20% of the grid short circuit MVA to characterize weak grids The voltage at the point of interconnection (POI) of the wind farm to the grid is analyzed for different values of grid X/R ratios It is shown that reduction of real power injection at POI brings the voltage at POI within permissible values for the entire range of X/R ratios A pumped storage unit or a variable frequency transformer as an asynchronous inter connector is suggested to realize this Complete modeling and simulation of the proposed network topologies are given The results are discussed with reference to the Indian power system
3 citations
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01 Oct 2008TL;DR: In this article, variable frequency transformers (VFTs) were proposed as an effective means of interconnecting synchronous or asynchronous regions to enhance wind penetration, and the steady state stability limits of the system were improved with VFT as inter connectors.
Abstract: For grids of low X/R ratios voltage control through active power is effective in reducing the voltage at the point of interconnection of wind farms to grid Active power voltage control can be achieved using energy storage schemes or inter connectors In this paper we propose variable frequency transformers (VFT) as an effective means of interconnecting synchronous or asynchronous regions to enhance wind penetration It is shown that the steady state stability limits of the system are improved with VFT as inter connectors Also the performance of the VFT under open circuit and short circuit conditions are evaluated
2 citations
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TL;DR: Using the series circuit, the performance of the SLIM was assessed in a similar manner to a rotating induction machine and a 4-kW SLIM prototype was tested, which validated the simulation technique.
Abstract: The derivation of the equivalent circuit for a single-sided linear induction motor (SLIM) is not straightforward, particularly if it includes longitudinal end effects from the cut-open primary magnetic path, transversal edge effects from the differing widths between the primary lamination and secondary sheet, and half-filled primary slots. This paper proposes an improved series equivalent circuit for this machine. The longitudinal end effects are estimated using three different impedances representing the normal, forward, and backward flux density waves in the air gap, whose two boundary conditions are deduced by introducing the conception of magnetic barrier surface. The transversal edge effects are accounted for by correction coefficient Kt and air-gap flux density correction coefficient Kb. Using the series circuit, the performance of the SLIM was assessed in a similar manner to a rotating induction machine. A 4-kW SLIM prototype was tested, which validated the simulation technique.
122 citations
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TL;DR: In this paper, the authors explored the possibility of synchronous generator based wind energy generation system feeding an isolated load using a latest power transmission technology i.e. variable frequency transformer (VFT).
19 citations
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TL;DR: In this article, the design variables of an annular linear induction electromagnetic pump (ALIP) for SFR thermal hydraulic experimental loop were analyzed magnetohydrodynamically and the developed pressure was found to be a function of design variables, including pump core length, inner core diameter and flow gap.
14 citations
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01 Dec 2014
TL;DR: The proposed method does not employ any power electronic based interface for grid integration of SG based WEGS and hence does not produce harmonics and the control of the proposed method is simple.
Abstract: Conventional grid connected synchronous generator (SG) based wind energy generation system (WEGS) incorporates sophisticated power electronic control system in it which produces harmonics and this deteriorates the quality of output power. Hence, this paper presents a new method for grid integration of SG based WEGS using variable frequency transformer (VFT). The proposed method does not employ any power electronic based interface for grid integration of SG based WEGS and hence does not produce harmonics. Moreover, control of the proposed method is simple. In order to realize the proposed scheme, a digital simulation model of the proposed method has been developed under MATLAB/ Simulink environment. The power flow from the SG to the grid using the model has been studied and its results have been discussed.
12 citations
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29 Jan 2014
TL;DR: In this article, Pression et al. proposed a model for the induction of a quatrieme generation of reacteurs nucleaires, which can be seen as an extension of the one proposed in this paper.
Abstract: Les preoccupations actuelles concernant l'exploitation securitaire des centrales nucleaires existantes et la conception d’architectures speciales envisagees pour la quatrieme generation de reacteurs nucleaires se combinent avec l’interet plus prononce pour l'efficacite et la fiabilite de l'equipement d'un systeme energetique. Cela fait que dans un souci de meilleure comprehension et optimisation basee sur des moyens modernes de conception assistee par l’ordinateur, l'etude de differentes parties de ces systemes fait de plus en plus l’objet de recherches approfondies. . Parmi les types proposes pour la quatrieme generation de reacteurs nucleaires font partie ceux ayant comme agent de refroidissement les sels fondus, respectivement le sodium fondu. En raison de leurs proprietes physiques, les sels fondus et le sodium liquide ont le potentiel d'etre deplaces par les pompes electromagnetiques. Cet ouvrage est a la fois une etude approfondie des phenomenes qui se produisent en raison de l'ecoulement du fluide dans le champ electromagnetique d’une pompe electromagnetique - interaction magnetohydrodynamique - et un rapport sur les capacites et les avantages des outils informatiques modernes pour faciliter la conception et l'optimisation des pompes electromagnetiques. Afin d’atteindre l'objectif principal de la these, notamment une meilleure comprehension des phenomenes interdependants specifique a l’operation des pompes electromagnetiques, deux objectifs secondaires ont ete consideres. Le premier objectif concerne la pleine exploitation des modeles electromagnetiques numeriques en elements finis afin d'obtenir autant d'informations que possible sur le comportement des pompes electromagnetiques, dans l’hypothese ou on ne tient pas compte de l'ecoulement des fluides. Le deuxieme objectif etait la construction des modeles numeriques qui reunissent l’electromagnetisme et la dynamique des fluides, respectivement des modeles numeriques qui regroupent les deux phenomenes caracterisant l’ecoulement magnetohydrodynamique dans les canaux des pompes electromagnetiques. Dans l'etude dediee au pompage electromagnetique de sels fondus, la these met en evidence des problemes specifiques lies a la generation de forces electromagnetiques dans les fluides faibles conducteurs d'electricite et fournit des resultats sur les applications ou le pompage electromagnetique de sels fondus peut etre efficace. A l’aide des modeles electromagnetiques nous avons obtenu des informations importantes sur l'influence du nombre de poles electromagnetiques et de la frequence d’alimentation sur la caracteristique Pression - Vitesse des pompes annulaires a induction. Ils ont ete analyses le phenomene de blindage cree par les parois metalliques - avec des repercussions negatives sur les performances de la pompe, les effets de freinage exerces a l'entree et a la sortie du canal de la pompe et la relation entre la capacite de surcharge hydrodynamique et la caracteristique Pression - Vitesse des pompes a induction. Une section speciale a ete consacree a l'analyse de la dependance de la force electromagnetique du temps et de l’espace et a l’etude de non-uniformitees des quantites de nature electromagnetique en direction azimutale dans les pompes annulaires a induction.Dans le chapitre qui traite de l'interaction magnetohydrodynamique a base de modeles couples, ils sont proposes deux modeles qui couplent l'electromagnetisme et l’ecoulement. Ils sont presentes les avantages des modeles couples, en matiere de la precision des resultats, par rapport aux modeles electromagnetiques. Il est egalement presente l'evolution des profils de vitesse, de densite de force et de courant sous l'influence du champ electromagnetique et de l’ecoulement de sodium a vitesses differentes. Les contributions de la these sont completees par des observations importantes sur les methodes de travail et les logiciels utilises tout au long de l'etude.
7 citations