Universidade da Coruña. UDCDspace
(405 recursos)
UDCDspace é o repositorio dixital da Universidade da Coruña, un sistema que proporciona de xeito estable e seguro a preservación de documentos dixitais produto da actividade científica e institucional da UDC, e facilita a súa accesibilidade en Internet.
Mostrando recursos 1 - 19 de 19
1.
Una formulación numérica general para el cálculo y diseño de tomas de tierra
en grandes instalaciones eléctricas - Colominas Ezponda, Ignasi; Navarrina Martínez, Fermín; Casteleiro Maldonado, Manuel
La puesta a tierra de una instalación eléctrica es imprescindible para garantizar su seguridad
cuando tienen lugar situaciones de fallo. Para su correcto análisis y diseño se requiere
la determinación de una serie de magnitudes tales como el cálculo de la resistencia equivalente
de la toma de tierra y la distribución del potencial originado en la superficie del terreno como
consecuencia de una derivación de corriente al mismo. Tradicionalmente, los estudios sobre el
cálculo de tomas de tierra se han planteado con el fin de obtener fórmulas sencillas y rápidas (a
partir de mediciones experimentales en modelos de laboratorio o como resultado de la experiencia
acumulada por...
2.
A boundary element formulation for the substation grounding design - Colominas Ezponda, Ignasi; Navarrina Martínez, Fermín; Casteleiro Maldonado, Manuel
A Boundary Element approach for the numerical computation of substation grounding systems is presented. In this general formulation, several widespread intuitive methods (such as Average Potential
Method) can be identified as the result of specific choices for the test and trial functions and suitable assumptions introduced in the BEM formulation to reduce computational cost. While linear and parabolic
leakage current elements allow to increase accuracy, computing time is drastically reduced by means of
new completely analytical integration techniques and semi-iterative methods for solving linear equations
systems. This BEM formulation has been implemented in a specific Computer Aided Design system for
grounding analysis developed in the...
3.
A boundary element numerical approach for earthing grid computation - Colominas Ezponda, Ignasi; Navarrina Martínez, Fermín; Casteleiro Maldonado, Manuel
Analysis and design of substation earthing involves computing the equivalent resistance of grounding systems, as well as distribution of potentials on the earth
surface due to fault currents [1,2]. While very crude approximations were available
in the sixties, several methods have been proposed in the last two decades, most
of them on the basis of intuitive ideas such as superposition of punctual current
sources and error averaging [3,4]. Although these techniques represented a significant improvement in the area of earthing analysis, a number of problems have been
reported; namely: large computational requirements, unrealistic results when segmentation of conductors is increased, and uncertainty in the margin...
4.
High Order Shape Design Sensitivity: A Unified Approach - Navarrina Martínez, Fermín; López Fontán, Santiago; Colominas Ezponda, Ignasi; Bendito Pérez, Enrique; Casteleiro Maldonado, Manuel
Three basic analytical approaches have been proposed for the calculation of sen-
sitivity derivatives in shape optimization problems. The first approach is based on
differentiation of the discretized equations [1-3]. The second approach is based on
variation of the continuum equations [1,4,5] and on the concept of material deriva-
tive. The third approach [6] is based upon the existence of a transformation that
links the material coordinate system with a fixed reference coordinate system. This
is not restrictive, since such a transformation is inherent to FEM and BEM imple-
mentations.
In this paper we present a generalization of the latter approach on the basis of a
generic unified procedure...
5.
Computer analysis of earthing systems in horizontally or vertically layered soils - Colominas Ezponda, Ignasi; Gómez Calviño, Javier; Navarrina Martínez, Fermín; Casteleiro Maldonado, Manuel
The main objectives of grounding systems are to guarantee the personal safety, the equipment protection and the continuity of the power supply. To attain these goals, the potential distribution on the earth surface and the equivalent resistance of the earthing system have to be determined in a reliable an efficent way. In this paper, we present a numerical technique based on a Boundary Element Method for grounding analysis of horizontally and vertically latered soils. The feasibility of the proposed method is demostrated by means of its application to a real grounding grid considering different types of soilo models.
8.
SUPG stabilized finite element resolution of the Navier-Stokes equations: application to water treatment engineering - Rodríguez-Vellando Fernández-Carvajal, Pablo; Puertas Agudo, Jerónimo; Colominas Ezponda, Ignasi
In this paper an analysis of the viscous incompressible flow has been carried out, from the very definition of the governing equations, up to the resolution of some practical problems, passing through the comprehensive study of the stabilized finite element techniques used in this resolution. As a consequence of this analysis, a code based upon a realistic interpretation of the forces has been written, wich allows for the modelling of the open channel flow, with optimum results in the resolution of some benchmark and real flow problems related with the wastewater industry.
9.
Aplicación de una formulación de elementos finitos para la resolución del flujo en unidades de proceso de aguas residuales - Rodríguez-Vellando Fernández-Carvajal, Pablo; Puertas Agudo, Jerónimo; Colominas Ezponda, Ignasi; Suárez López, Joaquín; Gil de Bernabé, José
En el presente trabajo se exponen los resultados de la aplicación de una formulación numérica
propuesta por los autores, en la resolución de varios problemas de flujo relacionados con el tratamiento
de aguas residuales. La formulación expuesta está basada en el Método de los Elementos
Finitos, y resuelve las ecuaciones de Navier-Stokes que gobiernan el flujo viscoso incompresible.
El desarrollo de este código permite modelar de manera adecuada el flujo viscoso incompresible y
es capaz de evaluar el comportamiento del agua en depósitos y canales de las estaciones de tratamiento
de aguas, permitiendo así conseguir un funcionamiento óptimo de éstas, gracias a la modificación
de los parámetros...
10.
On the Galerkin formulation of the smoothed particle
hydrodynamics method - Cueto-Felgueroso Landeira, Luis; Colominas Ezponda, Ignasi; Mosqueira Martínez, Gonzalo; Navarrina Martínez, Fermín; Casteleiro Maldonado, Manuel
In this paper, we propose a Galerkin-based smoothed particle hydrodynamics (SPH) formulation with
moving least-squares meshless approximation, applied to free surface flows. The Galerkin scheme
provides a clear framework to analyse several procedures widely used in the classical SPH literature,
suggesting that some of them should be reformulated in order to develop consistent algorithms. The
performance of the methodology proposed is tested through various dynamic simulations, demonstrating
the attractive ability of particle methods to handle severe distortions and complex phenomena.
11.
Resolution of the flow in clarifiers by using a stabilized finite element method - Rodríguez-Vellando Fernández-Carvajal, Pablo; Puertas Agudo, Jerónimo; Colominas Ezponda, Ignasi
The description of the flow that takes place in clarifiers and other wastewater treatment basins may be a powerful tool to attain an optimum design of these structures, in order to make the most of the wastewater treatment plant resources. Some authors have attempted so by making use of the potential flow or the Stokes equations. Whan these simplifications are used, an approximation of the flow for slow creeping conditions is obtained, but only the resolution of the all-term-including Navier-Stokes equations will allow us to detect the real streamlines and the vortices that show up for even very slow water...
13.
Boundary element formulation for the analysis of transferred
potentials in electrical installations - Colominas Ezponda, Ignasi; Navarrina Martínez, Fermín; Casteleiro Maldonado, Manuel
In this work we present a BEM numerical formulation for the analysis of a common problem in electrical engineering practice, that is, the
existence of transferred earth potentials in a grounding installation [IEEE Guide for safety in AC substation grounding (2000)]. The transfer
of potentials between the grounding area to outside points by buried conductors, such as communication or signal circuits, neutral wires,
pipes, rails, or metallic fences, may produce serious safety problems [Comput Methods Appl Mech Eng, 174 (1999) p. 73]. Thus, in this paper
we summarize the BE numerical approach and we present a new technique for the transferred potential analysis. Finally,...
14.
Analysis of transferred earth potentials in grounding systems: a BEM numerical approach - Colominas Ezponda, Ignasi; Navarrina Martínez, Fermín; Casteleiro Maldonado, Manuel
In this work we present a numerical formulation for the
analysis of a common problem in electrical engineering
practice, that is, the existence of transferred earth potentials
in a grounding installation [1]. The transfer of potentials
between the grounding area to outer points by buried
conductors, such as communication or signal circuits, neutral
wires, pipes, rails, or metallic fences, may produce serious
safety problems [2]. In this paper we summaryze the
BE numerical approach and we present a new technique for
the transferred potential analysis. Finally, we show some
examples by using the geometry of real grounding systems
in different cases of transferred potentials.
1.
