1,721,142 research outputs found
Fast analytical computation of power-line magnetic fields by complex vector method
No full textThe electromagnetic environment related to electric power installations is typically evaluated by numerical integration methods. Numerical techniques, although powerful, are not well suited for assessing the dependence of the field strength on electric and geometric parameters. In this paper, a fast procedure to analytically evaluate power-line magnetic fields, based on complex vectors, is proposed. The use of complex algebra greatly simplifies analytical calculations compared to other approaches proposed in literature, allowing also complex conductor arrangements to be taken into account. A general formula for the magnetic-field intensity of any multiphase single-circuit line configuration is obtained. An expression for practical three-phase line configurations is simply derived as a particular case of the general formula. The proposed approach is then extended successfully to double-circuit lines, taking the load differences between circuits into account. Approximate formulas are validated by comparing magnetic flux density values with those computed from the general expression
Fast Construction of Matching Constraints for Three-Dimensional Domain Decomposition Methods with Non-Matching Grids
No full textAnalysis and design of conductive shields for the reduction of stray ELF magnetic fields produced by MV/LV substations
No full textAnalytical calculation of the environmental magnetic field generated by double circuit power lines
No full textIn this work approximate formulae are
presented for computing the magnetic field intensity
generated by power lines. Original expressions are
given for double circuit lines in both super-bundle and
low-reactance conductor phasing. These expressions can
be used for assessing directly the right-of-way width of
transmission lines related to maximum magnetic field
exposure levels which may be efficiently used in
environmental impact analysis. The accuracy of the
approach is demonstrated by comparison with (exact)
numerical computations based on the Biot-Savart’s law
Analytical calculation of the environmental magnetic field generated by single and double circuit power lines
No full textModelling of Thin Conductive Screens for ELF Magnetic Field Attenuation by Finite Element and Integral Methods
No full textMitigation of ELF (Extremely Low Frequency) magnetic fields is often performed by means of highly conductive laminar shields. Usually 2D codes are used for ELF shield design purposes in order to reduce computing requirements. In this paper it is shown that a 3D integral method can be used instead, providing a much higher accuracy with similar computational costs. It consists of an original procedure based on the Cell Method able to model properly the actual geometry of the arrangement. Comparisons between the two methods are applied in some typical configurations. The discrepancy between 2D and 3D approaches is analyzed as a function of shield shape (flat and U-shaped) and dimensions (thickness, width and length). The 3D integral procedure is used then for assessing the shield performance of flat and U configurations. Eventually, the same procedure is successfully applied to analyze a real case shield installed in a 20 kV/400 V substation
Enforcing Lumped Parameter Excitations in Edge-Element Formulations by Using a Fast Iterative Approach
No full textIn order to couple external circuits to edge-element discretized electromagnetic models, with full field equations, global constraints involving voltages or currents need to be enforced. There is no canonical way to impose a voltage or a current without additional modeling information on the distribution of field sources that rely on topological concepts. In this article, a fast solution of field sources within massive conductors in static and dynamic problems is proposed. Global basis functions, required to cope with non-trivial coil topologies, are directly generated by an iterative solver rather than pre-computing source fields, e.g., by tree–cotree decomposition
Domain Decomposition With Non-Conforming Polyhedral Grids
Full text linkA novel mortar approach for the domain decomposition of field problems discretized in terms of nodal variables by the cell method is here proposed. This approach allows the use of both arbitrary polyhedral meshes and non–conforming discretizations, without limitations or complications due to the mesh type or the model geometry. Therefore, it provides a new domain decomposition method that can be practically used in engineering applications for coupling different parts of a model, which can be independently discretized and then reassembled together. More precisely: 1) Any part of the computational domain is first separately modeled in order to assess the mesh type and size that are best suited for ensuring an accurate local field reconstruction; 2) The different discretized parts can be combined together in order to obtain an accurate solution of a composite problem, while maintaining the local discretizations already determined. As a main advantage over existing mortar approaches, the algebraic structure of the final matrix system—derived by the cell method discretization—is not altered by the introduction of mortar interface conditions. As a result, the same preconditioning and iterative solver strategy can be extended as is to the proposed mortar method. This approach is validated by a convergence analysis on an analytical test case and its effectiveness for practical applications is assessed on a real–sized engineering problem
Efficient 3-D Domain Decomposition with Dual Basis Functions
No full textNovel basis functions are proposed for enforcing continuity constraints in 3-D elliptic problems discretized by non-conforming domain decomposition methods. The major advantage over standard coupling methods is that the projection matrix, mapping degrees of freedom from master to slave surface, can be constructed with minimum computing effort since the slave matrix is diagonal. The accuracy of matching conditions and convergence properties of the method are tested on a benchmark problem
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