Nebojša B. Raičević

Hybrid Boundary Element Method for Multi-Layer Electrostatic and Magnetostatic Problems

Abstract A hybrid numerical method is proposed involving a successful combination of the equivalent electrodes and boundary element method. Electric field and electric potential distribution are determined by using both equivalent electrodes and equivalent charges. Greens function for potential of the charge per unit length, placed in free space, on the boundary of two dielectrics, is used. Magnetic-field distribution is determined by applying equivalent currents through magnetic vector potential and substitution of Amperes microscopic currents with total currents. The accuracy of the developed method is highlighted with some simple numerical examples.

Electrical field and potential distribution at the cable termination

The results for electrical field and potential distribution at the coaxial cable termination, having exponential or ellipsoidal form, obtained by the equivalent electrodes method, are presented in this paper. Equivalent electrodes (EE) are appointed on the end of coaxial cable, where the edge effect exists. To a great distance from the termination, inside the cable, it may be considered that the field is approximately homogenous and the charge distribution is continuous. It is possible to determine the potential as superposition of two components: the first one originates from continuous distribution of the electrical charge, and the second one from EE.

Equivalent Electrode Method Application on Anisotropic Micro Strip Lines Calculations

Theoretical analysis of a micro strip line, assuming TEM mode propagation is carried out in the paper. Micro strip lines are significant parts of multi-layer integrated circuits. Electric field and electric potential distribution, effective dielectric permittivity and characteristic impedance of transmission line are determined applying equivalent electrodes method (EEM). The Greens function of the uniform charge per unit line length is used, placed in free space, above both an anisotropic medium and grounded plate. Due to combination of numerical and analytical determination, this is a hybrid method.

Hybrid Boundary Element Method and Quasi-TEM Analysis of Two-Dimensional Transmission Lines—Generalization

Abstract The hybrid boundary element method, based on the equivalent electrodes method and the boundary element method, is presented in this article. This method is applied on several examples for calculating the characteristic impedance of transmission lines. It should be emphasized that the combination of the equivalent electrodes method and a new variant of the boundary element method can be efficiently implemented in quasi-transverse electromagnetic analysis of transmission lines without loss of accuracy. All results for the characteristic impedance of the observed transmission lines are compared to corresponding ones obtained by the finite-element method.

A Novel Approach to the Positive DC Nonlinear Corona Design

Abstract This article is aimed at proposing one very simple method for electric field and potential distribution determination in the case of large charges at electrodes surfaces when the electric field takes a very high value and induces corona discharges. The method also enables capacitance calculation as well as a dimension of the corona region. By using appropriate analogies, parameters of grounding systems driven by high currents can also be determined.

Interaction magnetic force calculation of radial passive magnetic bearing using magnetization charges and discretization technique

Calculation of the interaction magnetic force between two ring permanent magnets with radial magnetization is presented in the paper. Such configuration corresponds to a radial passive magnetic bearing. The simple and fast analytical approach is used for this calculation based on magnetization charges and discretization technique. The results for interaction magnetic force obtained using proposed approach are compared with finite element method (FEM). The advantage of presented approach is its simplicity and time efficiency since only complete elliptic integrals of the second kind are used and other additional integrations are avoided in this calculation.

Analysis of a MV XLPE cable termination design with embedded electrodes

Insertion of embedded electrodes (EEs) inside a MV XLPE cable termi- nation strongly affects electric field around the terminati on and accordingly must be carefully considered. In this paper, influence of embedded e lectrodes on voltage distri- bution in some constructions of the 20 kV cable terminations was analyzed. Different options were considered for a specific number of the EEs along the cable insulation surface, taking into account possible effects of floating or grounded EEs, their differ- ent position and separation. In every option, a basic method of stress relieving with resistive layer over the end of semi conducting screen and primary cable insulation was applied. Reference design was a cable termination without EE. Its voltage dis- tribution, total electric field and tangential component we re observed for comparison. The stress relief materials, in the shape of pads or tubes, we re used. Their properties were kept the same in all constructions. Voltage distributi on was monitored, starting from the end of the primary cable insulation in the vicinity of the phase conductor and ending at the cable insulation attached to the semiconducting screen end at ground potential. The different design options were experimentally verified.

One Method for Strong Electric Field Reduction at Cable Terminations and their Influence on Environment

Cable terminations and cable joints belong to the most sensitive and the weakest parts of electrical power lines. At the places of cable connecting and ending, the exterior cover is removed, and the radial character of electric field is disturbed. Because of high voltage, the inhomogeneous electric field exists on those parts of the cable, having the highest intensity at the ends of the covers, or screen. Using additional grounded or floating electrodes, it is possible to control and decrease the intensity of the electric field, depending on their position, which has strong influence on the electric field strength. The procedure for determining optimal length and position of the grounded electrode related to the cable end is presented in the paper. The simplest calculation can be carried out using equivalent electrodes method (EEM), and that obtains very high accuracy of the calculated values.

Reducing the impact of ELF electromagnetic fields of HV power cables on the environment by modeling the cable accessories

Purpose – Underground cables can produce higher electromagnetic fields directly above them than an overhead line. The majority of cable failures on distribution system are caused by defects in the cable accessories. Nowadays, significant research has been carried out worldwide into examining whether electricity, and in particular, the presence of electric and magnetic fields have an adverse impact on health, especially the occurrence of cancer and childhood leukemia. The purpose of this paper is to optimize the electric field distribution in underground cable accessories. This reduces the impact of the harmful effects of the fields on living beings and humans. Design/methodology/approach – Cable terminations and joints are designed to eliminate the stress concentration at the termination screen to avoid the breakdown of the cable and high values of electric field at these points. Any improvement in the cable termination and joints construction is of great interest. There are several methods for the soluti...

TEM analysis of multilayered transmission lines using new hybrid boundary element method

Theoretical analysis of multilayered transmission lines assuming TEM propagation mode is carried out in the paper. Effective dielectric permittivity and characteristic impedance of the transmission line are determined applying the new hybrid boundary element method (HBEM) based on the equivalent electrodes method (EEM). All results are compared with the exact analytical, or the finite element method (FEM) solutions.