This paper presents a comparative analysis of 2- and 3-D methods for computing the electromagnetic field generated by overhead transmission lines operating at the power frequency. The study focuses on the catenary effect of cables and the effect of electric charges and currents present in tower elements when computing the electric field on the cables' surface and the electric and magnetic fields near the earth's surface. Results for a typical three-phase 138-kV line are presented as well as the proper range of the application for a modified and fast 2-D solution.

Comparative Analysis of 2- and 3-D Methods for Computing Electric and Magnetic Fields Generated by Overhead Transmission Lines

Measurements and predictions of electric and magnetic fields from power lines

In this paper support vector machine (SVM) has been used for optimization of electric field along the support insulators used in high voltage (HV) systems. To illustrate the effectiveness of SVM in optimizing electric field problems, two axi-symmetric cases have been considered one having an insulator with a contour that is quarter ellipse and the second one having a porcelain core solid insulator. The training and the test data for the SVM have been prepared by electrostatic field computation using indirect boundary element method (BEM). It is observed that once the SVM is trained it is able to give results with mean absolute error of less than 1.5% when compared with the analytically obtained results. The SVM designed for insulator contour optimization is first trained with the results obtained from electric field computation for some predetermined contours of the arrangements under consideration. Then the trained SVM is used to produce an optimized insulator contour in such a way that the desired stress distribution can be obtained on the insulator surface. The results obtained from the present study show that the trained SVM is adequately efficient to optimize insulator contours in order to have the desired stress distribution along the insulator surface

Optimization of support insulators used in HV systems using support vector machine

Optimization of contours of three dimensional electrode-spacer arrangements used in gas insulated systems (GIS) has been carried out by ANN aided genetic algorithm (GA) to obtain desirable electric stress distribution along the insulator surface. Two cases have been studied and reported in detail. Multilayer feed-forward neural networks with error back-propagation algorithm have been applied to accelerate the execution of GA loop. The training and the test data have been prepared by means of electric field calculations using indirect boundary element method (BEM). The results show that optimized contours have been obtained with acceptable degree of accuracy with the help of GA aided by trained ANN.

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Electrode-spacer contour optimization by ANN aided genetic algorithm

Electrical-field distribution along the insulator surface strongly depends upon the contour design, besides the effect of pollution. The insulator contour should be designed to reach a desired uniform and minimal tangential field to increase the onset voltage of surface flashover. In this paper, with the charge simulation method (CSM) integrated, the dynamically adjustable genetic algorithm (DAGA) approach is proposed for contour optimization of a suspension insulator. The aim of the contour optimization is to minimize and make the tangential electric field uniform and to minimize the size of the insulator, subject to design constraints. In the proposed approach, the cubic spline function based on control (or contour) points on the insulator surface is optimized to derive the desired contour. The results show that a rather uniform and minimal tangential field distribution with a smaller suspension insulator can be obtained through the proposed approach in comparison with the commercial insulator practically deployed in transmission systems.

Contour Optimization of Suspension Insulators Using Dynamically Adjustable Genetic Algorithms

Computer methods have become an essential tool for the design of high voltage equipment, in order to utilize the electric field as well as possible. The paper describes new algorithms based on the boundary element method for analyzing electric field distributions of high voltage apparatus. These algorithms regard surface elements composed of segments of realistic technical electrode and insulator surfaces. The method is illustrated by some examples from industry. >

F. Gutfleisch

Papers

Calculation of high-voltage fields by means of the boundary element method