Determination of current and temperature distribution in overhead conductors by using electromagnetic-field analysis tools

This paper discusses the issue of skin-effect impact on a current's distribution. It presents an analytical approach for determining temperature distribution by using the Electromagnetic Field Analysis Tool's two-dimensional (2-D) program (ELEFANT 2D) over the cross sections of tube-type conductors. Using this implemented model, the authors determine the conductor's current density by taking into account the skin-effect impact on a multilayered bare conductor by the overhead power transmission lines of the ACSR 490/65 mm/sup 2/ type, and the optical cable of the optical ground wire (OPGW) type. An ELEFANT 2D is given an enabling determination of temperature distribution over the tube-type conductor cross section. The authors have developed, using this program, a computerized mathematical model for temperature determination by considering the skin effect in a multilayer ACSR 490/65 mm/sup 2/ conductor, and the optical cable of the OPGW type. The results show temperature distribution in individual layers of the ACSR 490/65 mm/sup 2/ conductor and the OPGW cable by adiabatic heating at different short-circuit currents.

I. Introduction

Calculating the temperature state of heated overhead line conductors is usually based on uniform current distribution over the conductor's cross section with no regard to the skin effect or any other effect (such as, for instance, the effect of the proximity phenomenon). Fig. 1. Skin effect with a single conductor. In reality, the current, or more precisely, the current density distribution over the conductor cross section is unequal due to the skin effect [1]. This effect has some relevance in the uneven heating of individual layers in conductors of the multilayer type. Calculations of heat gain for the adiabatic heating state are made by means of a simplified approach. In such an approach, the overall Joule heat is assumed to be used for the conductor's temperature rise and both heat loss during the time when short-circuit occurrence and skin effect are neglected. The results of the laboratory research are very helpful. They enable comparisons between the results of laboratory investigations and the results obtained through temperature measurements made during heating under nonadiabatic conditions, during which these effects have already been taken into account.