MODELING OF THE ELECTRIC FIELDS IN THE VICINITY OF THE CONDUCTIVE LIGHTNING RODS

Abstract

The aim of the work is to develop a method for more accurate calculation the electric field (EF) distribution in the systems with conducting lightning rods, ensuring that the electric field strengths and potentials can be found at the grid spatial step proportional to the rod length and not to its radius. Methodology: a method of the electric field calculation in the vicinity of conducting rods with a large ratio of length to radius: more than 102–103 is described. The proposed method is based on the finite integration technique and usage of information on the nonlinear decrease of the EF strengths and potentials in the directions perpendicular to the rod axis. Results: it is shown that the best match with analytical solutions can be achieved by obtaining the difference coefficients at the nodes surrounding the rod with the help of integrating expressions for the EF strength of a conductive ellipsoid upon electric potential over the computational grid cell surfaces. Practical value: as a result of the proposed method usage, it become possible more accurate calculation of the electric field strength in the zone around a rod under potential or a rod in a homogeneous EF when applying a grid, the step of which is comparable with its length, not its radius. Originality: usage of the proposed method for calculation of the EF strength in the vicinity of the conducting rods, taking into account nonlinear character of the EF strength and potential decrease in the close vicinity of the rod with the help of analytical expressions for the EF of an elongated conducting ellipsoid upon electric potential, reduces relative errors of the EF strength calculation in the zone around the rod and above its tip from 27 % to 3 % and less. In this case, a spatial step is chosen proportional to the length of the rod, and not to its radius. An example of the electric field strength calculation in lightning storm conditions is presented.