Effect of the Time-Varying Soil Resistivity on the Performance of the Protective Devices under the Electromagnetic Fields from Lightning

Abstract

Background/Objectives: Transients in the overhead power lines due to lightning events can be caused by both direct and indirect strokes. Both direct and indirect events can cause severe issues in the power system. Methods/Statistical Analysis: The frequency of the indirect lightning return strokes is more when we consider the lightning studies on the overhead lines considering the height of the present distribution and transmission lines. Lightning-induced voltages on the overhead transmission lines have been computed using the finite-difference time-domain method. A source of lightning surge wave on power transmission lines is modelled as a double exponential wave using Modified Transmission Line with Exponential current decay (MTLE) model. Computation of overvoltage caused by lightning waves is calculated for single conductor lines with and without considering the soil reflections taking into account the dynamic characteristics of soil under lightning conditions. Findings: Computations are carried out for the various configurations of multi-conductor transmission lines. The effectiveness of the protective devices such as shield wires is also studied here. The surge arrester modelling is carried out and the design parameters for these protective devices are finalised after optimization. MATLAB and PSCAD software are used for simulation. Triangular configuration gave a better response to lightning than the horizontal and vertical configuration. Applications/Improvements: A 3D approach on the problem with use of COMSOL will give a better insight on the field pattern.