Lightning Transients in Wind Turbines: A Study on How to Segmentize the Tower, Blades, and Grounding Rods

Segmenting Wind Turbine's (WT) tower and blades has been widely used to increase the accuracy of lightning transient simulations. However, the impact of segmentation on precision and the optimal number of segments required for a specific accuracy level have not been thoroughly investigated. In this paper, at first, a formulation for calculating the characteristic impedance of blades' down conductors is analytically derived and verified based on the experimental data. Then, the electrical parameters of the WT's blades, as nonuniform transmission lines, are accurately calculated. A comprehensive analysis is then performed to examine how the number of segments in WT's blades, tower, and grounding systems affects transient voltages and currents created by lightning strikes. The investigation focuses on assessing the effects of the number of segments in terms of the generated overvoltage across various components, the Ground Potential Rise (GPR) values, and the energy absorbed by Surge Arresters (SA). The numerical studies reveal that the quantity of segments for each component significantly influences the outcomes of the lightning strike. For instance, the number of tower's segments mostly affects the overvoltage at the generator's terminal, while the number of ground's horizontal rod segments has the most impact on GPR. This study provides valuable insights into tailoring segmentation strategies for WT components, paving the way for more effective lightning protection simulation and design.