Research on the Corrosion Impact of DC Grounding Electrode Current on Surrounding Tower Grounding Systems

Abstract

With the widespread application of high-voltage direct current (HVDC) transmission technology, the corrosion of grounding systems in transmission towers caused by the ground current of DC grounding electrodes has become increasingly significant. Currently, existing research, both domestically and internationally, has not fully considered the impact of non-uniform soil conditions on the distribution of DC currents in towers. To address this gap, this study employs the CDEGS simulation software to construct uniform and non-uniform soil models, systematically analyzing the influence of soil resistivity, soil layer thickness, and different grounding electrode configurations on the distribution of DC currents and corrosion characteristics in tower grounding systems. The results reveal that under uniform soil conditions, the ground current of the tower closest to the grounding electrode increases with soil resistivity and exhibits significant spatial attenuation characteristics. In horizontally layered soil models, when the upper soil layer has lower resistivity, the ground current decreases with increasing upper layer thickness, whereas the opposite trend is observed when the upper layer has higher resistivity. As the upper soil resistivity gradually exceeds that of the lower layer, the ground current tends to saturate, while changes in lower layer resistivity have a more pronounced impact on current distribution. Furthermore, the current density distribution varies significantly among different grounding electrode configurations. Type C grounding electrodes exhibit the lowest localized corrosion, while Type B electrodes suffer the most severe corrosion at the ends of their rays. These findings provide technical support for the optimized design and corrosion protection strategies of transmission tower grounding systems, enhancing their operational safety and reliability.