Improved Prediction Model for the Corrosion of Aluminium Alloy Conductors: Considering the Influence of Electric Field and Dynamic Boundary

The corrosion problems of high-voltage power transmission conductors typically occur in environments with electric fields. However, current research mainly focuses on atmospheric corrosion of metals with limited attention to the combined effects of electric fields and atmospheric conditions on metal corrosion. This study established a corrosion prediction model that considers the effects of electric fields and dynamic boundaries. Because of the influence of dynamic boundaries, this model can calculate parameters such as corrosion rate, corrosion depth, corrosion product accumulation and ion concentration for metal samples with and without an external electric field. The model is validated through indoor accelerated corrosion tests under low applied electric fields and by using aluminium alloy conductor samples from high electric field regions of actual ± 500 kV power transmission lines. The results indicate that the corrosion rate of aluminium alloys initially increases and then decreases over time. Additionally, the corrosion rate of aluminium alloys under an applied electric field is higher than that without an electric field during the same period. The mechanism of increased corrosion rate is analysed to be that the presence of the electric field accelerates the cathode reaction rate of the electrode. The corrosion rate of the sample increased by about 78% under a lower electric field (0–20 kV/m) and by about 2.75 times under a higher electric field around 2000 kV/m.