Method for Calculating the Galvanic Corrosion Rate of Copper-Steel Connected Ground Grids

During the reconstruction or expansion of power plants and substations, copper and steel ground grids are often connected, and the resulting galvanic corrosion shortens the service life of steel ground grids. However, no method is yet available for calculating the galvanic corrosion rate of the entire ground grid. On the basis of electrochemical theory, method of moments, and Taylor's formula, a method is proposed for calculating the galvanic corrosion rate of connected ground grids composed of dissimilar metals, and the effectiveness of this method is verified through galvanic corrosion experiments and FEM. For an actual project in which copper and steel ground grids are connected, the galvanic corrosion rate distribution of ground grids is calculated and analysed. According to the results, galvanic corrosion can significantly reduce the service life of ground grids, and in this engineering case, the remaining service life of the steel ground grid is reduced from 17.4 to 9.7 years (a decrease of 44.3%). The galvanic corrosion rates at the edges and corners of steel ground grid are considerably higher than those in its interior, and the galvanic corrosion rate of the steel ground electrodes is highest near the copper ground grid.