A Derivative-Based Method for Buried Depth Detection of Metal Conductors

Buried depth of grounding grids is one of the important factors to determine the grounding performance in substations, however, the real buried depth of grounding grids is changed and unknown due to the drawing loss and backfill during the reconstruction of the grounding grids. This paper proposes a derivative-based method to detect the buried depth of different metal conductors. First, the theoretical basis for the derivative-based method to detect the buried depth is described, and an example calculation on buried depth detection according to the magnetic derivation characteristic is carried out for a single conductor case. The results indicate that the main-side-peaks characteristic of the derivative method can determine the buried depth of metal conductor effectively. Then, the analysis of grounding grids is carried out to verify its validation in grounding grid buried depth detection, and results indicate that the method is effective in the cases of magnetic field superimposing, different buried depths of grounding grid, and nonuniform distribution of current in grounding grid. Finally, the experimental results prove that the derivative method works well with low error.