Imaging the Topology of Grounding Grids Based on Wavelet Edge Detection.

A wavelet edge detection method is introduced to image the topology of grounding grids and locate the grounding conductors from measured magnetic induction. Theoretical analysis of the magnetic field and calculation method of discrete wavelet transform are described. Since the sharpest variation of the magnetic field perpendicular to the ground surface occurs right above a conductor, the gradient vector modulus maximum of the vertical component can be calculated to extract the position information about the conductor. This scheme is derived from the Canny edge detection. A 2-D discrete à trous algorithm is used to perform equivalent edge detection as the wavelet transform avoids partial derivative. The method is robust to noise and would extract more stable and distinct edge. Extensive simulation and experimental examples demonstrate that the proposed method can accurately draw the topology of grounding grids and locate the conductors. [ABSTRACT FROM AUTHOR]