Optimized corrosion diagnosis of large-scale grounding grid

This paper presents a comprehensive optimization method for the diagnosis of large substation steel grounding grid integrity status, and the detection and location of any corrosion spot before digging out the grounding grid. A grounding grid is modeled as a circuit network, and fault diagnosis equations are derived by applying Tellegen´s theorem, optimization theory and fault diagnosis theory for analog circuit. The solution of these equations pinpoints the corrosion locations of the grounding grid. In addition, some guidelines are suggested for minimizing required number of measurements for large-scale grounding grid corrosion diagnosis. The proposed method is applied to several major substations successfully and the field test results are reported.