Research on Fault Diagnosis Technology of Substation Grounding Grids using Frequency Sweep Method

At present, there are five non-destructive evaluation methods for fault diagnosis of substation grounding grids, including DL/T standard detection, resistance network node, magnetic induction intensity, electrochemical analysis and ultrasonic guided wave detection. This paper discusses the detection of the state response of the grounding grids based on the signal input and output, and puts forward the frequency sweep method, which is the frequency sweep impedance and amplitude frequency response test technology of the grounding grids. On the basis of the corresponding test system, the grounding grids were laid at the interval of 8 m × 8 m and the test was completed under three working conditions of simulated desoldering, conductor fracture and conductor corrosion defects. For the excitation current and three response voltage waveforms obtained by 4-channel high-frequency sampling, the sweep impedance and amplitude frequency response curves are analyzed. The results of correlation coefficient analysis show that the sweep voltage waveform, amplitude frequency response curve when the conductor is broken are slightly different from those when there is no defect.