Design Of Ground Grid Corrosion Diagnosis System Based On Ultrasonic Guided Wave

The domestic substation grounding grid mainly uses ordinary flat steel as the conductor material,and its corrosion resistance is not strong,especially in China’s relatively humid environment,which is prone to corrosion,leading to a decline in grounding performance and affecting the safe and stable operation of the substation.It is of great practical significance to carry out corrosion detection.The current corrosion detection methods of grounding grids,such as high-current analysis,node analysis,electrochemical analysis,and electromagnetic imaging methods,cannot completely solve the corrosion detection problem of the entire grounding network,especially for the grounding network conductors connected to power equipment.Detection.Based on ultrasonic guided wave non-destructive testing technology,this paper researches and designs the ground grid corrosion diagnosis system,and mainly completes the following tasks:(1)By studying the propagation characteristics,dispersion characteristics,wave structure characteristics,and energy density of the Lamb wave in flat steel,the theoretical analysis shows that the A0 mode of the Lamb wave in flat steel is suitable for corrosion diagnosis of grounding network conductors.(2)Hardware design of ground grid corrosion diagnosis system.The hardware part of the grounding network corrosion diagnosis system mainly includes seismic source excitation circuit,DC voltage source,sensor modulation circuit,signal amplification module,AD acquisition module,embedded control module,embedded human-machine interface,signal filtering,etc.When designing each hardware part of the system,consider the issue of noise and battery interference,conduct circuit simulation and low-noise design for the key hardware modules of the system,and consider the signal integrity analysis for the digital part.(3)Software design of ground grid corrosion diagnosis system.The frequency band of the ultrasonic guided wave reflection echo signal received by the ground network corrosion diagnosis system is relatively wide,and spectrum analysis,filter processing,and Hilbert transform are required for data analysis.The design of the control interface is carried out through the graphic visualization tool GUI of MATLAB,and operations such as spectrum analysis,filtering processing,and Hilbert transform are packaged in the MATLAB / GUI control interface,which is convenient for system analysis.(4)Experimental research on grounding conductors.Using the grounding grid corrosion diagnosis system to carry out the experimental research on the corrosion diagnosis of single flat steel and the corrosion diagnosis of T-shaped flat steel.The experimental results show that the detection of the corrosion position of the flat steel and the position of the welding point by this system can lead to more accurate corrosion For positioning,the relative error can basically be controlled within 5%;this system can realize the detection of the corrosion degree of different sections of flat steel.