Development Of A Grounding Grid Location And Corrosion Detection Device For Power Transmission Towers Based On Electromagnetic Method

In recent years,with the planning and construction of batches of key power transmission and transformation projects,it is particularly critical to ensure the safety of equipment and personnel and meet the needs of system operation.As a common grounding protection device,the grounding grid will cause direct or indirect damage to the power system due to corrosion faults,and threaten the normal operation of the power system.Therefore,testing the corrosion status of the grounding grid has gradually been put on the agenda.However,the grounding grid is generally buried in the ground,and its corrosion status cannot be determined intuitively,so the corrosion detection method of the grounding grid has become the focus of research.Traditional grounding grid corrosion detection methods include: overall excavation;use a shaker to measure the grounding resistance,and select a point for excavation.It can be seen that the traditional detection methods are extremely blind.They consume a lot of manpower,material and financial resources,but also hinder the normal operation of the power system.New grounding grid corrosion detection methods mainly include: electrochemical method,electrical network method,electromagnetic method,all need to know the laying position and depth information of the grounding conductor.Due to the limitations of the electrochemical method and the electrical network method of detection principles and methods,this paper uses the electromagnetic method to detect the position,depth and corrosion degree of the grounding grid of the transmission tower by means of alternating-frequency alternating current excitation.In engineering practice based on electromagnetic grounding grid positioning and corrosion detection,fluxgate sensors and AMR sensors are commonly used to collect basic magnetic induction data.Although the fluxgate sensor has good robustness,it is expensive,bulky,difficult to package,and low frequency response;AMR sensor not only has good stability,low cost,easy packaging,high resolution,and high frequency response,but also low power consumption on site.Therefore,this paper uses AMR sensors to collect the magnetic field information of the tower grounding grid.The main research contents of this paper are as follows:(1)Based on the principle of electromagnetic induction to detect the location and corrosion degree of the grounding grid of the transmission tower,the influence of factors such as the ray structure of the grounding grid of the tower,soil resistivity,frequency and size of the excitation current on the distribution of the magnetic induction intensity on the surface of the ground is simulated and analyzed by CDEGS software.(2)Based on Biot-Savart's law,the formula for calculating the magnetic induction intensity of a single grounding grid is derived;a design scheme of the pole tower grounding grid positioning and corrosion detection probe based on the array type AMR sensor is proposed.The distance between sensors is calculated based on Biot-Savart law,and the rationality of the optimal distance between sensors is verified by CDEGS software simulation analysis.(3)A set of experimental platform for pole tower grounding grid positioning and corrosion detection is built for the research work of this paper.Developed the pole tower grounding grid positioning and corrosion detection probe based on the array type AMR sensor;designed the pole tower grounding grid positioning and corrosion detection mobile device,used to carry the detection probe,sensor power supply and other hardware equipment;using LabVIEW to write the pole tower grounding grid Positioning and corrosion detection on the host computer for data collection,processing and result display.(4)A method for detecting the location of the grounding grid of the transmission tower and the degree of corrosion is proposed,and the experimental platform built in this paper is used for experimental verification,which proves the effectiveness of the electromagnetic method for the location of the grounding grid of the tower and the detection of the degree of corrosion.The method in this paper is simple,reliable and accurate,and can be further applied to actual engineering conditions.