The Study Of Grounding Grid Corrosion Electrochemical Measurement Method

Grounding grid is the indispensable facilities in the electric power system to ensure the system and the people to stay safe. Operating in harsh underground environment in the long term and under a variety of corrosion, defects is very prone to occur, which will affect the stability of power system and threaten the safety of human life. And even lead to serious accidents. It may lead to huge economic losses and adverse social impact. Therefore, it is necessary to monitor the corrosion status of the grounding grid at any time, Corrosion rate measurement method of grounding grid and the evaluation method of grounding grid corrosion status are studied in this paper.For the measurement of corrosion rate, the strong polarization region extrapolation method was improved,the accuracy is better. Strong polarization region extrapolation method to calculate the corrosion rate has the advantages of simple calculation and does not depend on other parameters.The error of the method of strong polarization region extrapolation is too large which is found by comparing the results of different methods by using corresponding different regions of the polarization curves. The method is improved by analyzing the theory of polarization curve and selecting the further region from the corrosion potential as a strong polarization region. Finally, the improved strong polarization region extrapolation method is verified by comparing with the other polarization curve calculation method and weight loss method. And the improved method can accurately measure the corrosion rate of ground grid materials in the soil.For the measurement of corrosion rate sensor, the stainless steel is chose as the auxiliary electrode and the reference electrode by the contrast experiment. And the local closed limiting method is applied to the soil environment, a corrosion rate measurement sensor is designed, its measurement results is more accurate and it is applicable to the grounding grid environment. The corrosion current is the same as the standard electrode when selecting stainless steel electrode as reference electrode and auxiliary electrode. And it is better than other materials. The local closed current limiting method was applied to the soil environment, and the current limiting effect is verified by simulation and making simple device to test. It is proved that the effect of the local closed current limiting method is ideal, it can be used in soil environment.The relationship between the strong polarization attenuation curve and the corrosion degree of the grounding grid is studied by monitoring the strong polarization attenuation curve of the grounding grid material. Laying the foundation for the evaluation method of the grounding grid. Two groups of grid materials is accelerated corroded and cathodic protected separately, and the strong polarization attenuation curve is monitored for a long time. By using the superposition for average method to smooth the measured experimental data, then fitting the curve, the slope of the logarithm of voltage is obtained. It is proved that the strong polarization decay curves can reflect the corrosion degree of the grounding grid, and the slope of the logarithm of voltage increases with the deepening of the degree of corrosion.