Study On Grounding Resistance Reduction Performance Of Super Absorbent Polymer Material

The grounding device is the important basic equipment for operation,lightning protection and safety of power system,and it is the key section to guarantee the safe and reliable operation of power equipment.However,the bad effect of dispersed lightning current in the practical project is one of current difficulties for lightning protection of transmission line in China.Under the existing conditions,choosing a grounding resistance-reducing material that is environmental-friendly,low in corrosion,good in water absorption and moisture retention,and long in service life is a new idea for ensuring the long-term stable operation of the entire power system.This article proposed the method of utilizing super absorbent polymer to modify grounding backfill soil to apply to the practical project of lightning protection and grounding for tower.The impulse current dispersion efficiency according to the soil discharge image is evaluated.The influence from different water absorbency of super absorbent polymer and using concentration in modified soil is discussed.The stability of resistance reduction of super absorbent polymer and its corrosiveness to grounding conductor is studied.The following three aspects are carried out for the detailed research work in this article:First,whether the super absorbent polymer satisfies the power frequency drop resistance requirements of the grounding system is analyzed.The corresponding experimental scheme was designed.The water absorption and conductivity of the macromolecular water-absorbing resin and the resistance-reducing effect of the modified soil were analyzed and compared through the experimental results.The mechanism of the reduction was analyzed.According to the test results,the specific resistance of super absorbent polymer after absorbing water saturation is about 0.5Ω·m,and the resistivity of the modified soil with the increase of the water absorption ratio or the application concentration of the material shows the tendency of decreasing and eventually saturating.In this paper,the simulation calculation of the reduction efficiency of the grounding resistance of super absorbent polymer to the tower grounding device is performed.The reduction rate of grounding resistance can reach 38%,and the optimal material is proposed.The dosage is 0.5%of the dry weight of the soil,and the amount of water absorbed by the material is 100 times the mass of the material itself.It can be used as a reference for applying the material to the design of grounding device.Then,the performance of super absorbent polymer under impulse current is studied.According to the soil impact discharge observation test platform,the soil discharge image was obtained.Through processing and analysis of the soil discharge image,the image parameters of the soil discharge were extracted and the area of the soil impact discharge area S₀ and soil discharge three-dimensional volume V,and the peak value of discharge impulse current per unit volume as an index to evaluate the impact resistance.When the water-absorption rate reaches saturation,multiple discharge channels appear in the soil,so that the discharge image feature of the soil is multiplied,and the smaller the value of the discharge impulse current per unit volume,the more favorable the leakage current of the impact current in the soil.The impact of lowering resistance more efficient.From the point of view of the discharge impulse current per unit volume,the performance of grounding electrode reflected by the super absorbent polymer is superior to that of bentonite natural sand.The advantage of the evaluation method of the drop resistance efficiency of the grounding resistance reducing material is obtained.This article studied the long-term effect of super absorbent polymer and the corrosiveness from material to grounding conductor.And researched the resistivity of super absorbent polymer modified soil changing with time under the natural condition,the rising rate of resistivity of soil decreased with raising of the concentration of material in the soil,when the concentration of material in the soil was over 0.5%,the resistance of soil tended to be unchanged basically within 90 days,the material has the well stability of resistance reduction.And studied the corrosion rate from material-modified soil to grounding conductor through the researching method of on-site burial,the corrosion rate from soil to metal material tended to be increasing first,then decreasing,and smooth in the end with raising of concentration in the soil.It indicated that the super absorbent polymer has the anti-corrosive property after it reaches a certain value.At last,this article integrated with the researching content said above to propose the using method and amount of super absorbent polymer that can guide the using method in project.