Firstly, briefly explain the grounding characteristics of the new grounding material; Then, the finite element calculation method is used to compare and analyze the electromagnetic characteristics (skin effect and inductance effect) of the new grounding material with common copper and steel grounding materials; Subsequently, based on numerical calculation results, structural improvements were made to flexible graphite composite grounding materials, and expanded diameter graphite composite grounding materials were prepared. The feasibility of using graphite composite grounding materials in the grounding of transmission line towers was analyzed; Finally, the reliability of the flexible graphite composite grounding material described in this article was verified through on-site testing data of the new grounding material in the grounding projects of 110kV and 220kV transmission line towers. The research content has practical application value for anti-corrosion engineering in the field of power system grounding. Below, the editor in charge of graphite grounding will lead you to a detailed understanding.

With the continuous development of the power system, lightning strikes and tripping accidents on transmission lines are also increasing. According to the classification statistics of power grid faults, in areas with high tripping rates in China, the number of accidents caused by lightning strikes accounts for about 60% of the total tripping times of high-voltage transmission lines. Over the years, various countries have conducted extensive research on improving the lightning protection level of transmission lines, proposing various measures such as using unbalanced insulation, installing coupled ground wires, reducing line protection angles, lowering the grounding resistance of tower grounding grids, and installing lightning arresters.

Graphite grounding reminds everyone that the actual lightning protection effect of operating lines shows that a low resistance grounding grid is an important reference indicator for improving the lightning resistance level of transmission lines. Reducing the grounding resistance of grounding towers is the most economical and effective lightning protection improvement measure [3,4]. Years of experience in operating transmission lines have also led researchers to reach a consensus on this point.

At present, the grounding grid of transmission line towers still mostly uses corrosion-resistant metal materials such as flat iron, round steel, galvanized steel, etc., which face the long-term impact of metal corrosion. Especially in soil with acidic, alkaline, high salt content, and high water content, it usually takes 5-7 years to renovate or even replace the tower grounding network, which greatly increases the overall life cycle cost [5,6]. In addition, the grounding grid of transmission line towers faces problems such as high construction difficulty, low soil adhesion, and easy theft and damage during use [6,7].

In recent years, the editor of graphite grounding has learned that copper coated steel has begun to be applied in the grounding grid of transmission lines and has a certain anti-corrosion effect. However, when there are gaps or damages in the copper coating, it will accelerate the corrosion of the steel to a certain extent [8]. At present, researchers have conducted extensive research on the impact grounding characteristics, numerical calculation models, resistance reduction methods, and breakpoint diagnosis of grounding grids. However, there is relatively little discussion on how to solve the practical problems of existing grounding grids from a material perspective [9,10]. Developing new grounding materials has practical engineering significance for the renovation of transmission line grounding grids.

This article starts from the problems of corrosion, transportation and construction difficulties, low adhesion with soil, easy theft and frequent human damage in current metal grounding materials, and designs and prepares a new type of grounding material - flexible graphite composite grounding material.

Discuss the structural characteristics and basic material parameters of new grounding materials, compare and analyze the inductance effect, skin effect and other grounding characteristics of graphite composite grounding materials with copper and steel materials, and based on this, improve the structure of grounding materials. Combined with actual grounding engineering applications, explain the practical application value of the new grounding materials described in this article.

The editor of graphite grounding learned that this article analyzes the graphite composite grounding material and its grounding characteristics, and mainly draws the following conclusions.

1) As a new type of non-metallic grounding material, graphite composite grounding material has the characteristics of corrosion resistance, low cost, easy transportation and construction, close adhesion with soil, and theft prevention compared to current metal grounding materials.

2) Compared to metal grounding materials, graphite composite grounding materials have less skin effect, higher material utilization rate, and lower inductance effect than steel grounding materials. This makes the power frequency grounding resistance of graphite composite grounding materials slightly lower than that of steel grounding materials (the difference is small when the soil resistivity is above 100W · m), but the impulse grounding impedance under high-frequency lightning current is lower than that of steel.

3) Expanded diameter graphite composite grounding material was prepared by structural improvement of graphite composite grounding material. Choosing a diameter expansion rate of 30% to 40% can effectively reduce the skin effect and inductance effect of the grounding body, and expanding the diameter of the grounding body can further reduce the grounding resistance.

4) The editor of graphite grounding reminds everyone that graphite composite grounding materials meet the application requirements of transmission line tower grounding engineering under harsh geological conditions, and have practical application value and prospects.