Research On Grounding Characteristics Of Auxiliary Grounding Grid Considering Terrain

The long-term effectiveness of power system grounding is a prerequisite to ensure the safe and stable operation of power equipment,and it plays an extremely important role in improving the lightning resistance of transmission lines and reducing lightning accidents.Current transmission line poles and towers have problems such as high soil resistivity,difficult grounding construction,and low resistance reduction efficiency.Soil conditions and the skin effect and inductance effect of the grounding conductor under the action of high-frequency current are important factors that affect the dispersion characteristics of grounding devices.Research on the influence of these factors on the dispersion characteristics of grounding devices will improve the protection of transmission line tower grounding systems.Thunder performance is of great significance.This paper focuses on the research on the grounding characteristics of the auxiliary grounding grid of the pole tower considering the terrain characteristics.The main research contents include:(1)In view of the research on the grounding characteristics of transmission line towers in plain areas,a single-extended auxiliary grounding grid model and a multi-directional distributed auxiliary grounding grid model were established respectively,and the effects of factors such as extension leads,auxiliary terminal forms,and soil conditions on the grounding characteristics of transmission line towers were simulated and calculated.The simulation data results show that: the resistance reduction efficiency of the single-epitaxial auxiliary grounding grid increases with the increase of the extension lead length;under power frequency conditions,when the number of extension leads increases from 1 to 5,the tower auxiliary grounding grid decreases The resistance efficiency has increased by 16.52%;under the condition of uniform soil resistivity,the auxiliary grounding grid in the form of a vertical auxiliary terminal has the best resistance reduction efficiency.The extension leads of the same length are laid in equal sections and multi-directionally.As the number of sections increases,the resistance reduction effect is gradually improved.At a current frequency of 200 k Hz,compared to a unidirectional auxiliary grounding grid,the shunt coefficient of the four-way auxiliary grounding grid is higher.10%,the resistance reduction efficiency is increased by 28%.(2)Aiming at the research on the grounding characteristics of the auxiliary grounding grid of the hillside tower,a mountain micro-topography model was built to study the influence of factors such as the hillside tower’s extension lead,auxiliary terminal position,and the material of the extension grounding body on the grounding characteristics of the hillside tower.The simulation data shows that when the hillside pole tower extension auxiliary grounding grid is laid one-way,it should be laid down along the hillside,and not upside down the hillside;the extension leads of the same length and increasing the number of extension leads can have a good resistance reduction effect,at 200 k Hz Under high-frequency conditions,the resistance reduction efficiency of the four-way extension is more than 5% higher than that of the two-way lateral extension,and the shunt coefficient of the four-extended extension is 6% higher than that of the two-way extension and 3%higher than that of the two-way extension.(3)Aiming at the research on the grounding characteristics of the ridge pole and tower extension auxiliary grounding grid,the ridge pole and tower auxiliary grounding grid model is established,the influence of the extension lead,auxiliary terminal position and other factors on the ridge pole and tower grounding characteristics is studied,and the effective dispersion length of the long-distance extension grounding body is calculated.For the extensional laying direction of ridge poles and towers,it is not advisable to lay grounding grids at the ridges,and the grounding grids should be laid down the hillside;at a current frequency of 200 k Hz,the resistance reduction efficiency of four-extended laying is more than 5% higher than that of two-way left-right laying;power frequency conditions The resistance reduction efficiency of the auxiliary terminal at the foot of the mountain is about 30% higher than that of the mountain ridge,and the resistance reduction efficiency of the auxiliary terminal at the mountainside and the foot of the mountain under the current frequency of 200 k Hz is still about 12% higher than that of the ridge.The relevant conclusions of this article can provide references for reducing the grounding resistance of transmission line towers and lightning trip rate,and improving the safe and stable operation of transmission lines.