Research On Impact Dispersion Characteristics Of Tower Grounding Device Under Complicated Working Conditions

The impact characteristics of the tower grounding device directly affects the lightning protection effect of transmission lines.High-voltage transmission lines are located in the field,the tower grounding device operating conditions are complex and variable,complex soil structure,continuous lightning shock,etc.have a great impact on its impact dissipation characteristics,but less research on the grounding dissipation characteristics of the tower under complex working conditions.In order to optimize the design of pole tower grounding system,this paper carries out research on the impact dissipation characteristics of pole tower grounding device under complex working conditions from both experimental and simulation aspects,and the main contents are as follows.In order to study the influence of soil layered structure on the impact dissipation characteristics of grounding device,a simulation method of impact characteristics of pole tower grounding device based on ATP-Draw is proposed,a chain circuit model of grounding device distribution parameters under double-layer soil structure is established,and Laplace method is used to calculate the grounding resistance values of horizontal grounding body and vertical grounding body in double-layer soil,and then determine the conductivity parameters,capacitance parameters,inductance parameters,etc.;the test results of typical grounding devices verify the reliability of the model to calculate the impact grounding resistance.The impact grounding resistance of horizontal grounding body,vertical grounding body and three-dimensional grounding device under horizontal layered soil structure was analyzed and calculated by the simulation model.The results show that:when the soil thickness is certain,the resistivity change of the upper layer of soil has a certain influence on the impact grounding resistance of the horizontal grounding body;when the soil thickness is certain,with the increase of soil resistivity,the impact grounding resistance of the vertical grounding body changes more obviously,and the impact characteristics of the vertical grounding body are influenced by soil stratification;the impact grounding resistance of the three-dimensional grounding device decreases obviously,which indicates that the three-dimensional grounding device has a better adaptability in the horizontal There is better adaptability in layered soil,in engineering applications,the use of three-dimensional grounding device can obtain good resistance reduction effect.As a typical application case,the deficiencies of steel cylinder pile grounding under double-layered soil structure are analyzed,and the solution of adding horizontal ray-type grounding electrode is given,which provides methodological guidance for the design of steel pipe tower pole tower grounding device.The relationship between soil resistivity and inrush current change under inrush current is analyzed by soil ionization test;the ATP-Draw simulation model of pole tower grounding device under continuous lightning strike is built to simulate and study the inrush grounding resistance of grounding device under continuous lightning current impact.The effects of different continuous inrush current peaks and soil resistivity on the discharge recovery time are considered to study the cumulative effect on the grounding device,which can be used in the design of the pole tower grounding system.The authors systematically study the impact dissipation characteristics of the pole tower grounding under complex operating conditions,which is of great importance to reduce the impact grounding resistance and improve the lightning resistance of the pole tower grounding device for transmission lines.