Impact Impedance Test And Transient Electromagnetic Simulation Analysis Of Weathering Angle Steel Tower

Weathering angle steel tower is a promising new type of environmental protection transmission line tower,which not only solves the environmental treatment problem of Cr⁶⁺produced in the hot galvanizing process of ordinary galvanized steel tower,but also reduces the manpower and economic cost of line maintenance in the middle and later period of operation.Impulse impedance is an important parameter to evaluate the lightning counterattack performance of tower.After the tower falls into lightning,the tower top potential rises,which may lead to lightning counterattack flashover of tower insulator and damage of electrical equipment.In the natural environment,a dense oxidation protective layer will be formed on the surface of weathering steel material,which can not only prevent the matrix from further corrosion along the depth direction,but also increase the tower lap resistance,thus increasing the lightning transient withstand voltage of tower insulation.Therefore,the research on the impact impedance and transient electromagnetic field of weathering angle steel tower can provide valuable reference for the lightning protection design of transmission line tower made of this material.In this paper,the impact impedance field test of a 220 kV transmission line weathering angle steel tower is carried out,and the lightning transient electromagnetic field simulation of the tower is carried out based on the transmission line matrix model（TLM）.Based on the electromagnetic field theory,the influence of electromagnetic coupling between the tower and the injection line is considered.This paper compares the tower current and tower top potential under different injection line angles,and puts forward the injection line angle which is most suitable for field test under actual conditions.The field impulse impedance test scheme for weathering angle steel tower of 220kV transmission line is designed,and the test data of tower injection current and tower potential rise under different impulse voltage levels are obtained.The influence of field test environment on test results is proposed.At the same time,based on the field test device layout and test results,this paper uses the simulation method to simulate the field test,verifies the parameter setting of the simulation model,corrects the test results,and calculates that the impulse impedance,zero frequency resistance and low frequency inductance of the tower are about 53.4Ωand 31.69μL,respectively.According to the three-dimensional simulation model of the tower,the insulation withstand voltage of the weathering angle steel tower under different amplitude lightning current is calculated.