Electromagnetic Environment Analysis And Lightning Protection Grounding Technology Research Of Shared Tower

Shared tower refers to the communication base station and power tower to build communication equipment on the tower.In this new mode,the electromagnetic coupling problem in power and communication is becoming more and more prominent,so it is essential to study the electromagnetic compatibility of shared towers.Based on the lightning protection and grounding project of shared tower,this paper studies the electromagnetic environment and lightning protection and grounding of shared tower.The main contents include the following aspects:(1)From the perspective of the mechanism of power equipment and communication equipment,the electromagnetic compatibility problem of shared tower mode is proposed,including the electromagnetic environment of transmission line under normal working conditions and the reliability of shared tower grounding under lightning strike.By comparing the existing modeling methods of tower and grounding grid,the electromagnetic field modeling suitable for sharing tower is selected.The shared tower model is built,including tower,transmission line,communication cable,tower grounding grid and base station grounding grid.(2)Considering the length of insulator string,power frequency voltage gap,personnel safety margin and other factors,the antenna electrical safety distance of conventional tower(35k V tangent tower,110 k V cat-head type tower,220 k Vdrum type tower)is calculated.According to the transmission line capacity,line operation mode and other factors,the power frequency electromagnetic field distribution law of the side edge of the tower is calculated.Considering the electrical safety distance and the magnetic field limit,the appropriate antenna carrying height is obtained.(3)A lightning strike sharing tower shunt model is established,and the appropriate number of towers,shunt coefficient,and transient current and potential distribution at different locations of the tower are calculated.By analyzing the influence of cable connection mode,antenna equipment installation height,grounding grid connection type,grounding body structure,tower type and other factors on lightning current distribution,lightning overvoltage distribution,transient ground potential rise(GPR)of grounding grid,and cable disturbance,a reliable grounding scheme of sharing tower is obtained.