Research on Lightning Withstand Level of 110kV Transmission Line Installed Current Limiting Coil

Because of the high cost and limitations of the traditional lightning protection methods, this paper proposes a new method to improve the lightning withstand level of 110kV transmission lines by installing current limiting coil between the tower cross arm and lightning rod. In order to verify the feasibility, this paper established the finite element model of current limiting coil to calculate the distribution parameter accurately. Then the EMTP model of lightning striking 110kV transmission lines is set up to study the effect of coil inductor on the lightning protection. The results show that the appropriate value of current limiting inductance is 0.1mH. After the installation of the 0.1mH current limiting coil, the tower current falls by 19.9%, the lightning withstand level increases by 11.8%. Finally, this paper puts forward the optimization design scheme of the current limiting coil, and checks the thermal stability and insulation level of the coil when 55kA lightning current flowing through the coil, the result of electric field strength simulation show that the feasibility of the device in the 110kV transmission lines lighting protection is remain to be verification by experiment.