Study On Lightning Protection Mechanism Of Anti-lightning Rod Based On Electromagnetic Field Theory

Lightning strike is the main reason for overhead transmission line trip-out. Scholars proposed multiple new type lightning protection device to reduce lightning trip-out accidents. Thereinto, anti-lightning rod received much attention. However, the lightning protection mechanism of anti-lightning rod still has no reasonable explanations at the stage of research results so far.Aiming at the above problems, this article carried out the research on the equivalent distributed parameter of anti-lightning rod based on finite element analysis software COMSOL Multiphysics using electromagnetic field theory, and verified its lightning protection effect based on electromagnetic transient simulation program PSCAD/EMTDC. And then, the protection mechanism was investigated with the above analyses. Firstly, the distributed parameter model of anti-lightning rod was established based on the equivalent circuit of transformer winding wave process. Furthermore, a detailed analysis and simulation of the distributed parameters and its influencing factors were developed by using the finite element analysis software COMSOL Multiphysics. Afterwards, based on the electromagnetic transient analysis software PSCAD/EMTDC, the simulation program for the lightning overvoltage and lightning withstand level of back-flash of 220 k V overhead transmission line were established, including the tower model, insulator leader propagation flashover model and the model of tower nonlinear impact resistance. Moreover, the author studied on the effect of the anti-lightning rod for the lightning withstand level of back-flash and its lightning protection mechanism with the above established simulation program. Finally, the papers discussed the effect of distributed parameters of the anti-lightning rod for the lightning current waveform and the lightning withstand level of the transmission line systematically, and put forward the optimization method of distributed parameters.The results of this papers show that, reasonable design of anti-lightning rod has a significant effect for reducing the lightning current steepness and improving the lightning withstand level of transmission line.