A Lightning Current Measurement Method Based on Optical Sensing Technology

Precise and reliable measurement of lightning current parameters is important for supplying accurate original data for the lightning protection design. Thus far, studies have focused solely on methods involving only one measurement function and the measuring devices have defects in their measurement principle when applied to the full waveform measurement of lightning current. This paper proposes a lightning current measurement method that uses optical current sensing, which has no magnetic saturation or bandwidth limitation, to directly measure the current from a lightning strike transmission tower top, indirectly measure the current from lightning in transmission lines, and identify the type of fault caused by a lightning strike. Furthermore, in this paper, a magnetic field model of a transmission tower was established by finite element simulation to analyze the magnetic field characteristics of lightning in a tower. It was found that the magnetic field waveforms obtained from the sensors in the power system are largely similar to the lightning current waveforms, and the magnetic field amplitude exhibits a stable linear relationship with the lightning current, which verified the feasibility of our optical current sensing technology applied in lightning measurement. We also performed a comparative analysis of the magnetic field characteristics when a lightning strike at the tower-top/line leads to flashover and when it does not.