Analysis of Immunity of Relay Protection Equipment Under High-Altitude Electromagnetic Pulse

A significant difference exists between high-altitude electromagnetic pulse (HEMP) and the electromagnetic interference generated by the substation. Analyzing the immunity of relay protection equipment under HEMP is significant. First, a finite element simulation model of electromagnetic field was established based on the physical structure of typical relay protection equipment. Second, changing the polarization direction and incidence angle of HEMP, simulated and analyzed the electric field distribution characteristics of relay protection equipment boards under different working conditions. Third, simulated the field strength distribution characteristics on the selected path of the board of the equipment with a heat dissipation hole on the top of the chassis. Besides, compared and analyzed the differences in the distribution of electric fields inside equipment boards under the radiated electromagnetic fields and HEMPs. Finally, the induced voltage magnitude of the vital port of the board under HEMP excitation and the susceptibility of relay protection equipment in dealing with HEMP and cable coupling interference signals were verified through the experiment. This work is of great significance for analyzing the electromagnetic compatibility characteristics of relay protection equipment under HEMPs.