High altitude electromagnetic pulse (HEMP)

as a steep slope and high amplitude instantaneous energy shock

has stronger coupling and greater destructive power

which can easily cause the secondary control device of the substation to malfunction. In order to explore the anti-interference ability of the relay protection device to HEMP

a simulation model of electromagnetic radiation based on the actual physical structure was built

and the distribution characteristics of the electric field inside the device were explored under the influence of different excitation factors such as HEMP amplitude

incident angle

and polarisation direction. A radiation and conduction coupling test platform was built between the device and HEMP

and the HEMP threshold of the device malfunctioning due to radiated coupling interference was obtained by comparing the changes in the action characteristics of the device facing the same fault before and after irradiation. The tolerance of the device’s power port under HEMP-conducted interference is verified. The test results show that when the peak irradiation of HEMP reaches 35 kV/m

the device begins to malfunction

and the tripping time in the face of the same fault is significantly prolonged. The operational reliability of relay protection devices is greatly reduced

which affects the safe and stable operation of the power grid.