Radiated and conducted research on damage characteristics of digital protective relays in substations under high-altitude electromagnetic pulse environment.

This paper presents the damage characteristics of digital protective relays (DPR) in substations under high-altitude electromagnetic pulse (HEMP) environments through radiated and conducted tests. Three representative substation circuits of DPR are selected, and the radiated and conducted experiments are performed. Through a comprehensive analysis of the radiated and conducted test results, the damage characteristics of DPRs under the HEMP environment are determined, including port coupling characteristics and vulnerability, respectively. The results can be summarized as follows: the current acquisition port and the power supply port demonstrate excellent surge protection capabilities, effectively suppressing both the peak and width of the surge voltage, which endure the maximum radiated field intensity level and injection voltage level without suffering damage. In contrast, the gas protection port of the gas protection circuit lacks the capability to suppress surge voltage peaks, resulting in a higher probability of port damage and experiencing unrecoverable damage at a radiated field intensity level of 50 kV/m and injection voltage levels of 20 and 30 kV. Overall, the results of radiated and conducted experiments provide references for DPR equipment protection and comprehensive substation protection.