Vulnerability Modelling and Status Assessment Method for Key Equipment in Substations under HEMP E1 Impact

High-altitude Electromagnetic Pulse (HEMP) poses a significant threat to substation equipment, especially with the increasing deployment of intelligent electronic device (IED). Due to the complex wiring, wide-area distribution, and high automation of modern substations, vulnerability assessments of system components are limited and incomplete. This study focuses on E1 effects, which can penetrate electronic devices, damaging sensitive internal components. By using the generalized extreme value (GEV) distribution and analyzing failure modes of critical secondary equipment, a probabilistic model to estimate the likelihood of equipment transitioning into failure states is developed, highlighting the risks of abnormal and failure states. This work addresses gaps in the current vulnerability assessment framework, leveraging existing experimental results and state transfer models, providing a basis for more comprehensive strategies and damage assessment for substations under electromagnetic threats.