With the rapid development of electrified railways

the frequent fluctuations and mobile impacts of traction loads pose potential threats to the safety and stability of the power grid. Quantitative assessment of grid vulnerability under traction load access can provide a theoretical basis for the location of electrified railway access points. In this context

this study employs an energy function to characterize the power grid state's vulnerability

focusing on changes in potential energy induced by traction load power. To capture the structural vulnerability of the power grid caused by variations in source-load characteristics of traction loads

the concept of electrical betweenness is utilized. Additionally

information entropy is applied to both state- and structural-vulnerability metrics

and a comprehensive vulnerability index is proposed that accounts for node-level heterogeneity within the grid. Case studies demonstrate that the proposed index effectively captures variations in grid structure and state

identifies critical vulnerabilities

and provides guidance on integrating traction loads into the power grid.