Vulnerability analysis in power systems is a key issue in modern society and many efforts have
contributed to the analysis. Recently, complex network metrics applied to assess the topological vulnerability
of networked systems have been used in power systems, such as betweenness metric, since transmission of
power systems is in basis of a network structure. However, a pure topological approach fails to capture
the specificity of power systems. This paper redefines, starting from the concept of complex networks, an
electrical betweenness metric which considers several of specific features of power systems such as power
transfer distribution and line flow limits. The electrical betweenness is compared with the conventional
betweenness in IEEE-300 bus network according to the unserved energy after network is attacked. The results show that the tested network is more vulnerable when the components of the network are attacked according to their criticalities ranked by electrical betweenness.