  Network motifs are often called the building blocks of networks. Analysis of
motifs is found to be an indispensable tool for understanding local network
structure, in contrast to measures based on node degree distribution and its
functions that primarily address a global network topology. As a result,
networks that are similar in terms of global topological properties may differ
noticeably at a local level. In the context of power grids, this phenomenon of
the impact of local structure has been recently documented in fragility
analysis and power system classification. At the same time, most studies of
power system networks still tend to focus on global topological measures of
power grids, often failing to unveil hidden mechanisms behind vulnerability of
real power systems and their dynamic response to malfunctions. In this paper a
pilot study on motif-based analysis of power grid robustness under various
types of intentional attacks is presented, with the goal of shedding light on
local dynamics and vulnerability of power systems.
