On the role of power-grid and communication-system interdependencies on cascading failures

The mutual functional dependencies between a power grid and its supporting communication system demands that smart grids be studied as a single, electric-cyber system, especially when the reliability of the system is of concern. In this paper, we consider two functional dependencies of power grids on communication networks, namely, state estimation and transmission of critical control signals. Conversely, we consider the dependency of the communication system on the power grid for its power supply. By embedding the coupling effects in the DC power-flow optimization problem, we model the dynamics of cascading failures using successive changes in states of both systems. We show that as the level of dependencies increases severe cascading behavior is observed. Further, we show how the connectivity of the communication system affects the reliability of the power grid.