  We study the interaction between the power grid and the communication network
used for its control. We design a centralized emergency control scheme under
both full and partial communication support, to improve the performance of the
power grid. We use our emergency control scheme to model the impact of
communication loss on the grid. We show that unlike previous models used in the
literature, the loss of communication does not necessarily lead to the failure
of the correspondent power nodes; i.e. the "point-wise" failure model is not
appropriate. In addition, we show that the impact of communication loss is a
function of several parameters such as the size and structure of the power and
communication failure, as well as the operating mode of power nodes
disconnected from the communication network. Our model can be used to design
the dependency between the power grid and the communication network used for
its control, so as to maximize the benefit in terms of intelligent control,
while minimizing the risks due to loss of communication.
