  The integration of synchronous generators and energy storage systems operated
through communication networks introduces new challenges and vulnerabilities to
the electric grid, where cyber attacks can corrupt sensor measurements or
control inputs and interrupt functions such as frequency regulation. This paper
proposes a defense methodology for the design of resilient operating
constraints imposed on each generation and storage unit in order to prevent any
attack sequence from driving the system's frequency to unsafe conditions. The
resilient operating constraints are found by using ellipsoidal approximations
of the reachable set of the power system, leading to a convex optimization
problem with linear matrix inequalities. Numerical results in a single-area
power system with synchronous generation and energy storage demonstrate how the
resilient constraints provide security guarantees against any type of attack
affecting frequency measurements or controller setpoints.
