  In recent years, advanced sensors, intelligent automation, communication
networks, and information technologies have been integrated into the electric
grid to enhance its performance and efficiency. Integrating these new
technologies has resulted in more interconnections and interdependencies
between the physical and cyber components of the grid. Natural disasters and
man-made perturbations have begun to threaten grid integrity more often. Urban
infrastructure networks are highly reliant on the electric grid and
consequently, the vulnerability of infrastructure networks to electric grid
outages is becoming a major global concern. In order to minimize the economic,
social, and political impacts of power system outages, the grid must be
resilient. The concept of a power system cyber-physical resilience centers
around maintaining system states at a stable level in the presence of
disturbances. Resilience is a multidimensional property of the electric grid,
it requires managing disturbances originating from physical component failures,
cyber component malfunctions, and human attacks. In the electric grid
community, there is not a clear and universally accepted definition of
cyber-physical resilience. This paper focuses on the definition of resilience
for the electric grid and reviews key concepts related to system resilience.
This paper aims to advance the field not only by adding cyber-physical
resilience concepts to power systems vocabulary, but also by proposing a new
way of thinking about grid operation with unexpected disturbances and hazards
and leveraging distributed energy resources.
