Reliability Analysis for the Advanced Electric Power Grid: From Cyber Control and Communication to Physical Manifestations of Failure

The advanced electric power grid is a cyber-physical system comprised of physical components such as transmission lines and generators and a network of embedded systems deployed for their cyber control. The objective of this paper is to qualitatively and quantitatively analyze the reliability of this cyber-physical system. The original contribution of the approach lies in the scope of failures analyzed, which crosses the cyber-physical boundary by investigating physical manifestations of failures in cyber control. As an example of power electronics deployed to enhance and control the operation of the grid, we study Flexible AC Transmission System (FACTS) devices, which are used to alter the flow of power on specific transmission lines. Through prudent fault injection, we enumerate the failure modes of FACTS devices, as triggered by their embedded software, and evaluate their effect on the reliability of the device and the reliability of the power grid on which they are deployed. The IEEE118 bus system is used as our case study, where the physical infrastructure is supplemented with seven FACTS devices to prevent the occurrence of four previously documented potential cascading failures.