Joint Substation-Transmission Line Vulnerability Assessment Against the Smart Grid

Power grids are often run near the operational limits because of increasing electricity demand, where even small disturbances could possibly trigger major blackouts. The attacks are the potential threats to trigger large-scale cascading failures in the power grid. In particular, the attacks mean to make substations/transmission lines lose functionality by either physical sabotages or cyber attacks. Previously, the attacks were investigated from substation-only/transmission-line-only perspectives, assuming attacks can occur only on substations/transmission lines. In this paper, we introduce the joint substation-transmission line perspective, which assumes attacks can happen on substations, transmission lines, or both. The introduced perspective is a nature extension to substation-only and transmission-line-only perspectives. Such extension leads to discovering many joint substation-transmission line vulnerabilities. Furthermore, we investigate the joint substation-transmission line attack strategies. In particular, we design a new metric, the component interdependency graph (CIG), and propose the CIG-based attack strategy. In simulations, we adopt IEEE 30 bus system, IEEE 118 bus system, and Bay Area power grid as test benchmarks, and use the extended degree-based and load attack strategies as comparison schemes. Simulation results show the CIG-based attack strategy has stronger attack performance.

I. Introduction

The U.S. power grid has been developing over a century and becomes an extremely complicated system that has more than 55,000 substations and nearly 500,000 kilometers of transmission lines. Such a complex system likely experiences severe blackouts, which cause catastrophe to modern societies. For instance, Northeastern blackout of 2003 left more than 55 million people in dark for days and resulted in estimated 10 billion U.S. dollar economic loss [1], [2]. In addition, the emergence of the “Smart Grid”, the next-generation power transmission system [3], can significantly increase the risk of system failures caused by errors from computer software and hardware [4], cyber intrusions [5], [6], and so on.