We describe VEGA, a system for analyzing the vulnerability of an electric power grid to physical attacks by terrorists, and for planning mitigation efforts. VEGA (Vulnerability of Electric Grids Analyzer) consists of a bilevel optimization model and solution algorithm, a graphical user interface and a database. The optimization model implements a Stackelberg game in which (a) a group of terrorists attacks components of a power grid ("the system") so as to maximize the amount of load that must be shed (demand for power that goes unmet), and (b) the system operator minimizes that maximum by controlling the degraded system as best possible. We illustrate the basic model using realistic data and show how it can guide a system-upgrade plan to reduce vulnerability.

Actually, we at NPS are using similar techniques to study the vulnerability to attack of a variety of infrastructure systems. This talk will discuss the common approach, and provide two examples: (a) Finding "weak spots" in the Saudi Arabian crude-oil pipeline system and (b) protecting the Washington, DC subway system from a chemical or biological attack.

Dr. Kevin Wood is professor of operations research at the Naval Postgraduate School. At NPS since 1982, he has taught courses in networks and optimization and has published research on network reliability, mathematical programming and its applications, and on interdiction. His 1993 paper "Deterministic Network Interdiction" spurred renewed interest in applying analytical techniques to network and system interdiction, and has led to a series of papers on these topics, by him and by others. He is currently applying the methodology to critical infrastructure protection in general, and electric power grids in particular: Professor Wood has long-term research support from the Office of Naval Research as well as the Air Force of Scientific Research, and has been a visiting professor at Stanford University, the National Security Agency and the University of Auckland.