ELECTRIC POWER GRID INTERDICITION Javier Salmeron and Kevin Wood, Naval Postgraduate School Ross Baldick, University of Texas at Austin Sponsored by DoJ, Office of Domestic Preparedness

Purpose In this presentation we will... Show the importance of analyzing vulnerabilities of electric power systems to terrorist attacks Present our models, and exact and heuristic algorithms to carry out this analysis Present results on standard IEEE Reliability Test Networks

A Long-Recognized Issue (I) “One can hardly imagine a target more ideal than the U.S. domestic energy” (A.B. and L.H. Lovins, 1983) “Any U.S. region could suffer lasting and widespread blackouts if three or more substations were targeted.” (OTA, 1990) “The U.S. is at, or is fast approaching, a crisis stage with respect to reliability of transmission grids.” (NERC, 2001) “The U.S. electric power systems must clearly be made more resilient to terrorist attack.” (Committee on Science and Technology for Countering Terrorism, NRC, 2002)

A Long-Recognized Issue (II) (On Ahmed Ressam) “They were specifically trained to attack critical infrastructure, including electric power plants.” (CNN, 2002) “And the threat isn't simply academic. U.S. occupation forces in Afghanistan discovered Al Qaeda documentation about the facility that controls power distribution for the eastern U.S., fueling fears that an attack on the power grid may one day become a reality.” (Energy Pulse, 2003) “Blue Cascades” project (simulated terrorist attack on the Pacific Northwest's power grid). The study showed that such an attack, if successful, could wreak havoc on the nation's economy, shutting down power and productivity in a domino effect that would last weeks. (Energy Pulse, 2003)

Terrorist Threat Potential targets: Generating plants Transmission and distribution lines Substations Easy disruption + Widespread damage + Difficult recovery

Our Approach Assumes Information Transparency: Same information is available to both sides Uses optimization to assess worst-case disruptions Goal: To provide insight on physical vulnerabilities and protective plans that proactively hedge against disruption caused by terrorist attacks

Mathematical Analysis of the Problem In order to better defend the electric grid it is valuable to understand how to attack it! Optimal power flow model (minimizing load shedding) Interdiction model (maximize disruption) Additional features of the problem are: Time scale: Very short-, short-, medium- and long-term Customer types; ability to “share the pain” Uncertainty about terrorist resources Assumptions on protection resources

Power Flow Model (DC Approx.) DC-OPF: s.t. i: bus, l: line, g: generator, c: customer sector PLine, PGen: power (MW) S: power shed  : bus phase

Interdiction Model I-DC-OPF: Where: Etc... DC-OPF after interdiction s.t. Etc...

Heuristic Solve the DC-OPF Power Flow Model given the current grid configuration Based on the current and previous flow patterns, assign a “Value” (V) to each interdictable asset Interdict the assets that maximize “Total Value”

Exact Linearization of the Model

IEEE Reliability Test System 96-99 Total load: 2,850 MW Load shedding: 1,258 MW Load shedding: 1,373 MW Interdiction resource: 6 terrorists Line x1 Single transformer x2 Bus or substation x3 Salmeron, Wood and Baldick (2004), IEEE Transactions on Power Systems

IEEE Reliability Test System 96-99 Load: 5,700 MW 12 terrorists Shedding: 2,516 MW Salmeron, Wood and Baldick (2004), IEEE Transactions on Power Systems

Resources M (no. of terrorists) System Restoration Trafos with spares Lines MW shedding One to several days No repair Days to one week Weeks Slow repair >1 months t (Attack) 768 3 YES Substations N/A NO Generators 360 Buses 2 Transformers Lines (underground) 72 1 Lines (overhead) Outage Duration (h) Resources M (no. of terrorists) Interdictable Grid Component E.g.:

IEEE Reliability Test System 96-99 Salmeron, Wood and Baldick (2004), IEEE Transactions on Power Systems Total Load: 2,850 MW 2 t MW +72h Attack 3 +768h Substation Protected 4 +360h

Directly Interdicted Components Results for the Linearized MIP Case/Algorithm Directly Interdicted Components Time Period Power Shed (MW) Energy Shed (MWh) RTS-Two-Areas (M=12) HEURISTIC Substations: Sub-A1, Sub-A2, Sub-B1, Sub-B2 0-768 1,416 1,087,488 Total: 1,087,488 MIP Lines: A23, B23 Transformers: A7, B7 Substations: Sub-A2, Sub-B2 0-72 h 1,804 129,888 72-768 h 985,536 Total: 1,115,424 Case/Algorithm Directly Interdicted Components Time Period Power Shed (MW) Energy Shed (MWh) RTS-Two-Areas (M=24) HEURISTIC Buses: 116, 118, 215, 218 Substations: Sub-A1, Sub-A2, Sub-B1, Sub-B2 0-360 h 2,693 969,480 360-768 h 1,416 577,728 Total: 1,547,208 MIP Lines: A30, A33-2 Transformers: A7, B7 Buses: 115, 118, 215, 218 Substations: Sub-A2, Sub-B2 0-72 h 3,164 227,808 72-360 h 2,716 782,208 360-720 h Total: 1,587,744