Grid protectionPredicting the impact of hackers, earthquakes -- and squirrels -- on the power grid

What would it take for an entire American city to lose power? What circumstances and failures in the electrical grid’s infrastructure would lead to a dramatic, long-term blackout? And what weak points could utility companies invest in to help prevent a catastrophic shutdown?

A three-year project at Lawrence Livermore National Laboratory (LLNL) is attempting to answer those questions using a new algorithm called “Squirrel” to model power outages and enable government agencies and utilities to automatically identify weaknesses in the power grid. Squirrel is part of a three-year Laboratory Directed Research & Development (LDRD) project aimed at determining the risk to the grid from a cyberattack, called the Quantitative Intelligent Adversary Risk Assessment (QIARA). But because Squirrel is “cause agnostic,” according to project manager Jovana Helms, it can be used with any kind of threat or hazard, including a malicious hack, earthquake or even squirrels (which often chew into electrical wires and cause outages).

“Squirrel is part of a methodology to assess the risk by identifying critical failures,” Helms said. “It solves the inverse problem: for a given consequence of interest it enumerates critical failures that can lead to that consequence. It tells you where to pay attention and how to prioritize your resources. Once you enumerate critical failures you can determine which hazards can cause it and develop mitigations that are hazard agnostic or tailored to a specific hazard.”

LLNL notes that Researchers say one of the major challenges in determining risks to the grid is the cascade effect. If one substation fails it could impact the entire grid infrastructure. Using Squirrel, in conjunction with GridDyn, an open source power grid simulator developed at LLNL that models transmission power flow, researchers analyzed what series of actions would have to happen to cause a 500-megawatt load loss on a small grid model. Surprisingly, Helms said, the simulation found 730 critical failures of consequence, including the most susceptible relays and grid components. In about half of all critical failures, one particular relay was consistently part of the enumerated failures. Such insight could be particularly crucial when resources for bolstering grid resiliency are limited, researchers said.