High-Impact, Low-Frequency Event Risk to the North American Bulk Power System

High Impact Low Frequency Event Risk North America NERC VeracityEven though the report “High-Impact, Low-Frequency Event Risk to the North American Bulk Power System” from the North American Electric Reliability Corporation (NERC) and the U.S. Department of Energy (DOE) was released in 2010, its content is still valuable in 2014 as the utility sector is well determined to strengthen its electric infrastructure against high-impact events. The NERC and DOE have given guidelines which are slowly being implemented.

All the quotes are from the report.The full report can be accessed here.

Do not miss our resources blog section to find other relevant reports from the electric utility industry: Veracity Resources Utilities ReportsDefinition

High-Impact, Low-Frequency (HILF) events are “coordinated cyber, physical […] attacks, […] nuclear weapon, and major natural disasters” such as hurricanes, earthquakes, tsunami, pandemics and geomagnetic disturbances.

Their frequency is extremely low, but they have an impact at the regional, national or international level. Power generation, transmission and distribution, as well as health, transportation and other key sectors can easily be paralyzed.

The U.S. Department of Energy and the North American Electric Reliability Corporation have made grid resiliency a priority, with a focus on large equipment, such as power transformers.

“Today, the government and industry must recommit themselves to supporting one another to enhance the protection, resiliency, and response capabilities for the North American bulk power system in the face of these rare events.”

Mitigating such risks requires balanced investments between protection of the facilities, restoration plans and resilience efforts, as well as simply raising utilities’, industry partners’ and end users’ awareness.

Common Characteristics

  • Can occur very quickly with little warning;
  • Cause widespread impact to the sector (human and/or physical);
  • Originate from external sources outside of control;
  • Limits the extent of proactive measure;
  • Operational experience is still little.


3 types of High-Impact Low-Frequency risks

  • Coordinated Attack Risk such as cyber and/or physical attack: “The specific concern with respect to these threats is the targeting of multiple key nodes on the system that, if damaged, destroyed, or interrupted in a coordinated fashion, could bring the system outside the protection provided by traditional planning and operating criteria.” Thus the NERC has developed Critical Infrastructure Protection standards.Coordinated Attack Risk Utility
  • Pandemic Risk: “The principal vulnerability with respect to a pandemic is the loss of staff critical to operating the electric power system.” The lack of qualified personnel would slow down operations and increase risks of failure. But the impact on the power supply is recognized as minor, as the resolution of this type of issues mainly relies on health authorities.
  • Geomagnetic/Electromagnetic Disturbances: caused by the solar weather, they can affect the transmission lines and large transformers. Certain areas are more affected than others. (MAP) The 1989 blackout of Hydro Québec was due to such a electromagnetic disturbance. This event led to new operational procedures for utilities whose substations are located in areas at risk.

Geomagnetic Disturbances***


The North American Electric Reliability Corporation and the U.S. Department of Energy have given guidelines to face such events:

Coordinated Attack Risk
  • Collaboration between U.S. and Canada with direct lines of communication and coordination with the electric sector.
  • Use scenario-based models for analysis, plans and procedures for restoration
  • Evaluation of the efficacy of current bulk power system planning and practices to improve the efficacy.
  • Implementation of restoration and recovery plans.
  • Increase security clearances.
  • Input from stakeholders, government and sector partners to identify areas of improvement and additional costs.
  • Improve the current spare equipment efforts for scarce/long-procurement-cycle assets, identification of inventory of critical spares.
  • Optimize the supply chain in terms of high-impact system components.
  • Develop a lexicon of cyber and physical attack risk terms to ensure clear communication
  • Encourage the development of technological and software solutions for network security tools.
Pandemic RiskPandemic Risks
  • Incorporate previous pandemic crisis (A/H1N1) into current pandemic and business continuity plans.
  • Collaboration between NERC, Federal Electric Reliability Corporation (FERC) and state regulators through the National Association of Regulatory Utility Commissioners (NARUC), and the Federal Emergency Management Agency (FEMA) and all other involved entities.
  • Improve timeliness, granularity and quality of metrics used to measure and report on the emergence and spread of pandemic vectors.
  • Give U.S. and Canada health, transportation and utility services employees from critical sectors priority to access vaccines and travel.
Geomagnetic Disturbances, High Altitude Electromagnetic Pulse Events, Intentional Electromagnetic Interference ThreatsGeomagnetic Risks
  • Assess electromagnetic threats and initiate restoration plans.
  • Support industry efforts.
  • Design a road map for long-term research.



This report brings up the following questions:

  • How much risk is the private sector willing to accept?
  • How much risk is the public sector willing to accept?
  • How much are consumers (or society at large) willing to pay to reduce this risk?
  • Who makes the determination for society’s tolerance for risk and the cost of employing protections?
  • How should the costs of employing protections be paid for?
  • How is damage measured: cost to replace damaged equipment, number of people-hours without power, number of other critical infrastructure nodes affected?
  • Where are interdependencies most critical?


Go further

The following blog posts can help you learn more about critical equipment and grid resilience:

Equipment Criticality

Transformers: An Essential Link of the Electrical Grid

The Transformer Problem

Key points from “Economic Benefits of Increasing Electric Grid Resilience to Weather Outages”

9 Key Facts from the “Large Power Transformers and the U.S. Electric Grid” Study

Critical Spares Infographic

Your Veracity Connect Newsletter – Volume 6


Learn more about our Critical Spares Management Solution for Utilities: Veracity Connect, collaborative platformMake electrical equipment procurement easy and efficient. Locate a matching power transformer before a failure occurs, maximize your mutual aid efforts!

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