The Electric Power Research Institute (EPRI) on April 30 released findings from its three-year study of potential impacts of high-altitude electromagnetic pulses (EMP) on the electric transmission system, along with options to mitigate those impacts.
An EMP event can be caused by a nuclear explosion above Earth’s atmosphere that propels electromagnetic energy towards the surface, generating an initial, short-duration pulse (E1); an intermediate pulse with characteristics similar to those caused by nearby lightning strikes (E2); followed by a late pulse (E3), which is similar to a severe geomagnetic disturbance caused by solar flares.
In January 2016, several member companies asked EPRI to engage in research to address the holistic impact of EMP on the electric transmission grid. In April of that year, EPRI and the U.S. Department of Energy agreed on a strategy to address knowledge gaps regarding the potential impact of and ways to minimize any potential damage to the electric grid from an EMP attack.
Report includes results from extensive laboratory testing and analysis
EPRI said that the report includes results from extensive laboratory testing and analysis of potential EMP impacts on the electric transmission system, with updated information that uses scenarios provided by Los Alamos National Laboratory.
EPRI also said that its research included extensive testing at its EMP laboratories in Charlotte, N.C. and Knoxville, Tenn.
The research sought to answer two key research questions. One, what are the potential impacts of a high-altitude electromagnetic pulse (HEMP) attack on the modern electric transmission system and, two, if impacts are of significant concern, what are possible mitigation options and potential costs and benefits of each?
The research specifically focused on the electric transmission system (overhead transmission lines, substations, and switchyards), and did not consider the potential effects of HEMP on generation facilities, nuclear reactors, distribution systems, loads, or other key elements or infrastructure sectors.
In order to address the two research questions that were identified, the project was broken up into five research areas: (1) environment and modeling; (2) testing; (3) assessment; (4) mitigation, hardening and recovery; and (5) decision support.
Key findings
EPRI said that key findings for the initial pulse include:
- Transmission electronic equipment damage or disruption can result from induced voltage surges in connecting cables, as well as by direct exposure to the initial pulse;
- Digital protective relays, which are devices that help detect faults in the electric system, were generally resilient to direct exposure to the initial pulse but were found to be vulnerable to the surges induced on control and communication cables.
The research indicated that initial pulse impacts could be mitigated through various options including shielded cables with proper grounding, low-voltage surge protection devices and/or filters, use of fiber optics-based communications, enhanced electromagnetic shielding of electric substation control houses and grounding and bonding enhancements.
The research also showed that the combined effects of the initial and late pulses could trigger a regional service interruption but would not trigger a nationwide grid failure. Recovery times are expected to be similar to those resulting from large-scale power interruptions caused by other events provided that mitigations specific to the initial pulse are deployed. Possible damage to large power transformers was found to be minimal.
For an intermediate pulse, the system impacts are minimal, if any, and the study found no further mitigation options are recommended.
EPRI cites significant collaboration
EPRI said that the report is its most significant collaborative research in this area to date, with funding and active support from more than 60 U.S. utilities, and collaboration with the Defense Threat Reduction Agency, the U.S. Department of Energy (including the three nuclear weapons laboratories), and the Electricity Subsector Coordinating Council (ESCC), which provides national coordination of government and utility preparation and response to disasters affecting the power system.
EPRI noted that it is working with utilities to further evaluate mitigation options for the initial pulse, including additional testing to more fully understand performance and reliability. The field assessments also can provide more information on the costs of upgrades and the installation process for installing transmission system mitigation options. EPRI will be expanding the application of its research results to power generation, it said.
“EPRI’s research represents the largest utility collaborative on this issue focused on understanding the technical facts using both laboratory testing and advanced modeling.” said Michael Howard, president and CEO of EPRI.
“The results also provide a cost-effective pathway to enhance the resilience of the grid and accelerate recovery,” Howard said. “EPRI’s research continues to support the very high priority that the electric utility industry places on providing reliable electricity for all customers.”
“EPRI’s EMP research project is very significant to everyone responsible for critical infrastructure because of the scope of the evaluation and results, the broad collaboration of support from the electric utility industry and our government partners, and the next phase to deploy pilot mitigation in the field to determine actual costs and challenges of implementation,” said Kevin Wailes, CEO of the Lincoln Electric System in Nebraska and co-chair of the ESCC.
“This information will provide the basis for ongoing development of cost effective mitigation solutions and expanding the application to other critical facilities, such as power generation,” Wailes said.
Wailes discussed possible EMP attack at Senate hearing
The U.S. electric utility industry "takes very seriously" the threat posed by the possibility of an attack using high-altitude EMP, Wailes told a Senate hearing in 2017. Wailes said at the hearing that a risk management approach is needed to counter this threat because "We cannot protect all assets from all threats."
