Large power transformers (LPTs) are critical to the nation’s power grid, with more than 90 percent of consumed power passing through high-voltage transformers at some point. LPTs, however, face a number of challenges that make them one of the most vulnerable components on the grid. They are expensive, difficult to transport, and typically custom-made with procurement lead times of one year or longer. Many of the LPTs currently used are beyond their peak age. In addition, LPTs could be affected by natural and man-made threats facing the nation’s grid, including severe weather, space weather, and attacks. The loss of critical LPTs could disrupt electricity services over a large area of the country. With the nation’s security and economy dependent on the reliable delivery of electricity, the impact of extended outages from the loss of one or more LPTs is a significant concern. 

Over the years, OE has worked with private and public partners to increase awareness and address domestic production and transportation issues through outreach and technical assistance. Concerns about limited domestic production following events such as geomagnetic disturbances (GMDs) and electromagnetic pulses (EMPs) were discussed at the 2009 High-Impact Low-Frequency (HILF) Risk Workshop and in the resulting report. OE’s “Large Power Transformers and the U.S. Electric Grid” report, originally released in 2012 and updated in 2014, also examines a number of issues related to LPTs, including the characteristics and procurement of LPTs, historical trends and future demands, and risks facing LPTs.

Building on continued engagement with industry stakeholders, OE developed a space weather strategy to address concerns about the broader impact of extreme GMD events on transformers and the reliability of the grid.  OE’s GMD program has analyzed the impacts of a benchmark 100-year GMD event, examined the susceptibility of transformers to GMD events, and deployed sensors to measure geomagnetically-induced currents (GICs) and to enhance system modeling efforts. These efforts helped OE contribute to the development of the National Space Weather Strategy and accompanying Action Plan released by the White House Office of Science and Technology Policy (OSTP) in 2015. OE continues to work with OSTP and other federal agencies and is currently developing requirements and a plan to provide a system-wide real-time view of GICs at the regional level.

OE has also been examining the risk of EMPs and investigating how to mitigate their effects on transformers and the reliability of the grid.  In early 2016, OE and the Electric Power Research Institute (EPRI) developed a Joint Electromagnetic Pulse (EMP) Resilience Strategy for the grid and are now collaborating to develop action plans to implement this strategy. In addition, several EMP studies are currently underway at DOE’s national laboratories.  

In light of these threats, increasingly powerful storms, and potential terrorist attacks, DOE’s 2015 Quadrennial Energy Review recommended that “DOE should lead—in coordination with DHS and other Federal agencies, states, and industry—an initiative to mitigate the risks associated with the loss of transformers. Approaches for mitigating this risk should include the development of one or more transformer reserves through a staged process." In response, OE issued a Request for Information in July, 2015, asking for comments on the possible establishment of a reserve of LPTs that would support recovery of the nation’s bulk power system.

The Fixing America’s Surface Transportation (FAST) Act of 2015 requires DOE to submit a plan to Congress evaluating the feasibility of establishing a Strategic Transformer Reserve for the storage, in strategically-located facilities, of spare equipment in sufficient numbers to temporarily replace critically damaged LPTs.  In January 2016, OE assigned the technical component of this important analysis to a team led by the Oak Ridge National Laboratory. The project team included researchers from the University of Tennessee-Knoxville, Sandia National Laboratory, EPRI, and Dominion Virginia Power. The Strategic Transformer Reserve Report to Congress is available HERE.

In addition to outreach, monitoring, technical assistance, and analysis, OE also supports the research and development of innovative solutions. For example, OE and industry encouraged the Department of Homeland Security (DHS) to fund the development of a recovery transformer concept that would accelerate the time needed to replace a damaged LPT. DHS completed the Recovery Transformer (RecX) project, in collaboration with EPRI, ABB, CenterPoint Energy and DOE, in March 2013. The project included one year of field testing.

Other ongoing research includes efforts by OE’s Transformer Resilience and Advanced Components (TRAC) Program. The TRAC program portfolio spans modeling, testing, and component development to advance the capabilities of transformers and other critical grid components to enable a more resilient future grid. A Funding Opportunity Announcement on “Next Generation Transformers – Flexible Designs” released in June, 2016 focused on new design concepts that promote greater standardization to increase the ability to share LPTs in the event of the loss of one or more transformers. On September 28, 2016, funding of more than $1.5 million in new funding to allow corporations, small businesses, and academic institutions in Georgia, Illinois, New York and North Carolina to create new designs that will help produce the next generation of LPTs was announced.

In addition, through the GMLC, a team led by Oak Ridge National Laboratory (ORNL) and Lawrence Livermore National Laboratory has been selected to conduct modeling and testing of transformers to improve the understanding of vulnerabilities to the effects of GMD and EMP events. Validated models can be used to improve LPT designs and manufacturing requirements. Another team led by Pacific Northwest National Laboratory and ORNL has been selected to develop and evaluate new control strategies for High Voltage Direct Current (HVDC) systems to reduce congestion and loop flows, and provide synthetic inertia. The capabilities developed through this project have the potential to be applied to alter system power flows during emergencies to minimize the criticality of substations and associated LPTs.

As we continue to address this important aspect of helping to ensure the reliability and resiliency of the nation’s grid through these various activities, ongoing collaboration with utilities, academia, equipment vendors, regulators, and other stakeholders is vital.