Hardening the Grid: Research Team Focuses on Quake Proofing Transformer Bushings
In an earthquake, seismic waves cause the up-and-down or back-and-forth oscillating ground motion that is transferred into large power transformers. Because of their flexibility and density, big power transformer tanks made of steel and filled with insulating oil can resonate dynamically with the equipment mounted on them. When a tank and its mounted bushings are on the same wavelength, there’s a danger the amplified shaking from the earthquake will stress the bushings to catastrophic failure.
Vaagensmith and his colleagues – Chandu Bolisetti of INL and Jon Bender of WEGAI, a Boise-based engineering firm – are seeking to tackle this problem by inventing a decoupling device that shifts the resonance frequency of the bushing away from that of the transformer. The decoupler they are designing can be easily installed at the base of the bushing and retrofitted to older transformer models for a low cost. The team is pursuing a patent on the design.
Their project was initially funded through INL’s Laboratory Directed Research and Development program. It is now collaboratively supported by the U.S. Department of Energy’s Office of Electricity’s Transformer Resilience and Advanced Components (TRAC) program and the department’s Office of Cybersecurity, Energy Security and Emergency Response (CESER). The TRAC program exists to speed up grid modernization by addressing challenges in grid hardware technologies, including large power transformers. The CESER office aims to secure and strengthen U.S. energy infrastructure against threats and hazards.
At the culmination of their project, Vaagensmith and his colleagues hope to test their resonance frequency decoupler in a big way. They’ve managed to secure a 500,000-pound transformer, which they hope to take to the earthquake simulator at the University of California San Diego in 2026. The university’s shake table is the largest of its kind in the U.S. and rivaled only in size by another in Japan. This will be the first test of its size and could significantly impact safety requirements for transformers in seismic zones.
“This is a rare opportunity,” Bolisetti said. “To me, it’s miraculous.”
The Main Event
In collaboration with the University at Buffalo, the team has plenty of opportunities to get things wrong. That is the purpose of experimentation. “We can fail however we want to fail,” Vaagensmith said. “We can try out our solution and test to the limits. We want to be sure we know how to design the decoupler before we go to San Diego.”
Word in the industry is spreading, especially since the INL team gave a main stage presentation in October 2024 to the Institute of the Electric and Electronics Engineer’s Power and Energy Society Transformer Working Group Committee’s annual fall meeting, where industry standards for all things related to transformers are created. “People are excited about this,” Vaagensmith said. “We have an opportunity to resolve a longstanding debate about appropriate seismic transformer protection measures and come up with a solution for bushing manufacturers that doesn’t require them to retool. Utilities will be happy, and the grid will be more resilient. We already have people saying, ‘When are you selling tickets?’ Industry is very interested.”
Paul Menser is Communications Specialist at Idaho National Laboratory. The article was originally posted to the website of the Idaho National Laboratory.
