Extra-high voltage (EHV) transformers are critical components in the national grid because more than 90% of all power passes through them. They are also vulnerable to sustained outages due to their locations in remote substations. The transformers can weigh hundreds of tons and are often too large to transport by road. This makes them difficult to replace, often taking up to two months to deploy and energize, if a spare is available.
The U.S. Department of Homeland Security’s (DHS) Science and Technology Directorate (S&T) announced the successful completion of a test to move, deploy, and energize a trio of smaller fast-recovery transformers. These would serve as prototypes for the utility industry in an effort to significantly reduce recovery time associated with transformer-related outages.
The drill began on March 12 at a transformer manufacturing plant in St. Louis. The smaller and more easily transportable units were disassembled and loaded onto lowboy flatbed trucks for an 800-mile trip to a substation near Houston. The units were off-loaded, re-assembled, and fitted with cooling systems, conservers, and bushings and then connected to the grid. By March 17 the units were fully energized and functional, reducing the anticipated recovery time by about 75%.
“The probability of a long-term outage is relatively low, but the potential impact is significant, making this an important issue for both the public and private sector to address,” said Sarah Mahmood, DHS S&T program manager in the agency’s Infrastructure Protection and Disaster Management Division. “Through this project, DHS S&T was able to partner with the private sector to develop a solution before experiencing a problem.” In May, a year-long operational evaluation of the prototype recovery transformers was announced that could provide enhanced recovery capabilities from transformer-related outages.
The recovery transformer project team – consisting of DHS S&T, the Electric Power Research Institute (EPRI), transformer manufacturer ABB Inc. (www.abb.com), and CenterPoint Energy – developed the extra-high voltage transformers that could be deployed and energized in days instead of several weeks. DHS S&T managed this project with EPRI as the principal contractor.
“The successful completion of the drill represents a quantum leap for the electric industry to rapidly replace extra-high-voltage transformers in emergency situations,” said Rich Lordan, an EPRI technical executive and recovery transformer project manager. “This demonstrates a way forward for the industry to reduce restoration time in the event of simultaneous failure of multiple transformers.”
In 2007, the energy sector cited the need for emergency EHV transformers as high priority, based on findings from EPRI’s infrastructure initiative in response to 9/11. In 2008, DHS partnered with EPRI and the utility industry to sponsor the recovery transformer project.
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