HENDERSONVILLE, Tenn. (July 29, 2022)—Two Generator Step-up Unit Transformers were delivered to the Old Hickory Power Plant in Hendersonville, Tennessee the week of June 20.
The transformers were built in Lenz, Austria by Siemens Automation Company. The shipping of the transformers to the United States took two months.
With the help of a Highway Patrol escort, a transportation crew, made the slow-moving, traffic-controlled, 6.26-mile transport from south Nashville railyard to the Williams Siding at Old Hickory Power Plant. The trip took approximately 5 hours.
The GSU transformers took two days to off-loaded and contractors worked later hours than usual to install the units. Transport and installation took four days in total.
Contractors used the “jack and slide” method to offload and install the massive GSU transformers. The replacement of the GSU transformers will be completed in two phases.
The first phase consists of the GSU transformer supply phase which was completed in June with the delivery of the GSU transformers.
According to Jaser, the scope of phase one was to design, manufacture, test, and deliver the transformers.
Phase two is the installation of the transformers, which is scheduled to start in March of 2023. The transformers have been delivered and are being kept in a temporary location.
“The goal is to ensure that all the components in the power transmission system, such as the GSU transformers and the generator excitation system, are capable of producing power at maximum efficiency and able to support the uprated Old Hickory Power Plant generators once the Major Unit Rehabilitation Project is complete,” said Sam Jaser, senior electrical engineer and project manager.
The current GSU Transforms are the original ones commissioned in the 1950s. This project will be the first replacement of the transformers since the Old Hickory Power Plant was completed.
“The new transformers have subsystems, including a monitoring system and protection system, that are newer technologies having stricter specifications which contribute to maximized reliability and efficiency,” said Jaser.
Faced with several different challenges, Old Hickory engineers were still able to work around COVID delays and maintain deadlines with the Austrian manufacturer, coordinating delivery of the GSU transformers to the United States.
“Even though the pandemic was at its peak, we have an excellent team tasked to execute the mission and we were able to deliver the transformers successfully without affecting the critical time frame. It was an example of great teamwork during very challenging times,” said Mechanical Engineer Miguel Verdecchia.
Generator step-up transformers are the critical link between the power station and the transmission network, sometimes operating day and night at full load. They must be built to withstand extreme thermal loading without aging prematurely.
The replacement of the GSU transformers is one of multiple preparatory projects ahead of the Major Unit Rehabilitation Project at Old Hickory.
The ongoing Section 212 Hydroelectric Rehabilitation Program entails an upgrade to Old Hickory Power Plant’s systems and will maximize the power output of the plant. Future projects include the generator excitation system replacement and major turbine and generator rehabilitation expected to take place over the next few years.
(The public can obtain news, updates and information from the U.S. Army Corps of Engineers Nashville District on the district’s website at www.lrn.usace.army.mil, on Facebook at http://www.facebook.com/nashvillecorps and on Twitter at http://www.twitter.com/nashvillecorps.)