North Carolina State University, in collaboration with the New York Power Authority (NYPA) and EPRI, has designed and tested a high-efficiency solid state transformer (SST) capable of handling up to 1 MW of power under real-world conditions. Supported by NYPA and demonstrated at EPRI’s laboratory in Lenox, Mass., the system underscores the technology’s potential to improve energy efficiency, including at installations with significant power demand such as data centers, and to provide potential cost savings in grid operations. The SST can reduce heat loss associated with power production and due to its compact size can be used in areas with space constraints.
“This is the first independently verified, megawatt-class solid state transformer validated on a live utility distribution feeder,” says Srdjan Lukic, principal investigator on the SST project and Lampe Distinguished Professor of Electrical and Computer Engineering at NC State. “This is a significant step in advancing power transformer technology.”
The SST prototype was designed, constructed, tested and deployed by NC State students and faculty. The prototype used in this NYPA-supported, EPRI-supervised demonstration was connected to a real distribution feeder at EPRI’s power delivery laboratory.
Electricity is transmitted across power lines in the form of a high-voltage alternating current (AC). However, applications that require large loads, such as data centers and electric vehicles, make use of lower-voltage direct current (DC). Conventional power systems use two pieces of technology – a transformer and a rectifier – to convert high-voltage AC into low-voltage DC. These two together- the conventional transformer and rectifier – are only about 96% efficient, meaning typically approximately 4% of the power is lost as heat during the conversion process. SSTs function as both the transformer and the AC/DC rectifier. They are significantly more efficient resulting in only about 2% of the power being wasted.
Given the need to maximize system capacity to support data centers or other large-scale projects, a highly efficient SST can provide cost savings, produce less heat, and lessen the amount of electricity that needs to be generated and transmitted for the application. In addition, SSTs are smaller than the conventional transformer-and-rectifier technologies so can be better used in settings where there are space constraints, such as urban areas
“SSTs take up less space,” says Lukic. “That can be important when considering large-scale projects such as data centers that can have a large footprint but also require their own power source in close proximity.”
NYPA, the nation’s largest state public power utility, collaborated with NC State to develop the transformer because of the significant potential benefits to its operations. SSTs enhance grid efficiency and support renewable integration, bidirectional power flow, and voltage regulation to handle increasing demand associated with data centers and electric vehicle charging stations.
Ramadan Elmoudi, Senior Research, Technology and Development Engineer at NYPA, who served as a project lead noted, “We learned through the project’s positive outcomes that solid state transformers can serve as another tool in our clean energy toolbox to enable New York State to operate and maintain a compact, efficient and resilient grid.”
“It is encouraging to see innovative technologies progress from university laboratories to full-scale testing,” said Drew McGuire, EPRI senior director of transmission and distribution research. “This collaboration was a powerful way to accelerate understanding and development of technologies like this SST.”
EPRI’s role in testing the technology is significant because the organization helps utilities test new technologies, like the SST, and then develop implementation strategies to adopt those technologies. Through this collaboration, this advancement can now be shared with the industry to benefit technology developers, utilities, and the public.
This work was initially funded by U.S. Department of Energy’s Transportation Technologies Office (TTO) under award DE-EE0008450. NYPA funded and contributed to the SST construction and in field testing aspects of the project.