men using equipment
Oak Ridge National Laboratory researchers Michael R. Starke, Ph.D., left, and Steven L. Campbell fine-tune equipment for managing power flow from commercial buildings, including (from left) an emulator, inverter, hub controller screen display, and subsystem monitoring equipment, with the hybrid AC/DC network visible in the background. (Photograph courtesy of Carlos Jones/ORNL, U.S. Department of Energy) 

By Catherine A. Cardno, Ph.D.

Researchers at the Oak Ridge National Laboratory in Tennessee have built and tested an energy hub capable of managing two-way power flow to and from commercial buildings. The bidirectional power electronics hub technology is the first step in creating a system that can better control power flow to and from commercial buildings that are equipped with such renewable systems as solar or wind — or a combination of the two — and other types of renewable energy generating systems.

The team, all at ORNL, includes Madhu Sudhan Chinthavali, Ph.D., head of the Energy Systems Integration & Controls Section, who led the team; Michael R. Starke, Ph.D., senior IEEE member, a power systems research engineer who was the project’s lead software architect; Steven L. Campbell, the project’s lead architect for the system’s integration; Ben Dean, a communications interface developer; Jonathan Harter, a hardware systems specialist; and Rafal Wojda, a magnetic systems specialist.

The system uses layers of integrated hardware and software to create a hybrid AC/DC power electronics hub that can optimize the performance of a building and its generating resources, according to Chinthavali. “We are creating an electric grid of the future that allows renewable energy to be deployed in the most effective way,” he explains. “With this new grid interface architecture, operators can control energy flows much more meaningfully, even when power generation is decentralized.”

The work was completed in the 52,000 sq ft Grid Research Integration and Deployment Center, an ORNL lab. Chinthavali leads the lab, which is dedicated to developing technological solutions to advance the efficient interaction among electric delivery systems, buildings, and vehicles, according to its website.

The hub acts as a router, or gatekeeper, to control how various interconnected elements — such as a solar array, a storage battery, an emergency generator, and a critical data center — share energy with one another.

The hub is composed of ORNL-developed software and power electronics hardware systems. To demonstrate a hub mimicking these components, ORNL researchers used a set of hardware emulators for solar, battery storage, and load and interconnected these to the hub to pull and push power to the grid, considering different use cases, according to Starke.

Photograph shows a large rectangular computer screen as well as a cabinet and desktop computers.
The power electronics hub manages power flow to and from commercial buildings using inverters, a hub controller, and subsystem monitors hooked to a hybrid AC/DC network. (Photograph courtesy of Carlos Jones/ORNL, U.S. Department of Energy) 

“This technology could be considered similar to that of a microgrid, which also manages two-way power flow,” explains Starke. However, the bidirectional power hub is “a step in a different direction,” he says. This is because “many microgrids rely on the energy stored in large rotating generators to maintain operations. However, the goal here is to move to more renewable low-carbon systems (that) do not have the same stored energy and utilize power electronic systems and sophisticated controls for integration.”

This means that faster dynamic control is needed so that power can flow in two directions rather than always in just one. “The power electronics converters are all designed to be bidirectional in terms of power and energy, but the resource management decides how the power flow is directed,” Starke explains.

By autonomously managing the power flow in both directions, the hub prevents fluctuations in supply and demand to the wider electric grid, according to material provided by ORNL. Renewable power generated on a commercial building could thus be used to charge a vehicle, for example, or a fully charged vehicle could be used to provide energy for a building that had lost power, Chinthavali explains.

This type of system has the potential to expand the types of locations where commercial buildings could be built and extend their distance from the existing power grid. The system could also be programmed to prioritize specific goals, such as optimizing cost savings for a commercial building or providing a consistent supply of power back to utilities.

Rather than all the equipment being specific to one vendor, the team has been careful to develop technology that is openly available and can be customized, depending on a building owner’s or operator’s goals. And as those goals evolve, the hardware could be switched and the software adjusted to best meet any new needs that arise. “The power electronics hub is plug and play and autodetects and optimizes resource utilization based on user inputs,” Starke says.

The demonstration hub was developed as a “behind the meter” prototype for commercial property owners, but it could be scaled up in either direction to become an “in front of the meter” solution for grid owners too, according to Chinthavali.

The project has led to three patent applications, Chinthavali says. As part of the next steps, the pilot will be scaled up using higher-power, commercially available components developed in partnership with utilities in the southeastern part of the country.

The team will also examine new data collection techniques, the integration of artificial intelligence, and other mechanisms to improve the robustness of operations, according to Starke.

Catherine A. Cardno, Ph.D., is the editor in chief of Civil Engineering Online.

This article first appeared on Civil Engineering Online as “Bidirectional energy hub successfully demonstrated in Tennessee.” It appeared in the March/April 2023 issue of Civil Engineering as “Bidirectional Energy Hub Piloted.”