Regional Project Reveals the Potential of Transactive Control
PNNL experiments test new methods for managing the nation's buildings and energy system
Recent results from two PNNL experiments show promise for advancing both the “clean” and "transactive" aspects of energy management—at the intersection of buildings, the power grid and distributed energy resources (DERs).
The Clean Energy and Transactive Campus project, led by Pacific Northwest National Laboratory and involving the University of Washington and Washington State University, was launched in late summer 2015. The project has been applying transactive control technology and methods to test various concepts. The goal is to improve efficiency and comfort in buildings, make the grid more reliable, and enhance integration of DERs, such as wind and solar power, with the grid—all at a regional scale. The project ultimately will produce a blueprint to replicate CETC methods across the nation, as well as a clean energy testbed in Washington State.
As part of the project, PNNL conducted four unique experiments in buildings on its campus. Two experiments— Intelligent Load Control and Passive and Active Diagnostics for Building Efficiency—were featured in previous EED Research Highlights; results from the other two—addressing transactive markets and renewable integration, respectively, are showcased below.
Transactive Control and Coordination of Building Energy Loads
This experiment was successfully deployed in one building’s air handling unit (AHU), with plans now to extend the approach to other buildings at PNNL.
This experiment uses a PNNL-developed algorithm and the VOLTTRON™ software platform to essentially create markets within different building zones and devices as part of an automated, real-time process. For example, an air handling unit (AHU) monitors a price signal, obtains electricity at a certain cost and then sells its product—cool air—to zones within the building that electronically “bid” on the cooling capacity based on price and desired occupant comfort levels.
Under this approach, the AHU or other controllable loads respond to a price-capacity curve that relates the current energy price to the predetermined comfort expectations of building occupants. The curve influences AHUs to either reduce power load to balance cost and comfort objectives, or in cases of abundant, economical electricity, perhaps increase consumption to perform tasks in advance, such as pre-cooling a building.
In the experiment, researchers used a utility-originated flat rate to establish the transactive control energy price, but in the future expect to employ a signal that better represents price, supply and demand fluctuations.
Integration of Distributed Renewable Energy Resources
Large-scale use of clean, renewable energy is highly desirable, but the intermittency of these resources can disrupt power grid operations. One concern involves buildings that use photovoltaic (solar) panels for supplementary power. In cases where clouds appear and solar generation suddenly drops, the grid must quickly step in and make up the loss.
The concept behind the experiment involves control of building loads, such as variable-frequency-drives on fans in AHUs and packaged rooftop units (RTUs), to mitigate the lost generation. A PNNL-developed algorithm, used in concert with VOLTTRON™, tracks signals from solar generation and the power system, analyzes resulting data, and quickly adjusts fan speed to reduce or resume power consumption. In addition to fans, this method could be applied to other types of loads, such as water heaters, pool pumps and electric vehicles.
The experiment successfully developed control methods that can command a building fan to track solar production, adjust operation accordingly and maintain building occupant levels within an acceptable range—ultimately benefiting grid operations.
User guides for this and the other three CETC experiments are being developed and will provide the direction necessary for other entities to implement these methods.
CETC Phase 2: Expanding to Ohio
In the second phase of the project, which is getting under way, the four experiments will be extended to UW and WSU for additional testing, as well as to two new partners in Ohio—Case Western Reserve University and the University of Toledo. The Ohio schools each plan to deploy at least two of the PNNL experiments in campus buildings and identify ways to improve upon the associated algorithms and methodologies. The NASA Glenn Research Center in Ohio also joins Phase 2, with a focus on use of modeling and simulation to explore new transactive strategies for balancing power grid operation with the center’s unique distribution system.
The CETC project is a part of the Energy Department’s larger Grid Modernization Initiative (GMI), a comprehensive Energy Department and partner collaboration to accelerate the development of technology, modeling analysis, tools, and frameworks to help enable grid modernization adoption. National Laboratories are participating across GMI’s technology areas in a coordinated strategic partnership called the Grid Modernization Lab Consortium (GMLC). Funding for CETC is provided by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (Building Technologies Office), Office of Electricity Delivery and Energy Reliability, and the Washington State Department of Commerce.