Transactive Times: Three PNNL Researchers Featured in Special Issue
IEEE's Power & Energy Magazine focuses on transactive energy
The May/June 2016 issue of IEEE’s Power & Energy Magazine focuses on a topic that the grid gurus at PNNL hold dear: transactive energy.
For many others, though, transactive energy may be unfamiliar. In the Issue’s opening remarks, the editor acknowledges his web browser’s refusal to recognize the term. This special issue may help change that by demystifying transactive energy and putting it on the map as a novel approach for energy management.
Three of PNNL’s own leaders in the transactive energy continuum are featured in the issue. Check out the summaries below or read their full articles online.
- Ron Melton: The View from the Top of the Mountain: Building a Community of Practice with the GridWise Transactive Energy Framework
- Jeff Taft: A Tale of Two Visions: Designing a Decentralized Transactive Electric System
- Steve Widergren: A Society of Devices: Integrating Intelligent Distributed Resources with Transactive Energy
The View from the Top of the Mountain
Transactive energy is viewed differently by many. The GridWise Architecture Council (GWAC) recognized this, and likened the system to climbing a mountain. People can take different paths and start at different positions, but the view from the top remains the same.
In this vein, GWAC identified the need for a transactive energy framework and a set of consistent definitions. The framework, originally released in November 2013, made it possible for folks to learn about the mountain and experiences of other climbers, without climbing the mountain themselves.
GWAC defines transactive energy as “a system of economic and control mechanisms that allows the dynamic balance of supply and demand across the entire electrical infrastructure using value as a key operational parameter.”
The GWAC continues to help define and shape understanding of transactive energy. A tool called the “decision maker’s transactive energy checklist” is being created to help users evaluate options to determine possible investments in transactive energy systems. GWAC has also been partnering with PNNL in the development of a valuation methodology for transactive energy systems.
A Tale of Two Visions
As distributed energy resources (DERs)—such as wind turbines and solar panels—rapidly make their way onto the grid, two distinct visions for operating a decentralized, transactive electric system are emerging.
- Grand Central Optimization: this vision extends wholesale market structures used today by independent system operators or regional transmission organizations, but with greater amounts of DERs.
- Layered Decentralized Optimization: this vision offers a big change from how DER participation works today. Instead of having DERs bidding into and being dispatched from a single centralized system, a highly distributed market-control mechanism accounts for local dynamic conditions as well as global system needs.
Today, many assume that the future transactive energy system will operate on a version of the Grand Central Optimization. However, the alternative Layered Decentralized Optimization vision offers tier bypassing and scalability, among other benefits.
Though continued work is required to further layout this vision, Layered Decentralized Optimization is preferred by Taft and his co-authors, as it will help the future high-DER transactive energy electric system become successful.
A Society of Devices
End-use equipment is currently passively connected to the grid, but in the future, they will be actively involved in coordinating the operation of grid. Transactive energy makes this coordinated operation possible.
A landscape of approaches for interacting with distributed energy resources include:
- Top-Down Switching : Classical command and control, where a signal is broadcasted and devices, such as water heaters, are switched off during peak load periods.
- Centralized Optimization: Local equipment decisions are made centrally, but with two-way communication that take local data into consideration.
- Price Reaction: End users receive price data and can adjust equipment operations as they see fit.
- Transactive Control: Smart devices engage in trade at the distribution level, and intelligent controllers make decisions based on end-user preferences.
Transactive control has clear advantages overprice reactive systems and centralized optimization.
Several grid demonstrations, including the Olympic Penninsula Demonstration, GridSMART® Real-time Pricing Demonstration, and Pacific Northwest Smart Grid Demonstration, have shown the potential for transactive energy and provided insight towards future development. That said, many questions remain unanswered. Continued socialization and standards development efforts are underway.