This piece was originally published in the September 2016 issue of electroindustry.
Steve Griffith, PMP, NEMA Industry Director, NEMA
A new NEMA report, Powering Microgrids for the 21st-Century Electrical System, introduces the concept of microgrids as an integral component of the power delivery system of the 21st century.
This newer understanding contrasts with the earlier, more limited view of microgrids as islanded systems of generation and load, valued mostly for their ability to disconnect from the grid and serve individual customer facilities during outages. Microgrids are now seen as part of distribution system operations, interacting with the distribution grid through advanced control and distribution management systems. Microgrids will play a major role in grid modernization in an evolving regulatory framework.
This report first presents the structure of the electric power grid and explains the evolution of the distribution grid from a passive to an active one. This change is the result of the deployment of distributed generation—in part based on renewable resources, including solar and wind power, and electrical storage devices, known as distributed energy resources (DER)—and the implementation of portions of the smart grid agenda. These enable the implementation of distribution automation concepts and advanced controls at the end-user premises, including smart appliances and demand response.
The presence of DER and intelligent control allow for the aggregation of DER into virtual power plants and, when these are used to directly feed loads, into microgrids. Microgrids can therefore be seen as the building block for a new approach to configuring modern distribution systems.
Microgrids present a number of advantages associated with the presence of DER in serving loads, including greater reliability, higher power quality, and increased autonomy with respect to the main grid, making them more resilient in extreme weather conditions. Their deployment is made possible by the availability of newer equipment, enabling the implementation of intelligent generation, storage, and loads managed by the microgrid controller. These provide added flexibility in meeting energy delivery requirements.
There are many possible configurations of microgrids for deployment in residential, community, commercial, and industrial environments that use a combination of available intelligent equipment and control devices. Given the many identifiable benefits of microgrids, the market opportunities have been steadily growing, particularly in the United States. This report discusses the business case for microgrids and provides general information related to the cost of components and systems.
There are many technological advances that will facilitate the deployment of microgrids. In particular, developments are occurring in power conversion systems, rotating and static converters (particularly smart inverters), energy storage devices, advanced control systems, and the supporting sensors and communication infrastructure.
The standardization efforts in DER and microgrids are discussed in this report, and the need to accelerate this effort is emphasized. The availability of standards will greatly simplify the implementation of microgrids and lead to reductions in the cost of equipment and controllers. In addition, the regulatory framework needs to evolve to allow microgrids to play a larger role in the distribution grid operation and contribute to the grid modernization efforts.
Finally, this report ventures to articulate a vision for the future of microgrids, based on the assumption that the technology and the regulatory framework continue to evolve, and offer a favorable context for their accelerated deployment.
MGRD 1-2016 Powering Microgrids for the 21st-Century Electrical System is available at no cost on the NEMA website.Read the September 2016 issue of electroindustry.