Download February 25, 2008

North American Energy Standards Board
801 Travis, Suite 1675, Houston, Texas 77002
Phone: (713) 356-0060, Fax: (713) 356-0067, E-mail: [email protected]
Home Page: www.naesb.org
January 23, 2015
TO:
NAESB Advisory Council
RE:
Advisory Council Meeting – Agenda Item 7 – Microgrid Integration
Request: With the expanded use of smart grid technologies and opportunities for microgrids to operate
independently as part of the larger power grid, would model business practices that support the participation of
microgrids within the current independently owned utility market structure be helpful?1
Microgrid: A microgrid is a group of interconnected loads and distributed energy resources within clearly defined
electrical boundaries that acts as a single controllable entity with respect to the grid and that connects and
disconnects from such grid to enable it to operate in both grid-connected or “island” mode.2 A microgrid generally
operates while connected to the grid, but importantly, it can break off and operate on its own using local energy
generation in times of crisis like storms or power outages, or for other reasons. A microgrid can be powered by
distributed generators, batteries, and/or renewable resources like solar panels. Depending on how it’s fueled and
how its requirements are managed, a microgrid might run indefinitely. A microgrid connects to the grid at a point of
common coupling that maintains voltage at the same level as the main grid unless there is some sort of problem on
the grid or other reason to disconnect. A switch can separate the microgrid from the main grid automatically or
manually, and it then functions as an island. 3
Considerations:
1. Most microgrids require a centralized control system and a balanced energy portfolio in order to run
reliably and economically; however, a majority of the existing microgrids in existence are customer-owned
rather than utility-owned. As utilities are responsible for maintaining a level of reliability and the
distribution facilities that serve the microgrid, they typically operate or direct the microgrid control system.
2. The costs for the use of the distribution system typically recovered through conventional kWh charges are
not recouped with the participation of microgrids. Is this an issue that could be partially addressed through
national or state driven standards in support of policies enacted at wither the national or state level?
3. Some customer-owned microgrids can act as a Qualifying Facility under Public Utility Regulatory Policies
Act (PURPA)4, which allows them to buy and sell power to the local utility at competitive rates, but when
the microgrid consists of multiple entities, with electricity being generated by some and delivered to others,
the economic framework for how costs and ownership rights are shared can be incredibly complex.5 Also,
depending on their structure, a microgrid may not be covered under PURPA and will have to meet FERC
and balancing authority requirements.
4. There are technical challenges related to connecting microgrids to the larger grid. The installation of the
proper equipment at the point of common coupling is a requirement to ensure the seamless transitions
between islanding and being connected. Miscues could create phase and frequency issues on the larger
grid. Also, power quality and voltage control issues in the microgrid may affect the larger grid.
5. Is a national standard helpful in area where there are many existing regulations that vary by jurisdiction or
is this issue more appropriately addressed at the state/regional level, or is it a combination of both?
1
Email received from Toby Considine, an active participant in smart grid standards development for OASIS, on January 12th
"Summary Report: 2012 DOE Microgrid Workshop," DOE EERE, Chicago, 2012.
3 Taken from the Department of Energy website: http://energy.gov/articles/how-microgrids-work
4 To be a Qualifying Facility, a microgrid must consist of renewable generation of less than 80 MW or be a cogeneration facility
that generates both electricity and useful thermal energy.
5 Taken from EPRI’s Microgrids: A Primer: http://nyssmartgrid.com/wp-content/uploads/Microgrid_Primer_v18-09-06-2013.pdf
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Advisory Council – Agenda Item 7: Microgrid Integration
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