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Subject: Re: [emix] defining terms -- microgrid

Yes, the primary recurring attributes seem to be:

- can operate independently from grid or in parallel
- can seamlessly move from one mode to the other
- independently controlled at the local level, no need for central control
- driven by DER, co-locates generation and load
- highly reliable

Interesting additional notes from the survey presentation at the same site are the 'points of varying agreement'
- generation capacity must be < 1 KW
- must contain > 1 generation source
- must connect to the grid at a single point
- must contain storage (batteries, etc)
- must be able to meet full load requirement


Holmberg, David wrote:
ECA909905BF0314CB16441980AFC5CE607A5A054D9@MBCLUSTER.xchange.nist.gov" type="cite">

They all agree as far as I can tell. I like the http://www.electricdistribution.ctc.com/microgrids.htm, along with the EI idea of hierarchy put together.




From: Anne Hendry [mailto:ahendry@pacbell.net]
Sent: Friday, March 19, 2010 2:49 AM
To: emix@lists.oasis-open.org
Subject: [emix] defining terms -- microgrid


We've been using the term microgrid (among others) frequently and today it came up again but with the thought it might also be applicable to subsystems within the 'macrogrid'.   At the same time, in the Dutch 'microgrid' paper, they use the term Virtual Power Plant (not so much a microgrid, but more of a role a microgrid may assume).  'Microgrid' is used and defined differently by different entities and the definition is evolving, as are most in this space, and new terms are devleoping.  Perhaps it would be helpful to start a glossary for terms like these we may use in the spec so everyone understands the definition as they are used by EMIX?  The defining process may have the added value of generating more clearly articulated scope and price communication requirements.

For instance, below are several different defs/characteristics for microgrid I've run across recently.  Each specs a different set of characteristics from which we could generate an amalgam of those (and any from other sources) characteristics most relevant to EMIX and perhaps then define some use cases using these characteristics to drive element declarations/definitions?

Just throwing this out, as an example, to start gathering glossary terms.


EI spec:
"Small, local versions of the bulk power grid that optimize the local distribution system and may include local generation and storage.  A microgrid may contain smaller microgrids and may be part of a larger microgrid; communication interface at the edge of each microgrid is the same."

Subsystem of generation and associated loads that can separate from the distribution system to isolate from disturbances without harming the transmission grid's integrity and providing higher local reliability by islanding generation and load together.  Allows for local control of distributed generation, eliminating the need for central dispatch.

From NAESB report to NIST
"electric island"

>From http://www.electricdistribution.ctc.com/microgrids.htm
A microgrid, a local energy network, offers integration of DER with local electric loads, which can operate in parallel with the grid or in an intentional island mode to provide a customized level of high reliability and resilience to grid disturbances. This advanced, integrated distribution system addresses the need for application in locations with electric supply and/or delivery constraints, in remote sites, and for protection of critical loads and economically sensitive development.  By operating microgrid in the islanding mode, critical loads can continue to operate, impervious to grid disturbance events.

CERTS Microgrid:
A key feature of a microgrid, is its ability, during a utility grid disturbance, to separate and isolate itself from the utility seamlessly with little or no disruption to the loads within the microgrid (e.g., in the CERTS Microgrid concept, no impacts on power quality). Then, when the utility grid returns to normal, the microgrid automatically resynchronizes and reconnects itself to the grid, in an equally seamless fashion.  A critical feature of the CERTS Microgrid is its presentation to the surrounding distribution grid as a single self-controlled entity. A CERTS Microgrid appears to the grid as indistinguishable from other customer sites that do not include DER. This presentation means that the microgrid avoids many of the current concerns associated with integrating DER, such as how many DER the system can tolerate before their collective electrical impact begins to create problems like excessive current flows into faults and voltage fluctuations.   The peer-to-peer concept insures that no single component, such as a master controller or a central storage unit, is required for operation of the microgrid. Therefore, by its very design, the CERTS Microgrid can continue operating with loss of an individual component or generator.

>From http://www.electricdistribution.ctc.com/microgrids.htm
http://www.electricdistribution.ctc.com/pdfs/Microgrid_Assessment_Phase_1.pdf : (slide 4, also more detail at slides 9-11)
No clear definition, but characteristics include ability to operate 'islanded' or 'grid parallel', and to switch seamlessly between these two modes, and to include significant DER capacity; driven by DER technology rather than by energy service requirements.

Smaller-scale electrical systems spanning college campuses, municipalities and business parks, where energy is generated, stored and very closely managed on an intensely local level.  Without being hooked into one of the larger national grids, there are less likely to be disruptions due to peak demand or excessive power loads.  Easier to do DR.  Can store enough energy to keep power flowing during blackouts or other disruptions. This makes them ideal for emergency services, hospitals, and of course, the military.

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