I don’t think I agree with any of the “interesting additions”,
except that every microgrid should have some storage to allow meeting typical
demand requirements. I’m not sure what “driven by DER” means. Certainly there
has to be some DER. The definition and value of high reliability is in the eyes
of the beholder.
David
From: Anne Hendry
[mailto:ahendry@pacbell.net]
Sent: Friday, March 19, 2010 2:59 PM
To: emix@lists.oasis-open.org
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
-A
Holmberg, David wrote:
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.
David
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.
-A
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."
http://eetd.lbl.gov/CERTS/pdf/mg-pesc04.pdf
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
http://www.naesb.org/pdf4/interimsmartgridroadmapnistrestructure.pdf
"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.
http://certs.lbl.gov/certs-der-micro.html
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.
http://green.venturebeat.com/2009/10/29/microgrids-a-21b-market-in-the-making/
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.