POWER May 2016 - 42

DISTRIBUTED ENERGY RESOURCES
Stacking Microgrid Benefits
Microgrid developers and financers often
talk about the importance of " pancaking "
value streams to make a project financially
viable. Just providing backup power,
for example, is unlikely to make a project
pencil out. More recently, " resiliency " for
a customer or community-supported by
the electricity reliability provided by a
microgrid-has become a primary motive
for considering microgrid development.
The problem is that, while few would argue
against resiliency, there's currently no way
to make it a bankable benefit for financing
purposes.
That's why everyone with any experience
in this energy supply area agrees on
the importance of finding multiple value
streams. For example, looking at Figure 3,
that might mean bundling rooftop and carport
photovoltaic generation with battery
storage, electric vehicle (EV) charging/
energy storage, and a small fossil-fueled
genset-all of which might enable (where
allowed) the microgrid to earn revenue
from selling ancillary services to the grid,
lowering overall electricity costs, providing
tenant/customer EV convenience as
well as power supply security.
Note that each wholesale energy market
and state has different rules for what sorts
of generation can be owned by customers
behind the meter and how power can be
moved over what geographic lines. States
also vary in interconnection requirements,
net metering rules, and what distributed
energy resources a utility may own behind
the meter. All those factors combine to
create an enormous amount of variability
in terms of determining what's legally-
let alone financially-viable for a new
microgrid.
multiple loads with complementary demand
profiles.
Model Before You Build. For years,
microgrid developers have recognized that,
although the parts of a microgrid are all
familiar, designing an effective installation
(especially one with multiple generation
and storage components) poses new sorts
of system integration challenges. Especially
in an arena where you have new players
and familiar players in new roles, there are
going to be unknown interconnection behaviors
that can potentially damage expensive
equipment. The more you model, the
42
3. Potential microgrid value
streams pancaked. This is not an
exhaustive stack of microgrid benefits, and
not all value streams will be options for all
projects. Some benefits will accrue to different
parties (the customer and the grid
operator, for example). You could think of
the different pancake colors as different
" flavors " of benefits: green represents
revenue from external/offsite sources; yellow
represents customer costs avoided or
lowered by use of a microgrid; and blue represents
social and environmental benefits
that may be hard to assign a dollar value to.
Source: POWER
Garner local power credentials
Enhance environmental credentials (with
renewables lowering emissions)
Strengthen the grid (with strategic siting for
feeder voltage support)
Provide backup power / reliability / resiliency to
avoid economic losses from outages
Enhance power quality (avoiding business
interruption)
Provide a hedge against future power supply
costs
Provide heating and cooling
Self-supply power (not always currently cheaper
than grid power)
Sell ancillary services to the grid (typically,
frequency regulation)
Avoid peak prices / receive demand response
payments
Sell power to the grid (from the entire microgrid
or parts)
Claim tax credits for renewable generation
Win microgrid development grants (typically, state
or local)
As a result, especially when you look
beyond building-level microgrids, project
design is likely to require customization
for the foreseeable future.
less you'll have to figure out while operating
a microgrid. One new tool to assist with
this task is the Microgrid Controller Hardware-in-the-Loop
Demonstration Platform
(see the images at the top of this story)
developed at the Massachusetts Institute of
Technology's (MIT's) Lincoln Laboratory
(Lincoln Lab).
Several researchers involved in the Lincoln
Lab project were on hand at the Microgrid
Summit to display and discuss their
" physical model " of a microgrid-essentially
a test integration model. Researchers hope it
will be used as a development, deployment,
www.powermag.com
and standards-testing platform to help accelerate
microgrid deployments, MIT's Kendall
Nowocin explained. The platform uses the
configuration of an anonymized real-world
power system (code name " The Sheriff " ) operating
as a microgrid.
There are three levels of control on a
grid of any size, Nowocin told POWER:
primary-for performing equipment protection
at microsecond to millisecond speeds,
secondary-for controlling forcing functions
(frequency, voltage, power, power factor) at
millisecond to second speeds, and tertiary-
the supervisory level that doesn't directly
control equipment, operating at seconds to
minutes speeds. The Lincoln Lab model can
import a one-line diagram (schematic) of any
existing or planned microgrid in the 1-MW to
50-MW range to test how microgrid controllers
(the tertiary level) from various vendors
would behave-thereby eliminating many of
the current unknowns that can spell trouble
for one-off projects.
Anyone, including vendors, can use the
" Sheriff " model, and the lab planned to release
the model's source code publicly in
April (contact G73-HIL-PLATFORM@
ll.mit.edu). Phillip Barton, director of Schneider
Electric's North American Microgrid
Competency Center, said he recommends
working with Lincoln Lab and that, as his
company moved into hardware-in-the-loop
testing, they learned it is less risky than onsite
testing.
Consider Different Configurations for
Different Purposes. Although there are
benefits to standardization and replicability,
some circumstances may call for atypical solutions.
Direct current (DC) microgrids are
one example.
Andrew Yip, a business development
manager with Robert Bosch (Bosch), told
POWER his company is developing highvoltage
building-level DC microgrids. It
has two systems in place in North Carolina
(one at Fort Bragg) and two more going in
this year, one at a Bosch facility in Michigan
and another supported by a California
Energy Commission (CEC) grant for a
project in Los Angeles.
By coupling solar and storage with heavy
AC loads that are converted to DC loads-
especially LED lighting, industrial fans, and
forklift chargers (Figure 4)-Bosch says it
can save 3% to 4% on conversion losses. That
can add up to substantial energy savings for
businesses.
Reliability Is Always Important. Whether
you are designing a microgrid primarily
for backup power or to participate in energy
markets to reduce power purchase costs, reliability
as a means of securing resiliency for
a building, process, or community, should alPOWER
| May 2016
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POWER May 2016

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