IEEE Electrification Magazine - March 2014 - 9

interconnection. ieee members have
approved eight complementary standards, including ieee 1547.4 and ieee
1547.8, which may be affected by a
currently active amendment process.
in recognition of the measured
pace that characterizes standards
development and the speed with
which microgrid technology is
advancing, ieee P1547a-Amendment 1
was introduced to speed up high priority changes to ieee 1547. This
amendment updates practices
regarding voltage regulation and
responses to abnormal voltage and
frequency conditions on the grid. As
of this writing, the amendment has
cleared the balloting process and is
subject to a comments period. if
approved, as expected, the changes
in this amendment will go into effect
in early 2014, followed by a comprehensive overhaul of ieee 1547 to
resolve the additional issues that
surfaced during work on ieee P1547aAmendment 1.
Two specific changes in ieee 1547
address microgrids. dg systems
henceforth may participate in voltage regulation via changes in real
and reactive power supplies, allowing
utilities to integrate dg as grid-supporting resources. (Before this
change, dg was not allowed to
actively regulate voltage at the point
of common coupling.) This change
permits the microgrid sponsor to regulate voltage and save energy in
cases where the utility does not practice conservation voltage reduction.
Whereas ieee 1547 defined recommended practices for dg system
behavior in response to abnormal
frequency conditions-i.e., spelling
out when a dg system must stay
connected and when it must disconnect-amendments were fast
tracked because of evolving concerns. A rapid increase in the penetration of Pv rooftop systems in
pockets around the country presented utilities with the possibility that
perhaps hundreds of dg systems
might disconnect at the same time

standards for intentional islanding.
due to a dip in frequency on the grid.
Pending changes in the standard
if an unscheduled outage at a major
should clarify how the two effects
power plant caused the underfrediffer or relate.
quency, then a sudden loss of dg
Anti-islanding, a crucial safety
power could exacerbate the situation.
function of protective systems, will
These amendments will enable
remain as a provision of the amendmicrogrids to better meet utility intered 1547 standard. grid-tied, stanconnection concerns to operate more
dards-compliant dg systems typicalefficiently and, thus, encourage their
ly are grid activated, meaning that
development. The first amendment
they automatically
provides for microgrid
shut down when an
integration with disAnti-islanding, a
outage occurs, pretribution control syscrucial safety function
venting unintentiontems and allows a
of protective systems,
al islanding.
microgrid to serve
An amended ieee
grid-support funcwill remain as a
1547
will likely provide
tions, a direct answer
provision of the
specific provisions to
to specific utility conamended 1547
enable intentional
cerns. The second
standard.
islanding in cases
amendment allows a
where a microgrid or
microgrid to remain
other islandable dg
grid-connected,
source is designed to function both conwhich will preclude the introduction
nected to and disconnected from the
of unneeded backup generation for
grid. For instance, ieee 1547 originally
the utility. if an interconnected
encouraged highly sensitive trip-off setmicrogrid is feeding power onto the
tings. The downside of that approach is
grid, the ride-through (second)
that a minor fault could lead to dg
amendment contributes to avoiding a
deactivation. given the high penetrabad-to-worse scenario.
tion of dg, such hair-trigger settings for
Further work on standards will be
anti-islanding can lead to problems.
needed. standard information modAlso, those settings represent a nuiels for microgrid control point funcsance for systems designed to isolate
tionality are in the early stages of
themselves and initiate backup generadevelopment. The vision of a distribution upon sensing a system fault. The
tion system comprising multiple,
proposed amendments to ieee 1547 are
interactive microgrids in support of
focused on allowing a wider ridereliability for both distribution and
through tolerance so that dg and
transmission systems is getting closmicrogrids can continue generation
er to reality. These standards will take
despite fluctuations in grid frequency.
time, largely because technologies
in other words, the main differand applications are still maturing.
ence between anti-islanding and
sophisticated smart grid applications
intentional islanding is that once a
in this context will require uniform
system is intentionally islanded, antistandards as the need for interoperaislanding requirements no longer
bility increases.
apply. The islanded dg system is disIslanding and Anti-Islanding
connected from the grid and, thereone important clarification is in
fore, is no longer a safety concern.
order here. The terms islanding and
ieee 1547.4 will contain recommendanti-islanding can be confusing.
ed practices for intentional islanding,
ieee 1547's anti-islanding tenets
and the forthcoming 1547.8 standard
were written to prevent unintentionaddresses the functionality of small
al islanding of grid-connected genergenerators such as microgrids, which
ation. separate provisions provide
are designed to intentionally island.

IEEE Electrific ation Magazine / MARCH 2 0 1 4

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