IEEE Electrification - December 2021 - 36

system as spinning generators are
replaced by renewable energy
resources and energy storage, all
of which connect to the network
through power electronics. The fast,
bidirectional response of energy storage
can contribute to the mitigation
of any stability issues, but such
responses by multiple resources must
be properly coordinated.
Standards are essential in addressing
these issues. Interconnection
standards provide widely accepted,
consensus-based requirements and
best practices for connecting resources
to power systems, and they help to
create consistency in policy across
multiple jurisdictions. IEEE has been writing interconnection
standards for decades, starting with IEEE 929-1988,
which dealt exclusively with distribution-connected, residential
photovoltaic systems, focused mainly on potential
power quality issues, and was only seven-pages long,
including an annex. Since then, the number, scope, and
length of standards have increased considerably and now
cover energy storage connected at the distribution or
transmission levels.
Large-scale energy storage will often be implemented
in the form of inverter-based resources (IBRs) interconnected
with transmission or subtransmission systems,
and there is a group of standards under development for
these interconnections. The first of these, IEEE P2800,
Draft Standard for Interconnection and Interoperability of
Inverter-Based Resources Interconnecting With Associated
Transmission Electric Power Systems, is expected to be
published later this year. (Note that the document is subject
to change as it goes through the balloting process, so
statements in this article may not accurately reflect the
content of the final document.) IEEE P2800 defines a set
of minimum capabilities and performance requirements
for all IBRs connected to transmission or subtransmission
systems. This new standard was crafted with energy
storage in mind and includes multiple examples, explanatory
footnotes, and other materials illustrating the
Transmission
G
IBR
IEEE P2800 (2021)
IEEE P2800.1
IIEEE P2800.2
IEEE P2800.1
EEE P2800.2
Transmission
Subtransmission
IBR
Subtransmission
Interconnection
standards provide
widely accepted,
consensus-based
requirements and
best practices for
connecting
resources to power
systems.
application of P2800 to transmissionconnected
energy storage. This standard
also addresses several common
applications of large-scale grid energy
storage, such as hybrid plants (e.g.,
plants that include both photovoltaics
and energy storage) and fast frequency
response.
IEEE Std 1547-2018, IEEE Standard for
Interconnection and Interoperability of Distributed
Energy Resources With Associated
Electric Power Systems Interfaces, is the
standard that applies at the distribution
level, whether to individual systems
or aggregations that act as virtual
power plants. This document is a revision
of IEEE 1547-2003. The 2003 version
of the standard was written in an environment in
which the aggregate power level of DERs on the system
was very low, such that they did not have a discernable
impact on transmission system behavior, and thus, the
2003 standard took the approach of tripping DERs offline
for many abnormal system conditions, leaving the system
to handle the condition. By the time the 2018 revision was
completed, the number of DERs on the system had
become sufficiently large that transmission impacts were
already evident, and thus, the 2018 revision contains
extensive requirements for capabilities that support the
bulk system, including ride-through requirements for
DERs to stay online over a much broader range of conditions
than before. Further addressing the unique characteristics
of distributed ESSs-with bidirectional flow of
both real and reactive power in the context of IEEE Std
1547-is the focus of a new standard, IEEE P1547.9, Draft
Guide to Using IEEE Std 1547 for Interconnection of Energy Storage
Distributed Energy Resources With Electric Power Systems,
expected to be published in 2022. An ESS connected at the
distribution level is referred to in this document as an
energy storage DER (ES DER).
The respective scopes of these interconnection stanIEEE
1547-2018
IEEE 1547.1-2020
IEEE P1547.2
IEEE P1547.3
IEEE P1547.9IEEE P1547.9
IEEE 1547-2018
IEEE P1547.2
IEEE P1547.3
Figure 5. The IEEE standards relating to ESS interconnection.
36
IEEE Electrification Magazine / DECEMBER 2021
dards and their subsidiary " dot-standards " are shown
graphically in Figure 5. The transmission-level requirements
set by IEEE P2800 and the distribution-level requirements
set by IEEE 1547-2018
do have some significant differences.
One key example of importance
to energy storage is the requirement
for fast frequency response.
At the distribution level, IEEE 15472018
does not explicitly require fast
frequency response but does require
the capability to provide
frequency-droop response (a frequency
response proportional to
Tf). However, the shortest response
time allowed for this droop
Distribution
ALL DER
ALL DER
Distribution
IEEE Electrification - December 2021

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