IEEE Power & Energy Magazine - November/December 2017 - 59

taking advantage of the essential reliability services
DER can provide.

Revising Interconnection Standards
IEEE standard 1547 (abbreviated "1547") is the de facto
interconnection standard for DERs in the United States.
Developed as a distribution system safety and power quality
standard assuming low penetration, it was published in 2003
as a voluntary industry standard for interconnecting DERs
with electric power systems. The standard was amended in
2014 to allow for advanced DER grid support such as steady-
state voltage control and disturbance ride-through. Currently
being balloted, the proposed 1547 revision aims at mandat-
ing and specifying new DER interconnection and interop-
erability requirements. By mandating requirements such as
disturbance ride-through, the revision is designed to avoid
problems such as the German 50.2-Hz issue mentioned in the
"Bulk System Impacts in a Nutshell" section.
The technology neutrality of 1547 does not allow different inter-
connection requirements for inverters and rotating machines as
is typically the case for large-scale generating facilities, in state

May Ride-Through
or May Trip

62.5

62.0 Hz

62.0

Shall Trip
0.16 s

1,000 s

2

Mandatory Operation
Capability

61.0

Frequency (Hz)

66.0 Hz

299 s

61.5

60.5

Categories I, II, and III
(Harmonized)

66.0 Hz

63.0

rules, and in other parts of the world, e.g., Europe and Germany.
Yet, various DER types differ in their inherent ability to ride
through disturbances, and DER deployment varies regionally.
The one-size-fits-all approach from past grid codes is no longer
appropriate: a more flexible approach is needed.
Therefore, the proposed 1547 provides a framework for
Authorities Governing Interconnection Requirements (AGIR)
to assign appropriate DER disturbance ride-through perfor-
mance requirements. A limited number of groupings of sets
of requirements-standardized operating performance cate-
gories-specify technical capabilities and settings for a DER
under normal and abnormal operating conditions. The former
are designated by alphabetical characters (categories A and B)
and the latter by Roman numerals (categories I, II, and III).
This concept is shown in Figure 9.
The 1547 abnormal operating performance categories
I, II, and III will group a set of requirements that specify
technical capabilities and settings for DER disturbance ride-
through ability, as shown in Table 1 (and illustrated in Fig-
ures 10 and 11). Category II specifies technical minimum
requirements for voltage ride-through as recommended

61.0 Hz
1,000 s
1
May Ride-Through
or May Trip

180 s

60.6 Hz

60.0
59.5
59.0
58.5
58.0

Continuous Operation Capability
(V/f ≤ 1.1)
(Subject to Requirements of Section 6.4.2.6)
Legend
Mandatory Operation
Capability

57.5

57.0 Hz

Range of Adustability
Default Value
Shall Trip Zones

57.0
56.5

May Ride-Through
or May Trip

56.0
0.01

0.1

2

180 s

0.16 s

May Ride-Through or
May Trip Zones

1

59.0 Hz
1,000 s

299 s

Shall Ride-Through Zones
and Operating Regions
Describing Performance

May Ride-Through or May Trip

1,000 s

Shall Trip
50.0 Hz

1

10

100

50.0 Hz

1,000

Time (s)

figure 11. The frequency ride-through requirements for DER in categories I, II, and III. (Source: Sponsor-Ballot Draft
Standard for Interconnection and Interoperability of Distributed Energy Resources with Associated Electric Power Systems,
IEEE P1547/D6.7.2, May 2017.)
november/december 2017

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