conference papers · requirements of ieee std. 1547, however, in most cases there is considerable...
TRANSCRIPT
Conference Papers
Comparison of Some Randomly Selected Utilities InterconnectionRequirements and the Compliance with theIEEE Std. 1547 - Interconnection Guidelines
Keith Malmedal P.E., P.K. Sen Ph.D.
Paper No.08 C3
C3
978-1-4244-2148-0/08/$25.00 ©2008 IEEE
C3-1
Abstract—Electric Utilities permitting interconnection of
generation (small and/or large) on their power systems have long
had standards which any entity wishing to interconnect has to
meet. Recently the growing importance of distributed generation
(mostly less than 10MVA), especially using renewable sources,
has prompted the creation of IEEE Std. 1547 which sets
requirements and guidelines for interconnecting a distributed
resource with an electric power system. This paper will examine
the requirements of the Std. IEEE 1547 and compare them with
the interconnection requirements currently used by a number of
randomly selected utilities.
Index Terms—Distributed Energy Resources, Generators,
Interconnection, Renewable Energy.
I. INTRODUCTION
EEE Standard 1547-2003 titled “IEEE Standard for
Interconnection Distributed Resources with Electric Power
Systems” was developed in its own words to “provide a
uniform standard for interconnection of distributed resources
(DR) with electric power systems (EPS). It provides
requirements relevant to performance, operation, testing,
safety considerations, and maintenance of the
interconnection“[1]. The standard also states that the
requirements contained within it “are universally needed for
interconnection of DR, including synchronous machines,
induction machines, or power inverters/converters and will be
sufficient for most installations.”
Many utilities had developed their own standards some of
which have been in use for many years prior to the IEEE
Standard Guideline. An examination of a variety of
interconnection standards shows that there is a wide variation
in the acceptance of the requirements stated in the Std. IEEE
1547.
This paper will examine, in detail, a number of such
randomly selected guidelines and compare them with the
Manuscript submitted January 18, 2008 for 2008 IEEE Rural Electric
Power Conference, April 28-29, Charleston, SC.
This work was partially supported by the NSF IUCRC Power Systems
Engineering Research Center (www.pserc.org).
K. Malmedal is a principal engineer with NEI Electric Power Engineering,
Arvada, CO 80001 USA. and a doctoral student at Colorado School of Mines,
Golden, Colorado 80401, e-mail: [email protected]
P. K. Sen is Professor of Engineering with Colorado School of Mines,
Golden Colorado 80401 e-mail: [email protected]
IEEE Std. 1547 Guideline. An analysis is also added with
respect to these data to enhance the understanding and
applicability of these requirements.
In 1978 the Public Utility Regulatory Policies Act (PURPA)
was passed which encouraged the creation of non-utility
owned generation and cogeneration. The Energy Policy Act
of 2005 modified PURPA and its provisions will further
encourage the creation and interconnection of distributed
generation on utility facilities. These developments have lead
to the creation of IEEE Std. 1547 and the further creation of
utility interconnection standards for power plants and
distributed resources which wish to connect with utility
facilities.
II. INTERCONNECTION REQUIRMENTS AND IEEE STD. 1547
The table shown at the end of this paper in Appendix II is
designed to quickly show how a variety of utilities and state
requirements for generation interconnection compare with the
requirements of IEEE Std. 1547. Of the standards (available
in public domain) examined only two utilities completely
required the implementation of IEEE Std. 1547, PacifiCorp
and the New York State Public Utilities Commission. Several
others, such as Otter Tail Power, partially accept the
requirements of IEEE Std.1547 while others, independently
develop their own requirements.
The only meaningful guidelines of IEEE Std. 1547 which
seems to be universally accepted is the provision of requiring
a utility to have accessible disconnect switch at the point of
common coupling (PCC) with the utility (Fig. 1)[1]. Another
requirement which is well, although not universally, accepted
is the requirement that some type of testing (usually field
testing) (Appendix – 1 Table 4)[1]be done before the
distributed energy resource (DER) is released for operation.
An area of (wide) common concern is the (voltage) flicker
and voltage fluctuations that may be caused by a DR. IEEE
Std. 1547 states a level of acceptable voltage fluctuation
which some utilities accept while other simply makes the
blanket statement that “no abnormal voltages” will be created
by the DR. IEEE Std. 1547 also states that the DR must be
grounded in a way not to produce over voltages without
stating how this is to be done. The interconnection standards
are generally more specific on grounding and ground fault
protection issues, sometimes requiring a transfer trip to the DR
to insure no over voltages are produced.
Comparison of Some Randomly Selected Utilities
Interconnection Requirements and the Compliance with
the IEEE Std. 1547 - Interconnection Guidelines
Keith Malmedal P.E. Member, IEEE, P,K. Sen Ph.D. P.E., Senior Member, IEEE
I
C3-2
IEEE Std. 1547 contains a number of requirements to limit
harmonics created by the DR. Those interconnection
standards addressing harmonics commonly include
compliance with IEEE Std. 519 rather than referring to IEEE
Std. 1547 (Appendix I Table 3)[1].
There appears to be two areas of considerable disagreement
between the IEEE Std. 1547 and many utility interconnection
standards. The first is in the area of frequency protection.
IEEE Std. 1547 has requirements for tripping the DR at certain
abnormal frequencies within certain times (Appendix I Table
2) [1]. These requirements disagree with several of the
interconnection standards. In some cases, the interconnection
standards do not permit tripping in part of the frequency range
which IEEE Std. 1547 requires tripping. In general, where
IEEE Std. 1547 appears to be more concerned with removing
the DR from the system during an abnormal frequency event,
the utility interconnection standards seem more concerned
with keeping generation on to try to prevent an abnormal
frequency event from becoming worse due to the removal of
generation.
The second area of disagreement is the protection that must
exist at the point of common coupling (PCC). Fig. 1[1] shows
how the DR and EPS may be interconnected and illustrates
where the PCC may occur. This is an area not well addressed
in the IEEE Std. 1547 which states: “the requirements shall be
met at the point of common coupling (PCC), although the
devices used to meet these requirements can be located
elsewhere.”[1] Most utilities, however, require protective
devices to be located at the point of common coupling. Fig. 2
shows a typical distribution system including the locations
where DER may be connected. This point is commonly
protected with fuses only. However, many interconnection
requirements call for increased protection at the PCC. This is
done to prevent disturbances caused by the DR from affecting
the utility, and is often also required to insure that there is
protective relaying which backs up the relaying which may
exist at the DR.
Among the protection often required by the utility at the
PCC are over and under voltage protection, frequency
protection, ground fault protection, and occasionally some
type of backup system protection such as a 51V relay. Utility
interconnection standards often also require additional
relaying for the generator which is not required by the IEEE
Std. 1547 [2]. Some utility interconnection standards require
utility grade relays above a certain generation size, and
provisions for periodic relay testing by the utility. The
periodic re-testing of interconnection equipment is also a
requirement often seen as important by utilities, but not well
addressed in the IEEE Std. 1547[2].
III. CONCLUSION
The table in the Appendix II shows some of the more
important requirements of the IEEE Std. 1547 and compares
them with selected utility interconnection standards. It can be
seen that there is considerable variation between the standards
and the various utilities examined. Although some utilities do
accept all of IEEE Std. 1547, most of those also have other
standards which must be met. It also appears that from the
standpoint of many utilities allowing generation
interconnection the provisions of IEEE Std. 1547 are not, as
stated in the standard “universally needed” and “sufficient for
most installations” [1] and many utilities have other stringent
requirements than those stated in IEEE Std. 1547.
Fig. 1 Relationship of Interconnection Terms.
LATERAL
WITHDER
DERWITH
7979
40ELOAD
INDUSTRIAL
T3 750KVA 3Ø
12.47KV-480V
SECTIONALIZER
T1
115KV-
12.47KV
7%Z
ST115KV
SC
50
51 51G
50G
51
50
87T
51
51N
79
51G
50G 50G
51G
50
51 51
50
51G
50G
T2 30KVA 1Ø
7.2KV-120/240V
5ERES.
LOADSD1
Fig. 2 Typical Power Distribution System with Protection Shown.
The Energy Policy Act of 2005 (EPACT) specifically states
that interconnection services be based upon the IEEE Standard
1547. It also states that “agreements and procedures shall be
established whereby the services offered shall promote current
best practices of interconnection for distributed generation,
including but not limited to practices stipulated in model codes
Voltage Regulator
30/40/50
MVA
C3-3
adopted by associations of state regulatory agencies. All such
agreements and procedures shall be just and reasonable, and
not unduly discriminatory or preferential.” So EPACT
recognizes both IEEE Std. 1547 and utilities’ interconnection
practices and standards. It can be seen that in some cases the a
utility’s interconnection standards are the same as the
requirements of IEEE Std. 1547, however, in most cases there
is considerable variability between what the utility requires
and what is suggested in IEEE Std. 1547.
Some states are proposing to use IEEE Std. 1547 as the
basic standard to determine if a new DR can automatically be
connected to a system without further review or if further
study of the system is required by the utility before the DR can
be allowed to connect (which will be paid for by the
customer). The procedure might require a new DR customer
to fill out a form which would include a number of questions
about the new DR. If the answers provided proved that the
provisions of IEEE Std. 1547 were satisfied, the
interconnection of the new DR could proceed without further
study.
The basic IEEE Std. 1547 is not sufficient to determine if a
certain type of interconnection is safe for the rest of the
system. IEEE Std. 1547 mainly addresses the generator and
PCC itself, while not concerning itself with other parts of the
system or system operation.
For example, the requirement that the DR not cause over
voltages may be met at the point of common coupling (PCC),
but may not be met in other parts of the distribution system.
The customer filling out the forms may have no way of
knowing that this is true and examination of the system with
DR by a distribution engineer might be needed to determine
that this problem even existed. This problem may become
more pronounced when the DR is connected at the residential
level and every effort is made by simplifying the procedure.
Another area of concern is reclosing and the effect DR may
have on the existing utility reclosing scheme. Nearly every
distribution system in the U.S. incorporates multiple-shot
reclosing. However, how this scheme may be impacted by the
addition of DR is certainly not clear to the customer who is
designing only the equipment in the new power plant at the
PCC. IEEE Std. 1547 doesn’t address the impacts of DR on
reclosing and line sectionalizing schemes.
As long as the penetration level of DR is small (say less
than 5% of the feeder capacity) the addition of an additional
unit, especially small inverter based DR, may cause minimum
impact to the system and can be connected without further
review by the utility’s engineers. However, when DR
penetration level on a distribution system becomes sufficiently
high (presently estimated at 20% or higher) this may cause
problems with the system [3]. Will the latest DR to connect
be required to pay for all the system upgrades to make it
possible to safely connect this generator? Or will all the DR’s
on the system, old and new, be required to contribute to this
cost? This question has to be addressed. As DR penetration
levels become high the impacts become more widespread and
the IEEE Std. 1547 concentrates on impacts at the PCC and
does not address what may become widespread future effects
on both distribution and transmission systems and their
operation. These are valid questions currently imposed and
must be addressed in the future revision of the Standard.
Utilities need to be more careful in allowing
interconnections base only on the IEEE Std. 1547. It is
evident that utilities have seen the necessity of providing their
own standards, which may or may not include provisions of
IEEE Std. 1547 in the foreseeable future, to insure their
systems can continue to operate safely and reliably as DER
becomes a more important part of the generation mix.
The attempt to make a more general Standard by the IEEE
was good, but future revisions must address a number of
additional issues. Additional Std. of the 1547 series may also
include some of the questions raised by this paper.
REFERENCES
[1] IEEE Standard for Interconnecting Distributed Resources with Electric
Power Systems, IEEE Standard 1547-2003, IEEE Piscataway, NJ.
[2] K. Malmedal, P.K. Sen, and J. P. Nelson, “Application of Out-of-Step
Relaying for Small Generators in Distributed Generation,” IEEE
Transactions on Industry Applications, Vol. 41, No. 6, Nov./ Dec. 2005,
pp. 1506 – 1514.
[3] K. Malmedal, B. Kroposki, and P.K. Sen, “Distributed Energy
Resources and Renewable Energy in Distribution Systems: Protection
Considerations and Penetration Levels,” (In Review), 2008 IEEE
Industry Applications Society 43rd Annual Meeting, Edmonton, Alberta,
October 5-9, 2008.
[4] IEEE Standard Conformance Test Procedures for Equipment
Interconnecting Distributed Resources with Electric Power Systems,
IEEE 1547.1, IEEE, Piscataway, NJ.
[5] XCEL Energy Interconnection Guidelines for Transmission
Interconnected Producer-Owned Generation 20MW and less. Version 1,
Xcel Energy, June 15, 2006.
[6] PacifiCorp Cogeneration and Parallel Generation Interconnection
Guide,
www.puc.state.or.us/PUC/admin_rules/workshops/interconnection/drpac
ificorp/pplengin.pdf
[7] AESO Generation and Load Interconnection Standard,
www.aeso.ca/rulesprocedures/9056.html.
[8] Otter Tail Power Company, Guidelines for Generation, Tie-Line, and
Substation Interconnection,
www.otpco.com/NewsInformation/GeneratorInterconnect.asp
[9] Rules for Interconnecting Distributed Generation Systems, Wisconsin
Public Service Commission PSC 119,
www.legis.state.wi.us/rsb/code/psc/psc119.pdf
[10] Distributed Generation Interconnection Manual, Public Utility
Commission of Texas
www.puc.state.tx.us/electric/business/dg/dgmanual.pdf May 1, 2002.
[11] Guidelines for Interconnection of Customer Generators, City of
Anaheim Public Utilities Department, Electrical Engineering,
www.anaheim.net/utilities/adv_svc_prog/com_pol/Comm%20Guideline
s2-1.pdf, December 2005.
[12] New York State Standardized Interconnection Requirements and
Application Process for New Distributed Generators 2 MW or Less
Connected in Parallel with Utility Distribution Systems, New York
State, Public Service Commission,
www.dps.state.ny.us/94e0952_11152000.pdf , September 2005.
[13] SRP Interconnection Guidelines for Distributed Generators,
www.srpnet.com/electric/pdfx/gen_guidelines.pdf, December 2002.
[14] Application Guide for Distributed Generation Interconnection: 2006
Update, The NRECA Guide to IEEE 1547, Resource Dynamics
Corporation,
www.nreca.org/Documents/PublicPolicy/DGApplicationGuide-
Final.pdf, March 2006.
[15] K. Malmedal, B. Kroposki, and P. K. Sen, “The Energy Policy Act of
2005 and its Impact on Distributed Generation,” IEEE IAS Magazine,
January 2007, pp. 14-20.
[16] K. Malmedal, B. Kroposki, and P.K. Sen, “The Energy Policy Act of
2005 and it’s Impact on Renewable Energy Applications in the USA”,
2007 IEEE Power Engineering Society General Meeting Conference
Record, Annual Summer Meeting, Tampa Bay, Florida, June 2007.
[17] Energy Policy Act of 2005, Washington, DC, 2005.
C3-4
Keith Malmedal (Member, IEEE) received his BSEET degree from
Metropolitan State College of Denver in 1995, a MSEE degree (Power) and a
MSCE degree (Structures) from the University of
Colorado at Denver in 1998 and 2002, respectively.
Keith is presently a PhD candidate at Colorado School
of Mines in Engineering Systems (Electrical
Specialty). He has over sixteen years combined
experience in electrical power system analyses and
system study, teaching and research and is presently
the President and a senior project manager at NEI
Electric Power Engineering, Arvada, Colorado,
specializing in all aspects of power system design.
Keith has published over a dozen technical papers in
archival journals and conference proceedings and
taught (and co-taught) regular university courses, short courses on a variety of
subjects related to the interrelated areas of power systems, machines,
protections, renewable energy applications, and energy policy issues to
hundreds of practicing professionals. Mr. Malmedal is a member of the
American Society of Civil Engineers and a registered professional engineer in
14 states.
Pankaj K. (PK) Sen (Sr. Member, IEEE) received his
BSEE degree (with honors) (1966) from Jadavpur
University, India, and the M.Eng. (1971) and Ph.D.
(1974) degrees in electrical engineering from the
Technical University of Nova Scotia (Dalhousie
University), Halifax, NS, Canada. He is currently a
Professor of Engineering and Site Director of the Power
Systems Engineering Research Center (www.pserc.org)
at Colorado School of Mines in Golden, Colorado. His
research interests include application problems in
electric machines, power systems, protection, renewable energy and
distributed generation and power engineering education. He has published
more than 130 articles in various archival journals and conference proceedings
and has supervised over 120 students with MS and PhD degrees. Dr. Sen
taught a number of regular advanced level graduate and many undergraduate
university courses, and conducted workshops and taught short courses on
machines, power systems, transmission and distribution, renewable energy,
energy policy and energy economics to literally thousands of practicing
engineers and is a registered professional engineer in the State of Colorado.
APPENDIX I
Selected Sketches from the IEEE Std. 1547[1]
Fig. 3 Schematic of Interconnection.
TABLE 1
Interconnection System Response to Abnormal Voltages.
TABLE 2
Interconnection System Response to Abnormal Frequencies.
TABLE 3
Maximum Harmonic Current Distortion in Percent of Current.
TABLE 4
Sequence for Conducting Design Test.
TABLE 5
Synchronization Parameter Limits for Synchronous Interconnection to an EPS
or an Energized Local EPS to an Energized Area EPS.
TABLE 6
Maximum Harmonic Distortion in Percent of Rated Voltage for Synchronous
Machines.
AP
PE
ND
IX I
I
TA
BL
E 7
Co
mp
aris
on
of
Uti
lity
Req
uir
emen
ts w
ith
IE
EE
Std
. N
o.
15
47
Req
uir
em
en
t IE
EE
15
47
XC
EL
Inte
rco
nn
ecti
on
Sta
nd
ard
fo
r
<2
0M
W
Pa
cif
iCo
rp
A
lberta
Ele
ctr
ic
Ott
er T
ail
Po
wer
Wis
co
nsi
n
PU
C
Tex
as
PU
C
Cit
y o
f
An
ah
eim
New
Yo
rk
Sta
te P
UC
Sa
lt
Riv
er
Pro
ject
Mu
st C
om
ply
wit
h I
EE
E 1
54
7
n
o
yes
no
F
lick
er
req
uir
emen
ts
on
ly
Fo
r p
aral
lel-
ing
eq
uip
men
t
on
ly
no
n
o
yes
no
(DR
) sh
all
no
t re
gu
late
vo
ltag
e at
(P
CC
) (4
.1.1
)
yes
Vo
ltag
e
Reg
ula
tio
n m
ay
be
allo
wed
n
o
no
Gen
era
tio
n m
ust
con
tro
l li
ne-
gro
und
vo
ltag
e if
isl
and
ed
no
y
es
no
n
o
yes
Gro
un
din
g s
chem
e sh
all
no
t cau
se o
ver
vo
ltag
es
or
dis
rup
t g
rou
nd
fau
lt p
rote
cti
on
.
(4.1
.2)
yes
Mu
st b
e
eff
ecti
vely
gro
und
ed
no
Mu
st b
e
eff
ecti
vely
gro
und
ed
Gen
era
tio
n m
ust
con
tro
l li
ne-
gro
und
vo
ltag
e if
isl
and
ed
and
sev
eral
sch
emes
may
be u
sed
to
pre
ven
t o
ver
vo
ltag
es
Iso
lati
on
Tra
ns.
may
be
req
uir
ed
no
y
es
no
n
o
DR
sh
all
para
llel
wit
h E
PS
wit
ho
ut
cau
sin
g v
olt
age
flu
ctu
atio
n g
reat
er t
han
5%
.
(4.1
.3)
yes
no
n
o
no
y
es
yes
no
y
es
no
n
o
Net
wo
rk p
rote
cto
rs s
hall
no
t b
e u
sed
to
iso
late
a n
etw
ork
to
wh
ich
DR
is
co
nn
ecte
d u
nle
ss p
rote
cto
rs a
re t
este
d a
nd
rate
d f
or
the
pu
rpo
se.
(4.1
.4.2
)
yes
no
no
no
no
no
no
no
no
no
DR
sh
all
no
t p
rev
en
t th
e r
eclo
sin
g o
f an
y
netw
ork
pro
tecto
rs a
nd
sh
all
no
t re
qu
ire
ch
an
ges
in
pro
tecto
r cle
ari
ng
tim
es.
(4.1
.4.2
)
yes
no
no
no
no
no
no
no
no
no
DR
sh
all
no
t cau
se c
ycli
ng
of
netw
ork
pro
tecto
rs.
(4.1
.4.2
)
yes
no
no
no
no
no
no
no
no
no
Net
wo
rk l
oad
ing
and
fau
lt i
nte
rru
pti
ng
cap
acit
y s
hall
no
t b
e e
xce
ed
ed w
ith
th
e
add
itio
n o
f D
R.
(4.1
.4.2
)
yes
no
no
no
no
no
no
no
no
no
DR
sh
all
no
t en
erg
ize t
he E
PS
wh
en
th
e
EP
S i
s d
e-e
nerg
ized
.
(4.1
.5)
yes
no
n
o
no
n
o
no
n
o
no
n
o
no
DR
<2
50
kV
A a
t th
e P
CC
sh
all
mo
nit
or
real
an
d r
eacti
ve p
ow
er,
an
d v
olt
age a
t it
s
PC
C
.
(4.1
.6)
yes
yes
no
n
o
no
n
o
no
n
o
no
n
o
C3-5
Req
uir
em
en
t IE
EE
15
47
XC
EL
Inte
rco
nn
ecti
on
Sta
nd
ard
fo
r
<2
0M
W
Pa
cif
iCo
rp
A
lberta
Ele
ctr
ic
Ott
er T
ail
Po
wer
Wis
co
nsi
n
PU
C
Tex
as
PU
C
Cit
y o
f
An
ah
eim
New
Yo
rk
Sta
te P
UC
Sa
lt R
iver
Pro
ject
Inte
rco
nnec
tio
n s
yst
em s
hal
l w
ith
stan
d
EM
I an
d E
MI
shall
no
t cau
se
mis
op
era
tio
n.
(4.1
.8.1
)
yes
no
no
no
no
no
no
no
no
no
Inte
rco
nnec
tio
n s
yst
em s
hal
l w
ith
stan
d
vo
ltag
e an
d c
urr
ent
surg
es p
er I
EE
E
C6
2.4
1.2
-200
2 o
r C
37
.90
.1-2
002
(4.1
.8.2
)
yes
no
no
no
yes
no
no
no
no
no
Par
alle
lin
g d
ev
ice s
hall
wit
hst
an
d 2
20
% o
f
inte
rco
nn
ecte
d s
yst
em r
ated
vo
ltag
e.
(4.1
.8.3
)
yes
no
no
no
no
no
no
no
no
no
DR
sh
all
no
t en
erg
ize f
ault
s o
n t
he E
PS
circ
uit
to
wh
ich
it
is c
on
nec
ted
.
(4.2
.1)
yes
yes
no
n
o
no
y
es
yes
yes
no
n
o
DR
sh
all
de-e
nerg
ize t
he E
PS
pri
or
to a
ny
reclo
sure
on
th
e E
PS
.
(4.2
.2)
yes
no
n
o
no
y
es
no
y
es
yes
no
n
o
DR
pro
tect
ion
sy
stem
sh
all
det
ect
vo
ltag
es
at t
erm
inal
s if
DR
<3
0k
W, in
terc
on
nec
tio
n
eq
uip
men
t is
cert
ifie
d t
o p
ass
a n
on
-
isla
nd
ing
tes
t, o
r D
R i
s le
ss t
han
50
% o
f
local
EP
S m
inim
um
dem
and
an
d e
xp
ort
of
po
wer
is
no
t p
erm
itte
d.
(4.2
.3)
yes
no
no
no
no
no
no
no
no
no
Sh
all
trip
in
0.1
6 s
ec i
f V
<5
0%
, (4
.2.3
)
yes
no
1-5
sec
no
no
no
yes
no
Yes
n
o
Sh
all
trip
in
2
.00
sec
if
50
%<
V<
88
%,
(4.2
.3)
yes
no
1-5
sec
no
no
no
yes
no
Yes
n
o
Sh
all
tri
p i
n 1
sec i
f 1
10
%<
V<
12
0%
, (4
.2.3
)
yes
no
1-5
sec
no
no
no
yes
;
3
0
cy
at
10
5%
n
oY
es
no
Sh
all
tri
p i
n 0
.16
sec i
f V
>1
20
%
(4.2
.3)
yes
no
no
no
no
no
yes
no
Yes
n
o
Fre
q t
rip
set
tin
gs
shal
l b
e ad
just
able
fo
r
ov
er
30
kW
(4.2
.4)
yes
yes
no
no
no
no
no
no
no
no
Sh
all
trip
in
0.1
6 s
ec i
f F
>6
0.5
Hz
(4.2
.4)
yes
Tri
pp
ing
no
t
per
mit
ted
bel
ow
60
.5 H
z
10
cy
cle
s
ab
ov
e 6
1
Hz
Tri
pp
ing
no
t
per
mit
ted
belo
w 6
0.6
Hz.
3 m
in. ab
ov
e
60
.6H
z, 3
0
secs.
ab
ov
e
61
.6 H
z
Tri
pp
ing
no
t
per
mit
ted
bel
ow
60
.5 H
z
no
0.2
5 s
ec
no
Yes
n
o
Sh
all
trip
in
0.1
6 s
ec i
f F
<5
9.3
Hz
(4.2
.4)
yes
Tri
pp
ing
no
t
per
mit
ted
6 c
ycle
s
belo
w 5
9
Hz
3 m
inu
tes;
30
secs.
belo
w
58
.4H
z; 7
.5
secs.
belo
w
57
.8H
z; 4
5
cy
cle
s b
elo
w
57
.3 H
z
Tri
pp
ing
no
t
per
mit
ted
ab
ov
e
59
.5 H
z
no
0.2
5 s
ec
no
Yes
n
o
C3-6
Req
uir
em
en
t IE
EE
15
47
XC
EL
Inte
rco
nn
ecti
on
Sta
nd
ard
fo
r
<2
0M
W
Pa
cif
iCo
rp
A
lberta
Ele
ctr
ic
Ott
er T
ail
Po
wer
Wis
co
nsi
n
PU
C
Tex
as
PU
C
Cit
y o
f
An
ah
eim
New
Yo
rk
Sta
te P
UC
Sa
lt R
iver
Pro
ject
If D
R>
30
kW
sh
all
hav
e ad
just
able
tri
p s
et
po
int
for
F<
59
.8 t
o 5
7 H
z an
d a
dju
st
betw
een
0.1
6 a
nd
300
sec
(4.2
.4)
yes
Tri
pp
ing
per
mit
ted
bel
ow
58
.5 H
z.
no
Tri
pp
ing
no
t
per
mit
ted
ab
ov
e
59
.4 H
z
no
no
no
no
Yes
n
o
No
DR
rec
on
nec
tio
n s
hal
l o
ccu
r if
vo
ltag
e
an
d f
req
uen
cy
are
ou
t o
f ra
ng
e.
(4.2
.6)
yes
no
no
no
no
no
yes
no
no
no
DR
sh
all
hav
e ad
just
able
tim
e d
elay
or
a
dela
y o
f 5
min
ute
s b
efo
re r
eco
nnecti
on
.
(4.2
.6)
yes
no
no
no
no
no
no
no
no
no
DR
sh
all
no
t in
ject
mo
re D
C c
urr
ent
than
0.5
% o
f it
s ra
ted
ou
tpu
t.
(4.3
.1)
yes
no
n
o
no
n
o
no
n
o
no
n
o
no
DR
sh
all
no
t p
rod
uce
ob
ject
ionab
le f
lick
er(4
.3.2
)
yes
yes
no
y
es
yes
yes
no
y
es
no
n
o
Sh
all
no
t p
rod
uce m
ore
th
an
4%
harm
on
ic
belo
w t
he 1
1th
.
(4.3
.3)
yes
<1
% b
elo
w t
he
7th
n
on
oIE
EE
51
9
no
no
no
no
Sh
all
no
t p
rod
uce
mo
re t
han
2%
harm
on
ics
betw
een
11
th a
nd
17
th.
(4.3
.3)
yes
IEE
E 5
19
n
oIE
EE
51
9
IEE
E 5
19
n
oIE
EE
51
9
no
IEE
E 5
19
n
o
Sh
all
no
t p
rod
uce
mo
re t
han
1.5
%
harm
on
ics
betw
een
17
th a
nd
23
rd.
(4.3
.3)
yes
IEE
E 5
19
n
oIE
EE
51
9
IEE
E 5
19
n
oIE
EE
51
9
no
IEE
E 5
19
n
o
Sh
all
no
t p
rod
uce
mo
re t
han
0.6
%
harm
on
ics
betw
een
23
rd a
nd
35
th.
(4.3
.3)
yes
IEE
E 5
19
n
oIE
EE
51
9
IEE
E 5
19
n
oIE
EE
51
9
no
IEE
E 5
19
n
o
Sh
all
no
t p
rod
uce
mo
re t
han
0.3
%
har
mo
nic
s g
reat
er t
han
th
e 3
5th
.
(4.3
.3)
yes
IEE
E 5
19
n
oIE
EE
51
9
IEE
E 5
19
n
oIE
EE
51
9
no
IEE
E 5
19
n
o
To
tal
harm
on
ic d
isto
rtio
n s
hall
no
t ex
ceed
5%
(4.3
.3)
yes
IEE
E 5
19
n
oIE
EE
51
9
IEE
E 5
19
n
oIE
EE
51
9
no
IEE
E 5
19
n
o
DR
sh
all
dete
ct
an
d d
e-e
nrg
ize a
n i
slan
d.
(4.4
.1.)
yes
no
n
o
no
If i
slan
din
g i
s
po
ssib
le S
CA
DA
is r
equ
ired
yes
no
y
es
yes
yes
DR
sh
all
un
derg
o t
esti
ng
at
facto
ry o
r in
fiel
d.
(5.1
)
yes
yes
no
n
o
yes
yes
yes
yes
no
y
es
C3-7
Req
uir
em
en
t IE
EE
15
47
XC
EL
Inte
rco
nn
ecti
on
Sta
nd
ard
fo
r
<2
0M
W
Pa
cif
iCo
rp
A
lberta
Ele
ctr
ic
Ott
er T
ail
Po
wer
Wis
co
nsi
n
PU
C
Tex
as
PU
C
Cit
y o
f
An
ah
eim
New
Yo
rk
Sta
te P
UC
Sa
lt R
iver
Pro
ject
Go
vern
or
mu
st o
pera
te b
etw
een
59
.5 a
nd
60
.5 H
Z a
nd
be a
dju
stab
le 0
-10
% d
roo
p.
no
y
es
no
n
o
no
n
o
no
n
o
no
n
o
Mu
st h
av
e C
ircu
it b
reak
er
at
PC
C
no
y
es
no
n
o
no
y
es
Fo
r sy
nch
.
mach
. n
o
no
n
o
25
rel
ay r
equ
ired
n
o
yes
no
n
o
yes
yes
yes
ab
ov
e
1M
W
no
n
o
59
rel
ay r
equ
ired
n
o
yes
no
n
o
yes
yes
yes
yes
yes
ab
ov
e
50
kW
27
rel
ay r
equ
ired
n
o
yes
no
n
o
yes
yes
yes
yes
yes
Yes
81
rel
ay r
equ
ired
n
o
yes
no
n
o
yes
yes
yes
yes
yes
ab
ov
e
50
kW
51
N r
elay
req
uir
ed
no
y
es
no
n
o
yes
yes
may
be
req
uir
ed
ab
ov
e
1M
W
no
May
be
req
uir
ed
51
V o
r 2
1 r
elay
req
uir
ed
no
n
o
no
n
o
yes
yes
no
ab
ov
e
1M
W
no
n
o
32
rel
ay r
equ
ired
n
o
yes
no
n
o
yes
no
m
ay b
e
req
uir
ed
no
n
o
no
47
rel
ay r
equ
ired
n
o
no
n
o
no
n
o
no
n
o
yes
no
n
o
15
rel
ay r
equ
ired
fo
r in
du
ctio
n m
ach
ines
n
o
yes
no
n
o
no
n
o
no
n
o
no
n
o
Sy
stem
Stu
dy
Req
uir
ed
no
n
o
yes
no
Info
rmat
ion
mu
st
be a
vail
able
fo
r
un
its
ab
ov
e 5
MW
yes
may
be
req
uir
ed
no
n
o
no
Mu
st n
ot
incre
ase
vo
ltag
e u
nbala
nce b
y
mo
re t
han
1%
n
o
no
n
o
yes
no
n
o
no
n
o
no
n
o
Uti
lity
gra
de
rela
ys
req
uir
ed
no
y
es
no
n
o
yes
ab
ove 1
00k
W
no
n
o
no
n
o
ab
ov
e
30
0k
W
Sy
stem
mu
st b
e U
L l
iste
d
no
n
o
no
n
o
no
in
terr
up
tin
g
dev
ice
no
n
o
UL
17
41
Dis
con
nect
Sw
itch
an
d
inte
rru
pti
ng
dev
ices
Mu
st p
rov
ide
test
sw
itch
es f
or
pro
tect
ion
test
ing
n
o
no
n
o
no
n
o
yes
no
n
o
no
n
o
C3-8