TELKOM
NIKA
, Vol.13, No
.1, March 2
0
1
5
, pp. 21~3
1
ISSN: 1693-6
930,
accredited
A
by DIKTI, De
cree No: 58/DIK
T
I/Kep/2013
DOI
:
10.12928/TELKOMNIKA.v13i1.960
21
Re
cei
v
ed O
c
t
ober 7, 20
14;
Revi
se
d Ja
n
uary 4, 2015;
Acce
pt
ed Jan
uary 16, 201
5
Unbalanced Active Distribution Analysis with
Renewable Distributed Energy Resources
Sy
afi
i
1*
, K.M. Nor
2
1
Electrical En
gi
neer
ing D
e
p
a
rtment, Andal
as
Univers
i
t
y
, Pa
d
ang, Ind
ones
ia
2
Electrical En
gi
neer
ing F
a
c
u
lty, Univ
ersiti
T
e
knol
ogi Ma
la
ys
ia, Johor Ba
har
u, Mala
ysi
a
*Corres
p
o
ndi
n
g
author, e-ma
i
l
: s
y
afii
@ft.una
nd.ac.id
A
b
st
r
a
ct
This pap
er pre
s
ents un
bal
an
ced active
dist
ribut
i
on syste
m
a
nalys
is w
i
th renew
a
b
le d
i
stribute
d
Energy
Reso
ur
ces (DER). T
h
e ren
e
w
abl
e D
E
R mod
e
ls
h
a
v
e be
en c
onsi
dere
d
are
ph
ot
ovolta
ic (PV) a
n
d
W
i
nd T
u
r
b
in
e
gen
eratio
n (W
T
G
). T
he three
-
phas
e d
i
stri
b
u
t
ion
loa
d
fl
ow
on th
e
basis
o
f
the sy
mmetri
ca
l
compo
nents
h
a
s be
en
use
d
i
n
the
an
alysis.
The u
n
b
a
la
nc
ed activ
e
distri
butio
n syste
m
has b
e
e
n
a
n
a
l
i
z
e
d
usin
g IEEE 13
nod
e fee
der
and IEEE
85
0
0
no
de fe
ed
er
w
i
th renew
ab
l
e
DER
units.
The center-ta
p
ped
(CT
)
transformer loa
d
mo
de
l has be
en inc
l
u
ded i
n
progr
a
m
. T
he variati
o
n of w
i
nd spee
d (m/s) for W
T
G,
solar
rad
i
atio
n
(W
/m²) an
d te
mp
eratur
e (°C)
for PV
hav
e b
een
si
mu
late
d. T
he s
i
mul
a
tio
n
res
u
lts sh
ow
tha
t
the prop
osed
DER mode
l can be us
ed to
analysis re
ne
w
able DER i
m
pacts in un
bal
ance
d
distrib
u
tio
n
system. The
i
n
tegrati
on
of r
enew
ab
le
DE
R un
its i
n
to
a
n
existi
ng
distr
i
buti
on
netw
o
r
k
can
i
m
pr
ove
the
voltag
e profil
e and re
duc
e total system l
o
ss
es.
The simu
la
tion resu
lts show
that DERs si
z
e
an
d locati
o
n
are i
m
p
o
rtant factors to impro
v
e volt
ag
e profi
l
e an
d lin
e loss
reductio
n
.
Ke
y
w
ords
: di
stributed e
ner
gy resourc
e
s, photov
oltaic,
w
i
nd turbin
e, active distrib
u
tion syste
m
a
n
d
unb
ala
n
ce
d lo
a
d
flow
1. Introduc
tion
Risi
ng pu
blic
awa
r
en
ess fo
r enviro
n
me
ntal prot
e
c
tion,
increa
sing fu
el pri
c
e an
d
energy
con
s
um
ption,
have create
d
intere
st in gree
n (rene
wable) p
o
wer
gene
ration
systems [1]. The
developm
ent
of renewa
b
le-e
ne
rgy reso
urce
s
ha
s be
come i
n
crea
singly
attractive and
comp
etitive and economi
c
ally feasib
le. These facts h
a
ve led towa
rds the in
cre
a
s
e pe
netratio
n
of
distrib
u
ted e
nergy
re
sou
r
ce
s (DER) u
s
ing
ren
e
wa
ble-e
n
e
r
gy source
s into t
he ele
c
tri
c
al
grid.
Distri
buted e
nergy resource
s
(DE
R
), i
n
clu
d
ing di
stributed g
ene
ration (DG
)
and di
stribut
e
d
stora
ge
(DS), are
so
urce
s of
ene
rgy l
o
cate
d in
the
distri
bution
netwo
rks th
a
t
can
provide
a
variety of ben
efits, inclu
d
in
g improved
reliabilit
y
and redu
ce
tran
smissi
on and distrib
u
tion
lo
sse
s
[2].
Distri
buted gene
ration usin
g
re
newable-ene
rg
y
sou
r
ces,
su
ch a
s
wi
nd, sola
r
photovoltai
c
and hyd
r
o p
o
w
er
ha
s rece
ived co
nsi
der
able attentio
n
in re
cent ye
ars.
Dist
ribut
ed
stora
ge is
an
integral pa
rt of a hybrid re
new
able
-
en
ergy powe
r
gen
eration
syste
m
[3]. Different
rene
wa
ble-en
ergy po
we
r g
eneration te
chnolo
g
ies
u
s
e
different en
ergy stora
ge scheme
s
, whi
c
h
may be u
s
ed
in hybrid
syst
ems.
Rene
wable-ene
rgy t
e
ch
nolo
g
ies
and its
ene
rg
y storag
e can
be
use
d
b
a
ttery for
sola
r PV
and
biom
ass, flywhe
el f
o
r mi
ni a
nd
micro hyd
r
o,
su
perco
ndu
cting
magneti
c
ene
rgy
stora
g
e
(SMES) for wi
nd tu
rbine
a
n
d
supe
rcapa
citor for fuel
cell.
Simulations
sho
w
that th
e
pro
p
o
s
ed
en
ergy
stora
ge system ca
n meet
the r
eal
-time po
we
r d
e
mand
and
save
money [4].
2. Unbalan
c
ed Ac
tiv
e
Distribu
tion Analy
s
is
The DE
R inst
allation
s ha
s cha
nge
d distributi
on sy
ste
m
s from a p
a
ssive
system
to be an
active net
work [5]. The po
wer
gen
erati
ons
are
built in are
a
s
with
sufficie
n
t co
oling water
a
n
d
whe
r
e fu
el
su
pply ro
utes are availabl
e. T
herefo
r
e,
in
the p
r
eviou
s
p
o
we
r
system operation,
mo
st
power g
ene
rations a
r
e lo
cated at
spe
c
ific remote
sites a
nd a
r
e con
n
e
c
ted
to an extended
transmissio
n grid whi
c
h
tra
n
sfers
b
u
lk el
ectri
c
al
p
o
we
r to the di
stri
bution g
r
id
s. The di
strib
u
tion
grid ta
ke
s
pa
rt of the
tran
smitted p
o
we
r an
d
se
rves the
con
n
e
c
ted lo
ad
s. Thi
s
way of
po
we
r
Evaluation Warning : The document was created with Spire.PDF for Python.
ISSN: 16
93-6
930
TELKOM
NIKA
Vol. 13, No. 1, March 2
015 : 21 – 31
22
system operation is often calle
d a ‘vertically-operate
d power sy
stem’ [6] illustrated in Figure 1
(a).
The future power
system
grid
will
hav
e been increasing im
pl
em
entation of
di
stributed
energy re
sou
r
ce
s. The
DER are mai
n
l
y
conne
cted
to the distrib
u
tion grid. T
he integratio
n o
f
distrib
u
ted g
enerators in
power sy
ste
m
s may cau
s
e a tran
siti
o
n
from the current ‘vertically-
operated po
wer
system’, whi
c
h is sup
ported m
a
in
l
y
by several large
centrali
zed
synchro
n
ous
gene
rato
rs, i
n
to a future
‘hori
z
ontally-operated p
o
w
er
syste
m
’, with large n
u
mbe
r
di
strib
u
ted
energy re
sou
r
ce
s.
(a)
Powe
r flow wi
thout DER Int
egratio
n
(b)
Powe
r Flow
with DER inte
gration
Figure 1. Impact of DE
R Integratio
n in power sy
ste
m
grid
Powe
r
Generation
HV Tr
ansmission
Netw
ork
Powe
r
Generation
MV/LV Distribu
tion
Network
MV/LV Distribu
tion
Network
Load C
e
nter
Load C
e
nter
MV/LV Distribu
tion
Network
DER Units
DER Units
Powe
r
Generation
HV Tr
ansmission
Netw
ork
Powe
r
Generation
MV/LV Distribu
tion
Network
Load C
e
nter
Load C
e
nter
Evaluation Warning : The document was created with Spire.PDF for Python.
TELKOM
NIKA
ISSN:
1693-6
930
Unb
a
lan
c
ed
Active
Distri
b
u
tion Analysi
s
with R
ene
wable Di
strib
u
ted Ener
gy Re
sou
r
c
e
s (S
yaf
ii)
23
The implem
e
n
tation of DER in the distri
bution gr
i
d
cl
ose
r
to the load whi
c
h
will affect the
local p
o
wer flow [7]. The increa
sing p
e
netration le
ve
l of DER is e
x
pected a
nd
the total amo
unt
of generated
electri
c
po
wer can exce
ed the to
tal con
n
e
c
ted lo
ad. As a co
nse
que
nce the
distrib
u
tion g
r
id can sta
r
t
exporting el
ectri
c
po
we
r to neighbo
uring di
stri
bu
tion grid
s what
conve
r
ts
th
e power syste
m
into
a
ho
ri
zontally op
erat
ed p
o
wer
syst
em. This is shown in
Figu
re 1
(b).
2.1. Rene
w
a
ble DER Mo
del
Figure 2 Obje
ct-O
riente
d
Powe
r Sy
stem
Model Incl
udi
ng DER M
o
d
e
l
The o
b
je
ct o
r
iented
p
r
og
ramming
ha
s bee
n u
s
ed
in this re
se
a
r
ch. By
usi
n
g obj
ect
oriente
d
p
r
og
rammin
g
, up
dating o
r
a
d
d
ing n
e
w
alg
o
rithm
can
b
e
don
e to an
y spe
c
ific o
b
j
e
ct
without affect
ing or e
s
cala
ting the modi
ficati
on to other obj
ect in
side the software. The DER
model
s have been
devel
op
ed
u
s
in
g
the
state-of
-the a
r
t of o
b
je
ct
co
mpone
nt b
a
sed a
p
p
r
oa
ch,
so
the mod
e
ls can b
e
integ
r
a
t
ed with
exist
i
ng o
b
je
ct
co
mpone
nt software p
r
eviou
s
ly devel
ope
d i
n
[8].
The ne
w
cla
s
s library t
o
mo
del
DER ha
s b
een
ad
ded i
n
o
b
je
ct
oriente
d
p
o
wer
system
mo
de
l
[8] using visu
al C++ p
r
og
ramming. Th
e
extended
cla
s
ses fo
r DE
R model follo
w the model in
[9
]
as sh
own
in
Figu
re 2.
T
he DER are
gene
rally
mo
delled
as PV or P
Q
n
ode
s in
po
we
r fl
ow
studie
s
for u
nbala
n
ced a
c
tive distributi
on syst
e
m
. Ho
wever, the
spe
c
ified P,Q and V values
depe
nd on th
e type of DER.
2.2. Impact of RDE
R in po
w
e
r
s
y
stem opera
tion
Larg
e
-scale
i
n
tegratio
n of
DG
in
dist
ri
but
ion grid
s can
have
a signifi
cant
im
pact on
power syste
m
ope
ration. Therefor
e, m
any
re
se
arch
proj
ect
s
a
r
e defined and
nume
r
ou
s stu
d
ies
on integratio
n issue
s
of DER are
carrie
d out. Fo
r in
stan
ce, the e
ffect of DG on voltage pro
f
ile
studie
d
in [10]-[11], and system losse
s
studied in
[1
2]. In general
, it is nece
s
sary to kee
p
th
e
voltage of a
tran
smi
ssio
n
or dist
ribut
ion g
r
id
withi
n
sp
ecifie
d li
mits for
all
possibl
e loa
d
i
ng
con
d
it
ion
s
an
d minimiz
e
sy
st
em lo
sse
s.
Incre
a
si
ng th
e numb
e
r of
DER u
n
its in
a local
di
stri
b
u
tion gri
d
ca
n
lead to a violation of
the allo
wabl
e
voltage level
due to
volta
ge ri
se,
distu
r
b the
cl
assi
cal way
of vol
t
age
control
or
deterio
rate th
e po
wer
quali
t
y. In this referen
c
e [1
1] h
a
s b
een di
scussed
and q
uantified voltage
Evaluation Warning : The document was created with Spire.PDF for Python.
ISSN: 16
93-6
930
TELKOM
NIKA
Vol. 13, No. 1, March 2
015 : 21 – 31
24
profile imp
r
ov
ement for a simple ca
se of
dist
ribute
d
wind turbin
e generation. Simulation re
su
lts
clea
rly show that distri
bu
t
ed gen
eratio
ns
can i
m
prove voltage
profile
at a l
oad p
o
int. T
h
e
distrib
u
tion g
r
id with ca
ble
s
, the X/R ratio is less
tha
n
1. This mea
n
s that the re
sista
n
ce ca
n
not
be ne
gle
c
ted
anymore, an
d hen
ce
the v
o
ltage d
r
o
p
d
epen
ds
on
active and
rea
c
t
i
ve power [1
3
]
.
Cabl
es
with a
small cond
u
c
tor
size hav
e a X/R
ratio
betwe
en 0.25
and 0.5 an
d for these ca
bl
es,
the voltage drop domin
antl
y
depend
s on
active power [13].
Installing
DE
R units
along
powe
r
di
strib
u
ti
on feede
rs may effect on
voltage stabi
lity due
to exce
ssive
active an
d re
active po
we
r
injectio
n [10]. The voltag
e l
e
vel in a
distribution n
e
two
r
k
must b
e
kept
within
a cert
ain rang
e, as power
syste
m
and
cu
sto
m
er e
quip
m
e
n
t function
s
o
n
ly
prop
erly if the voltage is maintaine
d
within th
is ran
g
e
.
The voltage range for no
rmal operation
is
defined
within
±10% ba
sed
on IEC 6100
0
-
2-
2 stan
dard
for low voltage level [14].
The im
pa
ct
of DG
on
sy
stem lo
sse
s
stron
g
ly de
p
end
s o
n
the
inje
cted
po
wer an
d
locatio
n
of
DG in th
e di
stri
bution
network. Mo
reov
e
r
, i
n
termittent g
e
neratio
n
sou
r
ce
s
with a
we
ak
correl
ation
wi
th the loa
d
, such
as wi
nd t
u
rbin
es, ca
n have
a neg
ative
impa
ct
on system
l
o
sse
s
.
Espe
cially d
u
r
ing
the
night-time there i
s
l
o
w
dem
and
a
nd in
a
hig
h
wind
situ
ation
,
the di
strib
u
tion
grid
can
sta
r
t to export p
o
we
r which i
n
crea
se
s
the line losses.
In this case, local
storage
system
s
can
have a
po
sitive effect on t
he line l
o
sse
s
be
ca
use th
e sto
r
ag
e sy
stem
can l
o
cally
balan
ce th
e p
o
we
r flo
w
an
d prevents th
e expo
rt of p
o
we
r. In [12] i
t
is de
mon
s
trated that the
grid
losse
s
incre
a
s
e for
remote
ly conne
cted
wind tu
rbin
e
s
. It is also de
monst
r
ated th
at wind turbin
es
con
n
e
c
ted su
fficiently close to the load have a po
sitive effect on gri
d
losse
s
.
3. Descrip
tio
n
of the T
est Sy
stem
The impa
ct o
f
RDER in u
nbala
n
ced di
stri
butio
n system simulate
d and analy
z
ed usi
ng
standard IEEE data 13 no
de and 8500
node feeder.
3.1. IEEE data 13 node test feeder.
Radi
al distri
b
u
tion netwo
rk IEEE 13 nod
e te
st feeder
use
d
to simul
a
te and analy
z
e the
impact
of RDER in unbal
anced di
st
ribution sy
stem. T
he IEEE 13 t
e
st
feeder
contai
ns the m
o
st
comm
on fe
ature
s
in
a
dist
ribution
net
work
su
ch a
s
:
singl
e-p
h
a
s
e,
two
-
pha
se,
and th
ree
-
p
h
a
se
power
syste
m
element
s for line
s
an
d
transfo
rme
r
s
and un
bala
n
c
ed lo
ad al
so pre
s
e
n
t in this
system. Fo
r unbal
anced
distrib
u
tion
system
sim
u
lation an
d
anylisi
s
carry out two case
s
system.The first sy
stem is a modified IEEE 13
node feeder with t
w
o unit
s
of photovoltaic
DG
con
n
e
c
ted
at nod
e ID 63
4
and
no
de I
D
672
a
s
sho
w
n i
n
Fi
gure
3a. Th
e
se
co
nd
system
is a
modified IEEE 13 node feeder
with two units of
WTG DG connected at
node
ID 634 and node
ID 672 a
s
sh
own in Fig
u
re
3b.
The KC200
G
T
sola
r a
rray
data [15] ha
ve been u
s
e
d
in the un
b
a
lan
c
ed the
r
e-ph
ase
power flo
w
si
mulation. By
assumin
g
, nu
mber of
a
rray
s
e
qual to
10
use
d
an
d n
u
mber of mo
d
u
les
equal to 10
0 per a
r
ray, each PV gene
ration produ
ce
d 165.28
3 kW ele
c
tri
c
al p
o
we
r gen
eration.
The WTG u
n
i
t
con
s
ide
r
ed
here i
s
a
unit
with 500
kW
output po
we
r rating. Th
e
power
cu
rve for
this
WTG us
ed Vis
t
as
V39
rating 500
kW [16].
T
he
i
ndu
ction gen
erato
r
circuit para
m
eters
for
th
e
same
unit
are given i
n
[1
5] with th
e fo
llowing
pa
ra
meters give
n
in p.u. valu
e
s
: R1=0.005
9
86,
X1=0.08
212,
R2
=0.01
690,
X2=0.10
722
5
,
Xm= 2.556
1
and X
c
=2.55
61. The
win
d
spe
ed in
put for
power flo
w
a
nalysi
s
i
s
vari
ed fro
m
1
1
to
15m /
s
. Th
e
ca
se
s p
r
e
s
en
ted WTG m
o
del a
s
PQ
no
de
and PV node
. The load flow an
alysis
wa
s perfo
rm
ed by using
per-unit valu
es on a ba
se
100
kVA and was
solved for 0.0
001 ph
ase voltage mism
atch.
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ISSN:
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930
Unb
a
lan
c
ed
Active
Distri
b
u
tion Analysi
s
with R
ene
wable Di
strib
u
ted Ener
gy Re
sou
r
c
e
s (S
yaf
ii)
25
(a)
2 unit PV Conne
cted
(b)
2 unit WTG
Conne
cted
Figure 3. IEEE 13 node te
st feede
r
3.2. The IEEE 8500-Nod
e
Test Fe
eder
The 8
500
-no
de te
st feed
er i
s
a
ra
di
al
dist
ributio
n
feed
er co
nsi
s
ting
of 1
177 CT
distrib
u
tion transfo
rme
r
. All the servi
c
e
s
from
the dist
ribution tran
sfor
me
r to the l
oad have
be
en
simplified to
be identical runs of 4/0 tri
p
lex, 50
ft in
lengh. Thu
s
, it is a moderately large ci
rcuit
that sho
u
ld b
e
suffici
ent to
exercise mo
st dist
ributio
n
system
anal
ysis al
go
rith
ms a
nd p
r
ov
e the
ability to handle larg
e scal
e probl
em
s.
T
he simplifie
d circuits
summ
erized in Fig
u
r
e 4.
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TELKOM
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Vol. 13, No. 1, March 2
015 : 21 – 31
26
Figure. 4 IEEE 8500 nod
e unbal
an
ce di
stributio
n fee
der
The la
rge
un
balan
ce
d loa
d
co
nne
cted
to
the 120/2
4
0
V ce
nter-ta
pped t
r
an
sformer via
50ft servi
c
e li
nes
solved
u
s
ing a
n
iterati
v
e forwa
r
d a
n
d backwa
r
d swee
p analy
s
i
s
metho
d
ba
sed
on voltage drop analysi
s
o
f
Figure 5. The volt
age drop analysi
s
u
s
ing Kirchh
off’s voltage an
d
curre
n
t
la
ws are re
peate
d
until
converg
ence
i
s
a
c
hie
v
ed. The
met
hod
extended
in the
seque
nce
comp
one
nt base
d
method
es.
Figure. 5. Center tap tran
sformer m
odel
The
se
cond
ary line lo
sses
cal
c
ulate
d
after Van
and Vb
n o
b
tained fo
r
both CT
transfo
rme
r
n
ode an
d load
node u
s
in
g:
S
losses_
aa
’
= I
aa
’
V
an
+ (-I
aa
’
)V
a’
n
(1)
S
losses_
bb
’
= I
bb
’
V
bn
+ (-I
bb
’
)V
b’
n
(2)
Whe
r
e:
S
losses
_aa
’
is power l
o
sse
s
alon
g line a to a’
, S
lo
sses_bb
’
is power losse
s
alo
ng line a to a’
Therefore the
total seco
nd
ary line losse
s
is:
S
losses
= S
losse
s_aa
’
+ S
l
o
s
s
e
s
_bb’
(3)
4. Results a
nd Analy
s
is
4.1. Unbalanced distri
bution s
y
stem IEEE 13 node
This se
ction studie
s
the system
perfo
rmance
by co
nne
cting DE
R of
co
gen
eration, PV,
wind turbi
ne,
and hybrid
generat
ion
unit
s
in the unbal
anced di
st
ri
bution net
works. The IEEE 13
node fee
der and the large scala IE
EE 8500 no
de ar
e used
for active d
i
stributio
n sy
stem
analysi
s
. Th
e
variation
of
wind
sp
eed
(m/s) fo
r
WT
G, sol
a
r
radi
ation (W/m²)
and tem
perature
(°C) for PV are carrie
d in the simulatio
n
.
The
simul
a
tio
n
was pe
rformed
by varyi
ng th
e
temp
e
r
ature a
nd
su
n irradi
an
ce.
Based
o
n
the PV model
have b
een
d
e
velope
d in [
9
], the maxim
u
m outp
u
t po
wer of PV ge
neratio
n
can
be
cal
c
ulate
d
. The re
sults at
variou
s mod
u
l
e temperatures are given i
n
Table 1.
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Unb
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Active
Distri
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u
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ene
wable Di
strib
u
ted Ener
gy Re
sou
r
c
e
s (S
yaf
ii)
27
Table 1. Maxi
mum po
wer o
u
tput at various tempe
r
atu
r
e
Value
Tem
p
erat
ure (
C)
25
50 75
Vmav (Volt)
21.417
19
16.641
Imax (Am
pere
)
7.717
7.692
7.637
Pmax (Watt
)
165.283
146.149
127.094
The PV mo
d
u
le temp
erat
ure i
s
va
ried i
n
unb
alan
ce
d
power flo
w
simulation. Th
e po
we
r
flow results f
r
om thi
s
sim
u
lation a
r
e
shown in
Fi
gu
re 6.
The
re
sults
sho
w
tha
t, the voltage
is
increa
sed by
PV units inst
alled in the n
e
twork.
Ho
we
ver the voltages in ph
ase A for all node
s of
the network pre
s
ent a
redu
ction in t
heir a
m
plitud
e be
cau
s
e
of the incre
a
se PV mo
dule
temperature
s
. This i
s
d
ue
to the in
cre
a
se of
PV temp
eratu
r
e d
e
cre
a
se
d in m
a
ximum PV po
wer
gene
ration a
s
sho
w
n in Ta
ble 1.
Figure. 6 Voltage ph
ase A results of PV model un
de
r different temp
eratu
r
e
The p
o
wer fl
ows have
be
en
chan
ged,
whe
n
PV tem
peratu
r
e
s
a
r
e
ch
ange
d. Th
e po
we
r
flow in
some
lines o
r
transf
o
rme
r
s h
a
ve
been
in
cre
a
sed a
n
d
othe
rs d
e
cre
a
sed
by incre
a
sed
PV
temperature.
The directio
n and amo
unt o
f
power flo
w
are de
pen
ds
on PV size a
nd location.
The re
active
power flow f
o
r line 67
1 to 680 eq
ual
to zero, beca
u
se the
r
e i
s
no load
con
n
e
c
ted to
this n
ode.
Th
e line
s
whi
c
h
its
pha
se
co
nne
cted to
d
u
mmy no
de
also
have
a
zero
power flo
w
d
ue to both e
n
d
node volta
g
e
are th
e sa
me. For exa
m
ple, the line
from nod
e ID 632
to nod
e ID
6
45 i
s
two
-
p
h
a
s
e li
ne
witho
u
t pha
se
‘a’,
so th
e line
flo
w
s in p
h
a
s
e ‘
a
’ eq
ual to
ze
ro.
Actually, this line is dum
my line doe
s not
exist in the real network.
The re
sult
s at various mo
d
u
le irradian
ce
leve
ls are gi
ven in Table
2. The sun i
r
radian
ce
is vari
ed in
u
nbala
n
ced p
o
w
er flow
sim
u
lation. Th
e power
flo
w
re
sults
f
r
om
thi
s
simulatio
n
are
sho
w
n i
n
Fig
u
re
7. It ca
n
be ob
se
rved
that the vo
lta
ges in p
h
a
s
e
A for all
nod
e
s
of the
net
work
pre
s
ent
are i
n
crea
sed
in t
heir
amplitud
e be
ca
use
of
the in
cre
a
se i
rra
dian
ce l
e
vel. This is du
e to
the in
cre
a
se
of PV irradia
c
e mad
e
the
in
cre
a
sed
of m
a
ximum PV p
o
we
r g
ene
rati
on a
s
sh
own
in
Table 2.
0.9
0.92
0.94
0.96
0.98
1
1.02
650
632
633
634
645
646
671
672
680
684
611
652
692
675
Vo
l
t
a
g
e
Phase_A
,
pu
under
dif
f
er
en
t
Te
m
p
e
r
a
t
u
r
e
T
=
25
T
=
50
T
=
75
Without
DER
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TELKOM
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Vol. 13, No. 1, March 2
015 : 21 – 31
28
Table 2. Maximum po
wer
output at various irra
dian
ce level
Value
Irradiance Le
v
e
l
(W/m
2
)
600 800
1000
Vmax (Volt)
20.816
21.155
21.417
Imax (Am
pere
)
4.606
6.16
7.717
Pmax (Watt
)
95.887
130.317
165.283
The active po
wer flo
w
s h
a
ve been chan
g
ed,
whe
n
irra
dian
ce level chang
ed. The
power
flow in
some
lines o
r
transf
o
rme
r
s h
a
ve
been
in
cre
a
sed a
n
d
othe
rs d
e
cre
a
sed
by incre
a
sed
PV
irra
dian
ce lev
e
l. The dire
ction and am
ount of powe
r
flow are al
so de
pend
s
on PV size
and
loc
a
tion.
Figure. 7 Power flo
w
re
sul
t
s of
PV model unde
r different irra
dian
ce
The second
system i
s
a
modified IEEE 13
node feeder with t
w
o
unit
s
of WTG DG
con
n
e
c
ted at node ID 63
4 and nod
e ID 672. The WT
G unit con
s
id
ered h
e
re i
s
a unit with 500kW
output p
o
we
r rating. T
he
wind
sp
eed
i
nput for po
wer flo
w
a
nalysis is va
rie
d
from
11 to
15
m /s.
The po
we
r fl
ow results a
r
e given in Fi
gure
8 which
sho
w
s the n
ode voltag
e
magnitud
e
h
a
ve
been
in
cre
a
sed by
an i
n
crease in
win
d
spe
ed. Thi
s
i
s
b
e
cau
s
e th
e in
cre
a
se in
wind
speed
made
the incre
a
se i
n
win
d
p
o
wer gene
ratio
n
a
s
sho
w
n i
n
T
able 3.
The
Rea
c
tive po
wer
con
s
um
ed
by
wind turbun
e
varies for ev
ery test ca
se,
and
its value also d
epe
n
d
s on n
ode v
o
ltage at WT
G
con
n
e
c
tion, which vari
ed d
u
ring p
o
wer fl
ow iteratio
n p
r
ocess.
Table 3. Maxi
mum po
wer o
u
tput at various wi
nd spee
d
Node
Voltag
e Phase
_
A
,
pu
s = 11
s = 12
s = 13
s = 14
s = 15
P (kW)
381 440 478 494 499
0.86
0.88
0.9
0.92
0.94
0.96
0.98
1
1.02
650
632
633
634
645
646
671
672
680
684
611
652
692
675
Vo
l
t
a
g
e
Phase_A
,
pu
under
dif
f
er
en
t
Irr
a
dian
G
=
600
G
=
1000
Without
DER
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TELKOM
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ISSN:
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930
Unb
a
lan
c
ed
Active
Distri
b
u
tion Analysi
s
with R
ene
wable Di
strib
u
ted Ener
gy Re
sou
r
c
e
s (S
yaf
ii)
29
The
power flow
re
sults from thi
s
simul
a
ti
on a
r
e
sho
w
n i
n
Fi
gure
8. Th
e
re
sul
t
s sho
w
that, the volta
ge is in
crea
sed by WTG u
n
its inst
all
ed i
n
the netwo
rk. The voltage
s in pha
se A for
all node
s are
incre
a
sed in
their amplitu
de be
ca
u
s
e
of the wind speed in
crea
sed. The activ
e
power
flo
w
s also have be
en chan
ged, whe
n
wi
nd speed
i
s
ch
an
ged.
Th
e
di
re
ction and am
ount
of powe
r
flow are also dep
end
s on WT
G size and lo
cation
Figure. 8 Power flo
w
re
sul
t
s of WTG m
odel un
der dif
f
erent win
d
speed
The va
riation
of win
d
spe
e
d
(m/
s
) for WTG, solar radi
ation
(W/m
²
)
and te
mpe
r
at
ure
(°
C)
for photovolt
a
ic impa
ct
s h
a
ve been
si
mulated. Th
e
simulation
result
s sh
ow t
hat the pro
p
o
se
d
DG mo
del ca
n be used to analysi
s
DG impact
s
in un
balan
ce
d dist
ribution
syste
m
.
4.2. Test on
Large Scale
Unba
la
nced Distribu
tion Sy
stem
The IEEE 8500-node test
feeder i
s
a
latest
data provided
by IEEE PES di
stribution
system a
naly
s
is
sub
c
o
mmi
ttee used to t
e
st the
alg
o
ri
thm for larg
e
system p
r
obl
em. The 85
0
0
-
node te
st fee
der i
s
a
radial
distrib
u
tion f
eede
r c
ontain
s
11
77
CT di
stributio
n tra
n
s
form
er
con
n
e
ct
to 1177 loa
d
s, one set of regulato
r
s at t
he su
bs
tatio
n
and thre
e se
ts of voltage regulato
r
s al
o
n
g
the line and f
our capa
cito
rs.
The load flow analysi
s
for t
he IEEE 8500 nod
e was
perform
ed usi
ng per-unit values on
a basi
s
100
KVA and solved this sy
stem in 9 iterations for 0.001 phase voltage mismat
ch. The
different on voltage mag
n
itude
s re
sult a
r
e 0.024
p.u
and re
sid
ue
curre
n
ts are 0.88 Ampere
in
averag
e. Th
e
Table
4T
abl
e
sho
w
s the
sel
e
cte
d
co
mpari
s
o
n
of
seq
uen
ce
co
mpone
nt met
hod
and forward/
backward based Open
DS
S program [
17] for IEEE
8500-node test sy
stem. The
result are alm
o
st sam
e
, the difference ca
use of
ce
nter-tappe
d tran
sformer
m
odeli
ng that exist in
for IEEE 8500-node test system.
The effect of DERs pen
etration on volta
ge
profile a
n
d
system lo
sse
s
for sy
ste
m
8500-
node i
s
given
in Ta
ble 5. T
he result sho
w
s that, the
minimum m
a
gnitude volta
ge have
in
cre
a
se
d
by increa
se
n
u
mbe
r
an
d si
ze of
DER u
n
its in
sta
lled
in the net
wo
rk. The
be
st result fo
r volta
ge
improvem
ent
and lo
ss
red
u
ction fo
r this sy
stem
al
so for maximu
m DG
s in
stalled ca
se
5. The
variation of
DERs lo
catio
n
is a
s
sho
w
n in
case 3a,
3b, 4a
and
4b of Ta
ble
4 gave im
pa
ct in
voltage profil
e improvem
e
n
t and network loss redu
ction.
0.86
0.88
0.9
0.92
0.94
0.96
0.98
1
1.02
650
632
633
634
645
646
671
672
680
684
611
652
692
675
Vo
l
t
a
g
e
Phase_A
,
pu
under
dif
f
er
en
t
wind
speed
s
=
11
s
=
15
Without
DER
Evaluation Warning : The document was created with Spire.PDF for Python.
ISSN: 16
93-6
930
TELKOM
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Vol. 13, No. 1, March 2
015 : 21 – 31
30
Table 4 Results of IEEE 85
00-node
test case under
2.
66 GHz PC
Cases
O
p
e
n
DSS Pro
g
ra
m
S
e
q
ue
nce co
m
p
onen
t
Pro
g
ram
Min p.u Voltage
0.911
0.909
Max p.u Voltag
e
1.050
1.050
Total Po
w
e
r
Gen
e
ration (MW)
12.045
12.026
Total Reactive Power (MV
a
r)
1.445
1.320
Losses (MW)
1.273
1.251
Mismatch (p.u voltage)
0.001
0.001
Table 5. Re
sult of 8500 Bus ADS test case
Cases
DERs L
o
cati
ons
Min |V|
p.u
DER Sup
p
l
y
Losses
KW KVar
(KW)
1 -
0.9137
0
0
1239.29
2 2623
(Co
gen)
0.9255
60
143.19
1202.60
3a 2623(C
)
,
3571
(P
V)
0.9272
100.03
131.03
1292.97
3b 2623(C
)
,
2937
(P
V)
0.9282
100.03
124.09
1244.78
4a 2623(C
)
,
3571
(W
TG)
0.9294
104
110.70
1176.26
4b 2623(C
)
,
2937
(W
TG)
0.9300
104
110.70
1190.82
5
2
6
2
3(C
)
,
2
93
7
(
PV
)
35
71
(
WT
G)
0
.
9
2
96
144.
03
1
0
7.
55
11
6
7.4
8
The va
riation
DG l
o
cation i
s
studie
d
in
this
simul
a
tion
for
ca
se
s
3a,
3b, 4
a
a
nd
4
b
. In the
ca
se 3b which PV generat
ion unit con
n
e
cted to bu
s ID 2937 have
a better result compa
r
ed
to
ca
se 3
a
in
which
a PV ge
neratio
n unit i
s
conn
ecte
d to bu
s ID 3
5
7
1
. The mini
m
u
m voltage h
a
ve
been in
crea
sed from 0.9
2
72 p.u for
ca
se 3a to
0.92
82 for
ca
se 3
b
as
well a
s
l
o
sse
s
de
crea
sed
from 1
292.97
kW for case
3a to 1
244.7
8
kW fo
r
ca
se 3b.
Ho
wev
e
r, for the
ca
se
4a a
nd
4b
the
increa
sed
of minimum volt
age did
not
make th
e lo
sse
s
de
crea
se
. The ca
se
4
b
whi
c
h
WT
G
con
n
e
c
ted to
bus ID 2
937
have a bette
r voltage
profile but wo
rse
system lo
sses comp
are
d
to
ca
se 4a
whi
c
h WTG
con
n
e
cted to bu
s ID 357
1.
5. Conclusio
n
The pap
er h
a
s presented
rene
wabl
e distribut
e
d
en
ergy re
sou
r
ses analy
s
is
as thre
e-
pha
se
re
sou
r
ce in
un
bala
n
c
ed
dist
ributi
on loa
d
flo
w
comp
utation.
The
rene
wa
b
l
e DE
R mo
de
ls
that have
be
en
con
s
id
ere
d
comp
rise o
f
photovol
tai
c
(PV)
and
wi
nd tu
rbine
ge
neratio
n
(WT
G
).
The voltage
-controlled
no
de an
d comp
lex power inj
e
ction
nod
e
are
used in t
he mo
dels. T
h
e
cente
r-ta
ppe
d (CT
)
tra
n
sf
orme
r loa
d
m
odel ha
s b
e
e
n
inclu
ded in
prog
ram. Th
e
variation of
wind
spe
ed (m/s) for WT
G, sola
r radiatio
n (W/m²)
and tem
peratu
r
e (°C) for PV have
been si
mulat
ed.
The
simul
a
tio
n
re
sult
s
sho
w
that th
e p
r
o
posed m
e
tho
d
s
ca
n b
e
u
s
ed to
analy
s
e
DER imp
a
ct
s in
the unb
alan
ced me
she
d
a
nd ra
dial di
st
ribution
sy
ste
m
. The integ
r
ation of re
ne
wabl
e DE
R i
n
to
an exi
s
ting
di
stributio
n n
e
twork can im
p
r
ove th
e vo
lta
ge p
r
ofile,
an
d redu
ce
total
syste
m
lo
sse
s
.
The
simulati
on re
sult
s show th
at DE
Rs
si
ze a
n
d
locatio
n
are
importa
nt factors to imp
r
ove
voltage profil
e and line lo
ss red
u
ctio
n.
Ackn
o
w
l
e
dg
ment
The a
u
tho
r
s gratefully
a
c
kno
w
led
ge
the a
ssi
stan
ce
ren
dered
by the F
a
culty of
Enginee
ring,
Andala
s
Univ
ersity for pa
rtially
funding this research in DIPA F
T
Unan
d 20
14
(Contract No.
015/PL/
SPK/PNP/FT-Unand/2014).
Referen
ces
[1]
H Nehrir, Wan
g
C, Sha
w
S
R
. Fuel cells:
promisin
g dev
ice
s
for di
stribute
d
gen
eratio
n.
IEEE Power
and En
ergy Ma
ga
z
i
n
e
. 20
06; 4(1): 47-5
3
.
[2]
Kroposk
i
B, L
a
sseter R, Ise T
,
Morozumi
S, Papat
h
a
n
a
ssio
u
S, Hatzi
a
rg
yr
iou
N. A l
ook
a
t
microgri
d
techno
lo
gies a
nd testing
proj
ects from arou
nd the
w
o
r
l
d.
IEEE Pow
e
r and Energy Ma
ga
z
i
n
e
. 20
08.
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