Internati
o
nal
Journal of P
o
wer Elect
roni
cs an
d
Drive
S
y
ste
m
(I
JPE
D
S)
Vol
.
5
,
No
. 2, Oct
o
ber
2
0
1
4
,
pp
. 19
5~
20
2
I
S
SN
: 208
8-8
6
9
4
1
95
Jo
urn
a
l
h
o
me
pa
ge
: h
ttp
://iaesjo
u
r
na
l.com/
o
n
lin
e/ind
e
x.ph
p
/
IJPEDS
Operation and Control of Gr
id Connect
ed Hyb
r
id AC/DC
Microgrid using Various RES
K
o
da
nd
a Ram R
B P
U
S
B,
M.
V
e
n
u
Go
pa
la
Ra
o
Department o
f
Electrical and
Electronics Engin
e
ering, K
L Univ
er
sity
, Guntur
, AP, INDIA
Article Info
A
B
STRAC
T
Article histo
r
y:
Received Apr 30, 2013
Rev
i
sed
Jan
1
0
, 2
014
Accepted
Feb 24, 2014
This paper pro
poses a Hy
br
id
AC/DC
M
i
crogrid in all
i
an
ce
with P
hoto
Voltai
c
(P
V) energ
y
, W
i
nd Ener
g
y
a
nd Proton Exchange Membrane (PEM)
F
u
el ce
lls
. M
i
cr
ogrids
are be
co
m
i
ng increas
ing
l
y a
ttr
act
ive to
th
e res
ear
chers
because of
the
l
e
ss greenhouse
gases, low runn
ing cost,
and fl
exibil
it
y
to
operat
e
in
con
n
ect
ion with ut
ilit
y gr
id.
The
H
y
brid AC/D
C Microgrid
constitut
e
s independent AC and
DC subgrids,
where all th
e corresponding
s
ources
and loa
d
s
are conn
ect
ed t
o
their r
e
s
p
ec
tiv
e bus
es
and th
es
e bus
es
are
interf
aced using
an interfa
cing
convert
er. Th
e H
y
brid AC/DC Microgrid
increases s
y
st
em
effici
ency
b
y
reduc
i
ng th
e
m
u
ltiple r
e
verse conversions
involved in con
v
ention
a
l RES integration to grid. A Small Hy
b
r
id AC/DC
Microgrid
in grid connected
mode
was modeled
and simulated in
MATLAB-
SIMULINK environment. The simulati
on results
prove the stable operation
considering
the
uncertainty
of g
e
nerations and
lo
ads.
Keyword:
Fu
el Cells
Hy
bri
d
P
o
wer
Sy
stem
s
Interfacing C
o
nve
rter
M
i
cro gri
d
s
Solar Ene
r
gy
Wi
n
d
E
n
e
r
g
y
Copyright ©
201
4 Institut
e
o
f
Ad
vanced
Engin
eer
ing and S
c
i
e
nce.
All rights re
se
rve
d
.
Co
rresp
ond
i
ng
Autho
r
:
Kod
a
n
d
a
Ram
R B P
U S B,
Depa
rt
m
e
nt
of
El
ect
ri
cal
and
El
ect
roni
cs
E
n
gi
nee
r
i
n
g,
K L Un
iv
ersity, Vadd
eswaram
G
u
n
t
ur
D
i
str
i
ct, And
h
r
a
Pr
ad
esh
,
IN
DI
A – 52
145
6
Em
a
il: b
a
laj
i
r19
86@k
l
u
n
i
v
e
rsity.in
1.
INTRODUCTION
A Microg
ri
d
is a sm
a
ll g
r
id
form
ed
b
y
b
a
n
k
i
n
g
m
u
ltip
le en
erg
y
reso
urces an
d
l
o
ads
to
enh
a
n
c
e
o
v
e
rall reliab
ility an
d
in
d
e
p
e
n
d
e
n
t
adv
a
n
t
ag
es. Now-a-d
a
ys, it
is
m
o
re p
r
eferred
to
in
teg
r
ate ren
e
wab
l
e
ener
gy
res
o
u
r
c
e
s t
o
M
i
crog
ri
d t
o
l
e
ssen t
h
e
C
O
2
em
i
ssi
on and f
o
ssi
l
f
u
el
con
s
um
pt
i
on.
The ba
n
k
ed M
i
cro
g
ri
d
can be
operate
d
either in c
onnection
t
o
m
a
in g
r
i
d
or
ope
r
a
t
e
d l
i
k
e i
s
ol
at
ed “i
sl
an
ded”
[1]
.
No
w-a
-
da
y
s
, DC
loads like LE
D’s
,
Electric Vehicles
an
d
ot
he
r El
ect
ro
ni
c Gad
g
ets are being increasi
ngly use
d
due
to their
inhe
rent a
d
vantages. T
h
ree Phase
AC
P
o
we
r system
s have
existed for ove
r
100 years
due to their efficient
tran
sform
a
t
i
o
n
at d
i
fferen
t
vo
ltag
e
lev
e
ls an
d tran
sm
issi
on over l
o
ng
distances. T
h
e inhere
nt cha
r
acteristics
of
ro
tating
m
ach
in
es m
a
k
e
it feasib
le fo
r larg
er
p
e
ri
o
d
.
To c
o
nnect
t
h
e co
nve
nt
i
o
nal
AC
sy
st
em
to t
h
e
re
ne
wab
l
e reso
u
r
ces,
AC
M
i
cr
og
ri
d
s
ha
ve
bee
n
pr
o
pose
d
a
n
d
DC
p
o
w
er
fr
o
m
t
h
e vari
ou
s
reso
u
r
ces l
i
k
e
PV
pa
nel, Fuel
cells etc., are
conve
r
ted i
n
to
AC in
or
der t
o
c
o
nne
ct
t
o
an AC
gri
d
, w
h
i
c
h a
r
e i
m
pl
ant
e
d by
AC
/
D
C
C
o
n
v
ert
e
rs an
d DC
/
D
C
C
onve
rt
ers
[
2
]
.
In a
n
AC Grid, several conv
erters are
requ
ired
for
v
a
ri
ou
s home an
d
o
f
fice facilities to
prov
id
e req
u
i
red
DC
vol
t
a
ge
s.
AC
/
D
C
/
AC
co
n
v
er
t
e
rs are c
o
m
m
onl
y
used a
s
d
r
i
v
es i
n
order t
o
control the
s
p
eed of AC m
o
tors in
in
du
stries.
Recently DC
gri
d
s are
res
u
rging
due
to
de
velopm
ent and de
ploym
e
nt of re
ne
wable
DC resources
an
d th
eir inh
e
ren
t
ad
v
a
n
t
ag
e
for
DC lo
ad
s in
resid
e
n
tial,
co
mmercial and
indu
strial app
licatio
n
s
. Th
e DC
M
i
crog
ri
d
has been
pr
o
pose
d
[3]
.
H
o
weve
r,
fo
r co
nve
nt
i
o
n
a
l
AC
l
o
ads D
C
/
A
C
i
nvert
e
r
s
are req
u
i
r
e
d
and
AC
sources
are c
o
nnecte
d
using
AC/DC C
o
nve
r
ters.
Mu
ltip
le rev
e
rse con
v
e
rsion
s
requ
ired
in
i
n
d
i
v
i
du
al AC
or DC
g
r
i
d
m
a
y
ad
d
add
itio
n
a
l
lo
ss to
t
h
e
syste
m
o
p
e
rati
o
n
and
will mak
e
th
e cu
rrent h
o
m
e and
o
f
fice app
lian
ces m
o
re co
m
p
lic
ated
in d
e
si
g
n
and
Evaluation Warning : The document was created with Spire.PDF for Python.
I
S
SN
:
2
088
-86
94
I
J
PED
S
Vo
l.
5
,
No
.
2
,
O
c
t
o
b
e
r 201
4 :
1
95 –
20
2
19
6
ope
ration [4].
The c
u
rrent
re
search i
n
the e
l
ectric powe
r i
n
du
stry is sm
art g
r
i
d
.
On
e of th
e m
o
st i
m
p
o
rtan
t
fu
t
u
res
o
f
a smart g
r
i
d
is th
e ad
v
a
n
c
ed
stru
ct
u
r
e
wh
ic
h
can
facilitate th
e co
nn
ection
s
o
f
d
i
fferen
t
AC
an
d
DC
gene
rat
i
o
n sy
st
em
s, energy
st
ora
g
e o
p
t
i
o
ns
and
vari
ous
AC an
d
DC lo
ad
s with
th
e
o
p
ti
m
a
l asset u
til
izatio
n
and
ope
rationa
l efficiency. The powe
r
electronics conve
rt
er pl
ays a
m
o
st i
m
p
o
r
tan
t
ro
l
e
to
in
terfacing
AC
an
d DC
grid
s,
wh
ich
m
a
k
e
s fu
ture
g
r
id m
u
ch
sm
arter.
A Hyb
r
i
d
AC/DC
Microgrid
is
p
r
op
o
s
ed
t
o
redu
ce
p
r
o
cesses of m
u
ltip
le rev
e
rse con
v
e
rsio
n
s
in
an
in
d
i
v
i
d
u
a
l
AC o
r
DC
g
r
i
d
an
d
t
o
facilitate
th
e co
nn
ecti
o
n
of v
a
riou
s en
erg
y
sou
r
ces, sto
r
ag
e d
e
v
i
ces and
l
o
ads
[
5
]
.
The
adv
a
nce
d
po
wer el
ect
r
o
ni
c devi
ces
an
d
cont
rol
t
ech
ni
que
s are
use
d
t
o
ha
r
n
ess m
a
xi
m
u
m
po
we
r f
r
om
re
newa
bl
e
po
we
r
so
urces
, t
o
m
i
ni
m
i
ze po
wer
t
r
ans
f
er
bet
w
ee
n
AC
an
d
DC
net
w
or
ks.
P
V
s
y
st
em
,
PEMFC con
s
ti
tu
tes th
e
DC En
erg
y
so
urces;
W
i
nd
system
c
o
n
s
titu
tes t
h
e
AC en
erg
y
so
urce,
wh
ereas Battery
and Conventional Grid are
us
ed as
s
t
or
a
g
e de
v
i
c
e
s
w
h
en
eve
r
r
e
qu
ir
ed
.
2.
SYSTE
M
CO
NFIG
U
RATI
O
N A
N
D
M
O
DELING
Fig
u
re
1
illu
st
rates th
e co
m
p
act represen
tatio
n
of
p
r
o
p
o
s
ed
Hybrid
Micro
g
rid Con
f
i
g
uratio
n
.
The
Hy
bri
d
M
i
cr
o
g
ri
d
was
fo
rm
ed
by
a
DC
s
u
b
g
r
i
d
an
d a
n
AC
s
u
b
gri
d
. Eac
h
s
u
b
gri
d
has i
t
s
o
w
n
sou
r
ce
s
ele
m
ents, stora
g
e elem
ents and loa
d
s
of the
sam
e
ca
te
gory
gr
ou
pe
d t
o
get
h
er s
o
as t
o
re
duce t
h
e am
ou
nt
o
f
powe
r convers
i
on
require
d
. B
o
th s
u
b
grids a
r
e interfaced
using i
n
terfaci
ng
converters. Interfaci
ng
converters
are th
e b
i
d
i
rectio
n
a
l co
nv
erters, and
th
eir maj
o
r ro
le is
t
o
pr
o
v
i
d
e bi
di
re
ct
i
onal
ener
gy
t
r
ans
f
er bet
w
e
e
n t
h
e
su
b grid
s,
d
e
p
e
n
d
i
n
g
on
t
h
e
p
r
ev
ailin
g
i
n
ternal sup
p
l
y
–
d
e
man
d
co
nd
ition
s
.
Th
e fo
rm
ed
Hyb
r
id
g
r
i
d
can
b
e
tied
to
Utility g
r
id
u
s
i
n
g
an
In
tellig
en
t Tran
sfer
Switch at p
o
i
n
t
of
com
m
on coupl
i
ng as i
n
co
nve
nt
i
onal
AC
g
r
i
d
s. I
n
g
r
i
d
t
i
e
d
m
ode of o
p
er
a
t
i
on, su
r
p
l
u
s e
n
er
gy
i
n
t
h
e i
n
t
e
rnal
su
b grid
s if
an
y can
b
e
inj
e
cted
to
th
e
u
tility g
r
id
w
ithou
t v
i
o
l
ating
the lo
cal u
tility
ru
les.
Similarl
y, th
e
sh
ortfall in bo
t
h
th
e su
b grid
s
if an
y
can
b
e
ab
sorb
ed fro
m
th
e
u
tility g
r
id
.
Fi
gu
re
1.
A
C
o
m
p
act
represe
n
t
a
t
i
on o
f
t
h
e
pr
op
ose
d
Hy
b
r
i
d
M
i
cro
g
ri
d
2.
1. Propose
d
Hybrid
Micr
ogrid Confi
g
ur
ati
o
n
PV
Ar
ray
(
40
k
W) a
n
d PEM
F
u
el
C
e
l
l
(5
0
k
W) a
r
e c
o
n
n
ect
ed t
o
DC
bu
s t
h
r
o
ug
h i
n
de
pe
nde
nt
DC
/
D
C
b
o
o
s
t con
v
e
rter to sim
u
late
DC so
urces.
Cap
acito
rs
C
pv
and
C
fc
are
u
s
ed t
o
s
u
pp
res
s
t
h
e
hi
g
h
f
r
e
que
ncy
r
i
pp
les of
t
h
e PV
an
d FC
ou
tpu
t
vo
ltag
e
.
Also
, a
wind
t
u
rb
in
e
g
e
n
e
rat
o
r
(W
TG) wit
h
DFIG (5
0kW) an
d
u
tility
g
r
i
d
are co
nn
ected
to
AC
b
u
s
to
sim
u
late AC Sou
r
ces.
In
ad
d
ition
,
a
b
a
ttery (6
5Ah
)
and
sup
e
r cap
acit
o
r (0
.5
F) are i
n
d
i
v
i
du
ally con
n
ected
as en
erg
y
stor
ag
es to
D
C
bu
s th
ro
ugh
bu
ck
-b
oo
st (D
C/
DC
) converter. The DC loa
d
was
considere
d
as
pure
resistive loa
d
and
AC loads
are c
onsi
d
ere
d
wit
h
RL
C
wh
ich
are d
y
na
m
i
c in
n
a
tu
re. Bo
th
t
h
e lo
ad
s are
v
a
r
i
ab
le b
e
tw
een
20kW
–
40kW
. Rated
vo
l
t
ag
es fo
r
b
o
t
h
b
u
s
es ar
e co
nsid
er
ed
as 400V
. Th
e p
a
r
a
m
e
ter
s
o
f
th
e Hy
b
r
i
d
Microg
ri
d
are tabu
lated
in Tab
l
e 3
.
2.
2.
Modeling
of P
V
P
a
nel
Fi
gu
re
2 s
h
ows
t
h
e e
qui
val
e
nt
ci
rcui
t
of a
P
V
Panel
m
odel
e
d
by
a c
ont
r
o
l
l
e
d c
u
r
r
ent
s
o
ur
ce.
I
pv
and
V
pv
are the term
inal current a
n
d
v
o
l
t
a
ge
of t
h
e P
V
pa
nel
,
res
p
e
c
t
i
v
el
y
.
The c
u
rre
nt
o
u
t
p
ut
o
f
t
h
e pa
nel
i
s
m
odel
e
d
usi
n
g t
h
r
ee Eq
uat
i
on
(1
), (
2
),
(3
) [
6
]
-
[
7
]
.
Th
e param
e
t
e
rs t
h
at
were t
a
ke
n i
n
t
o
c
onsi
d
erat
i
on
fo
r si
m
u
l
a
t
i
on a
r
e
sho
w
n i
n
Ta
bl
e 1.
Evaluation Warning : The document was created with Spire.PDF for Python.
I
J
PED
S
I
S
SN
:
208
8-8
6
9
4
O
p
era
tion
an
d Co
n
t
ro
l
o
f
G
r
i
d
C
o
nn
ected
Hyb
r
id
AC/D
C Micro
g
rid
u
s
ing
…
(Ko
dand
a Ram
R B
P U
S
B)
19
7
1
(
1
)
.
(
2
)
.
(
3
)
Fi
gu
re
2.
Eq
ui
val
e
nt
ci
rc
ui
t
o
f
a
PV
Pan
e
l
Tabl
e 1. Param
e
t
e
rs
o
f
Ph
ot
o
v
o
l
t
a
i
c
Panel
Sy
m
b
ol
Description
Value
V
oc
Rated open cir
c
uit
voltage
403 V
I
p
h
Photocur
r
e
nt
I
sa
t
M
odule r
e
ver
s
e satur
a
tion cur
r
e
nt
Q
Electron charge
1.
602 x 10
-1
9
C
A
Ideality factor
1.
50
K
Boltzm
a
nn Constant
1.
38 x 10
-
23
J/K
R
s
Series
resistance o
f
a PV cell
R
p
Parallel
resistance
of
a PV cell
I
sso
Short-circuit curre
n
t
3.
27 A
k
i
SC Current te
m
p
er
ature Coef
f
i
cient
1.
7 e
-3
T
r
Ref
e
rence Te
m
p
er
ature
301.
18 K
I
r
r
Reverse Saturation
current at
T
r
2.
0793e
-6
A
E
g
a
p
Energy of the band gap for silicon
1.
1 eV
n
p
Nu
m
b
e
r
of cells in
parallel
40
n
s
Nu
m
b
e
r
of
cells in
series
900
S
Solar Irradiation L
e
vel
0 ~ 1000 W
/
m
T
Surf
ace te
m
p
e
r
atur
e of
the PV
2.
3.
Modeling
of Fuel Cell
Fi
gu
re
3 sh
o
w
s t
h
e eq
ui
val
e
nt
ci
rcui
t
o
f
P
E
M
Fuel
cel
l
.
The
ohm
i
c
, act
i
v
at
i
on an
d c
once
n
t
r
at
i
o
n
resistances are represente
d with R
oh
m
i
c
,
R
act
, R
conc
respectively. C is the
m
e
m
b
rane capacitanc
e. The
M
e
m
b
rane
v
o
l
t
a
ge e
quat
i
on
i
s
gi
ve
n
by
E
q
ua
t
i
on
(4
).
1
(
4
)
The
output vol
t
age of t
h
e
P
E
M
F
C
i
s
gi
ven
by
(
5
):
(
5
)
-
Vc
+
E
R
co
n
c
R
ac
t
C
R
oh
m
i
c
V
fc
I
fc
Fi
gu
re
3.
Eq
ui
val
e
nt
ci
rc
ui
t
o
f
PEM
Fu
el
cel
l
Evaluation Warning : The document was created with Spire.PDF for Python.
I
S
SN
:
2
088
-86
94
I
J
PED
S
Vo
l.
5
,
No
.
2
,
O
c
t
o
b
e
r 201
4 :
1
95 –
20
2
19
8
2.
4.
Modeling
of
B
a
ttery
Battery is no
t
v
e
ry im
p
o
r
tan
t
in
grid
-tied
m
o
d
e
.
B
u
t
,
p
r
ovi
des a
n
ene
r
gy
st
o
r
a
g
e i
n
DC
s
u
b
g
r
i
d
,
whic
h can re
ducet
he m
u
ltiple reve
rse conve
r
sion, wh
eneve
r
re
qui
re
d. I
n
em
ergency
i
.
e., Gri
d
Fai
l
e
d
Co
nd
itio
n, th
ey p
l
ays a v
ital
ro
le in
po
wer b
a
lan
ce and
vo
ltag
e
stab
ility
. Th
e b
a
ttery was m
o
d
e
led
u
s
ing
a
cont
rol
l
e
d
n
onl
i
n
ear s
o
u
r
ce i
n
seri
es wi
t
h
a c
onst
a
nt
re
sista
n
ce. T
h
e State
Of C
h
arge
(S
OC)
of t
h
e bat
t
ery
is
gi
ve
n by
E
quat
i
on (
6
).
%
100
1
(6)
Whe
r
e
is the
e
x
tracted capaci
ty and
Q is
the
Maxim
u
m
capacity if battery.
2.
5.
Modeling
of
Wind Turbin
e
Gener
a
tor wi
th
DFIG
I
n
t
h
is
p
a
p
e
r
,
D
F
IG
w
a
s consid
er
ed
as a wo
und
ro
tor
i
n
du
ctio
n m
ach
in
e. The pow
er ou
tpu
t
P
m
from
a
W
T
i
s
det
e
r
m
i
n
ed by
[
3
]
.
A
50
k
W
DFI
G
pa
ram
e
t
e
rs, us
ed i
n
t
h
i
s
pa
per
are s
h
ow
n i
n
Tabl
e
2.
0
.5
,
(
7
)
Tabl
e 2.
Param
e
ters o
f
DF
IG
Sy
m
b
ol
Description
Value
P
no
m
No
m
i
nal power
50 kW
V
no
m
No
m
i
nal Voltage
400 V
R
s
Stator resistance
0.
0070
6 pu
L
s
Stator
inductance
0.
171 pu
R
r
Ro
to
r resistan
ce
0.
005 pu
L
r
Rotor
inductance
0.
156 pu
L
m
M
u
tual inductance
2.
9 pu
J
Rotor inertia constant
3.
1 s
n
p
Nu
m
b
er
of poles
6
V
dc
_
no
m
No
m
i
nal DC voltage of AC/DC/AC
conver
t
er
800 V
P
m
No
m
i
nal M
e
chanical power
45
W
3.
CONTROLLERS
The
Hy
b
r
i
d
M
i
cro
g
ri
d
co
nt
ai
ns si
x t
y
pes
of
co
nve
rt
ers
.
Al
l
t
h
e co
n
v
ert
e
r
s
ha
ve t
o
be
c
o
o
r
di
nat
e
l
y
co
n
t
ro
lled
with th
e u
tility g
r
id
to
su
pp
ly reliab
l
e, h
i
g
h
effici
en
cy, h
i
g
h
q
u
a
lity p
o
w
er for v
a
riab
le DC and
AC
loads
.
The controllers are pr
e
s
ent
e
d i
n
t
h
i
s
sect
i
on are co
or
di
nat
e
d su
ccessfu
lly in
bo
th
g
r
i
d
-tied. A
Direct
To
rqu
e
Con
t
rol Strateg
y
(DTC) with
feed
fo
rward
vo
ltag
e
com
p
ensation is selected
f
o
r D
F
IG
con
t
ro
l syste
m
[9]
.
3.
1.
B
oos
t Co
nve
r
t
er
In grid
tied m
o
d
e
, t
h
e co
n
t
ro
l
o
b
j
ectiv
e of the bo
ost conv
erter is to
t
r
ack th
e MPPT
o
f
the PV p
a
n
e
l
and
F
u
el
C
e
l
l
.
The
PV
Pa
nel
and
F
u
el
C
e
l
l
bo
ost
c
o
nve
rt
ers a
r
e
desi
g
n
ed
t
o
s
u
pp
ort
t
h
e
DC
b
u
s
vol
t
a
ge as
sho
w
n i
n
Fi
gu
r
e
4.
T
o
ac
hi
eve
m
a
xim
u
m
power
, P
&
O M
e
t
h
o
d
pr
o
pose
d
i
n
[
6
]
.
Fi
gu
re
4.
C
o
nt
r
o
l
Sc
hem
e
of P
V
C
e
l
l
an
d
PE
M
Fuel
cel
l
3.
2.
C
o
n
t
ro
l o
f
Bat
t
e
ry
B
a
t
t
e
ry
has hi
gh
ene
r
gy
de
n
s
i
t
y
wi
t
h
sl
o
w
char
gi
n
g
a
n
d
di
scha
r
g
i
n
g s
p
eed
s. C
ont
r
o
l
schem
e
of
Batter
y
is sh
ow
n in
Figu
r
e
5.
Evaluation Warning : The document was created with Spire.PDF for Python.
I
J
PED
S
I
S
SN
:
208
8-8
6
9
4
O
p
era
tion
an
d Co
n
t
ro
l
o
f
G
r
i
d
C
o
nn
ected
Hyb
r
id
AC/D
C Micro
g
rid
u
s
ing
…
(Ko
dand
a Ram
R B
P U
S
B)
19
9
Fi
gu
re
5.
C
o
nt
r
o
l
Sc
hem
e
for
B
a
t
t
e
ry
3.
3.
Inter
f
acing Converter
The
objective
of t
h
e interfacing c
o
nve
rter i
s
to
interface
bot
h the s
u
b grids i.e., AC
grid a
nd
DC
gri
d
. The m
a
jor r
o
l
e
of t
h
e
i
n
t
e
rfaci
ng c
o
nve
rt
er i
s
t
o
excha
n
ge p
o
we
r bet
w
ee
n t
h
e
AC
bu
s an
d D
C
bus.
Wh
en
op
erating
in
grid
tied
m
o
d
e
, th
e co
nv
erter s
u
p
p
l
i
e
s gi
ve
n act
i
v
e
a
n
d
reac
tive
power. T
h
e interfacing
con
v
e
r
t
e
r act
s
DC
/
A
C
i
n
ve
rt
er
whe
n
s
u
ppl
y
i
ng
p
o
w
er
f
r
om
DC
gri
d
t
o
A
C
gri
d
a
n
d act
s as
AC
/
D
C
re
ct
i
f
i
e
r
w
h
en
sup
p
l
ying
pow
er
f
r
o
m
A
C
gr
id
t
o
D
C
g
r
i
d
wh
en
ev
er r
e
qu
ir
ed
.
Th
e
in
ter
f
aci
n
g
conv
er
ter wo
rk
s
based
on
d
r
oo
p c
o
nt
r
o
l
[
1
1]
. T
h
e c
o
nt
r
o
l
schem
e
o
f
i
n
t
e
r
f
aci
n
g
c
o
nve
rt
er i
s
sh
o
w
n i
n
Fi
g
u
r
e
6.
The ad
vant
a
g
e
s
of i
n
t
e
rfa
ci
n
g
co
nve
rt
er ca
nn
ot
be real
i
zed by
ju
st
rel
y
ing
on t
h
e d
r
oo
p co
nt
rol
l
e
d
so
urces. Th
e interlin
k
i
ng
con
t
ro
l ch
alleng
es
has
t
o
be
care
f
ul
l
y
add
r
esse
d [1
2]
.
a)
Unl
i
k
e
uni
di
re
ct
i
onal
so
urces
, t
h
e i
n
t
e
rl
i
nki
ng c
o
n
v
e
r
t
e
rs
has t
o
m
a
nage bi
di
rect
i
o
nal
act
i
v
e an
d
react
i
v
e po
we
r
fl
o
w
s bet
w
ee
n
su
b gri
d
s.
b)
At an
y
o
n
e
in
stan
t, th
e i
n
terlin
k
i
n
g
conv
erters ha
ve t
w
o roles to play. T
h
ey appea
r
as l
o
ad to
one s
u
b g
r
i
d
whe
r
e ene
r
gy
i
s
abso
rbe
d
a
n
d ap
p
ear as s
o
urce to
othe
r grid
where e
n
ergy is
injecte
d
.
Fi
gu
re
6.
C
o
nt
r
o
l
Sc
hem
e
for
Int
e
r
f
aci
n
g
C
o
nve
rt
er
Tab
l
e 3
.
Param
e
ters
fo
r
th
e Hyb
r
id
Grid
Sy
m
b
ol
Description
Value
C
p
v
Capacitor across th
e solar panel
110 µF
L
1
I
nductor
for
the bo
ost conver
t
er
2.
5 m
H
C
d
Capacitor across th
e dc-link
4700 µF
L
2
Filtering inductor for the inverter
0.
43 m
H
R
2
E
quivalent r
e
sistance of the inver
t
er
0.
3 oh
m
C
2
Filtering capacitor
for the inverter
60 µF
L
3
I
nductor
for
the batter
y
conver
t
er
3 m
H
R
3
Resistance of
L3
0.
1 oh
m
F
Fr
equency
of AC
gr
id
60 Hz
f
s
Switching fr
equen
c
y
of power
conver
t
er
s
10 kHz
V
d
Rated DC bus voltage
400 V
V
ll
_
rm
s
Rated AC bus line
voltage (
r
m
s
value)
400 V
n1/n2
Ratio of the transform
e
r
2:1
C
Capacity
of Super
Capacitor
0.
5
F
4.
SIMULATION RESULTS
The
ope
rat
i
o
n
of
Gri
d
C
o
n
n
ect
ed
Hy
b
r
i
d
AC
/
D
C
M
i
cro
g
ri
d u
n
d
er
vari
ous
so
urc
e
and l
o
a
d
co
nd
itio
ns are
si
m
u
lated
to
v
e
rify th
e
reliab
ility.
DC RES power is sup
p
lied
d
i
rectly
to
th
e DC lo
ads an
d AC RES
p
o
wer
is sup
p
lied
d
i
rectly to
AC
lo
ad
s. Po
wer i
s
b
a
lan
c
ed
d
i
rectly b
y
th
e u
tility g
r
id
o
n
AC
b
u
s and
on
DC b
u
s
th
roug
h
in
terfaci
n
g
conv
erter.
The battery is
assum
e
d to be fully charge
d and ope
r
at
e
d
i
n
r
e
s
t
m
o
d
e
.
D
C
b
u
s
vol
t
age is control
l
ed and
main
tain
ed
b
y
u
tility g
r
id
throu
g
h
i
n
terfaci
ng con
v
e
rter. AC
bu
s
v
o
ltag
e
is
d
i
rectly m
a
in
tain
ed
b
y
u
tility
g
r
i
d
.
Th
e term
in
al vo
ltag
e
for ch
ang
e
in so
lar irrad
i
ati
o
n
is shown in
Figu
re
7. Op
tim
a
l
ter
m
in
al vo
ltag
e
Evaluation Warning : The document was created with Spire.PDF for Python.
I
S
SN
:
2
088
-86
94
I
J
PED
S
Vo
l.
5
,
No
.
2
,
O
c
t
o
b
e
r 201
4 :
1
95 –
20
2
20
0
o
f
PV
p
a
n
e
l is
o
b
t
ain
e
d b
y
u
s
in
g
t
h
e stan
d
a
rd
P&O algo
r
i
t
h
m
.
Th
e so
lar
i
r
r
a
d
i
an
ce w
a
s
set as 400W
/m
2
fr
o
m
0
.
0
s
to
0
.
1
s
, l
a
ter
it w
a
s lin
ear
ly in
cr
eased
to
1
000W
/
m
2
u
n
til 0
.
2
s
, k
e
p
t
co
nstan
t
to
0
.
3
s
,
d
e
creased
to
4
00W
/m
2
by
0
.
4s
an
d
kee
p
s
t
h
at
val
u
e
unt
i
l
fi
nal
t
i
m
e 0.5s.
The
sl
o
w
t
r
aci
n
g
s
p
ee
d
o
f
t
h
e
st
an
dar
d
P&
O
alg
o
rith
m
is o
p
ti
mized
b
y
u
s
i
n
g fu
el cell in
DC su
bg
ri
d
.
Fi
gu
re
8 a
n
d
Fi
gu
re
9 s
h
o
w
s t
h
e
cu
rve
s
of
t
h
e
PV
p
a
nel
p
o
w
er
o
u
t
p
ut
an
d s
o
l
a
r i
rra
di
at
i
o
n
r
e
sp
ectiv
ely. Th
e po
w
e
r
ou
tpu
t
v
a
r
i
es fro
m 4
.
85kW
t
o
13.5kW
, wh
ich
clo
s
ely f
o
llow
s
th
e so
lar
irr
a
d
i
atio
n
curve as
sum
i
ng the
fi
xed ambient tem
p
erature
.
Fi
gu
re
10
sh
o
w
s t
h
e
v
o
l
t
a
ge
an
d cu
rr
ent
re
spo
n
ses
o
n
AC
si
de
of i
n
t
e
rfa
ci
ng c
o
nve
rt
er
wi
t
h
a
fi
xe
d
DC
l
o
a
d
o
f
20
k
W
.
It
wa
s
obs
erve
d t
h
at
t
h
e
cur
r
ent
di
rect
i
o
n
o
f
i
n
t
e
rfaci
ng
co
n
v
ert
e
r
w
a
s re
verse
d
be
f
o
re
0
.
3s
an
d af
ter 0.4s.
Fi
gu
re
11 s
h
o
w
s t
h
e
vol
t
a
ge
and c
u
rre
nt
res
p
o
n
ses
o
n
AC
si
de o
f
i
n
t
e
r
f
ac
i
ng c
o
n
v
e
r
t
e
r
wi
t
h
va
ri
abl
e
D
C
lo
ad
f
r
o
m
2
0kW
to 40kW
at
0
.
2
5
s
w
ith
f
i
x
e
d
so
lar
i
r
r
a
d
i
atio
n at 75
0W
/m
2
. It can
be see
n
t
h
at
current
di
rect
i
o
n was r
e
verse
d
at
0.
2
5
s
.
Fi
gu
re 1
2
s
h
o
w
s t
h
e v
o
l
t
a
ge
resp
on
se at
D
C
bus
o
f
in
terfacin
g
co
nv
erter with
Fu
el cell sh
ows an
i
m
p
r
ov
ed tran
sien
t resp
on
se
wh
en
co
m
p
ared
Fi
g
u
re
13
with
ou
t
fu
el cell
un
d
e
r sam
e
co
nd
itio
n
s
Fi
gu
re
7.
Term
i
n
al
V
o
l
t
a
ge
of
PV
Pa
nel
Fi
gu
re 8.
P
o
we
r out
put
of
P
V
Panel
Figu
re
9.
S
o
lar
Ir
ra
diation
0
0.
05
0.
1
0.
15
0.
2
0.
25
0.
3
0.35
0.4
0.
4
5
0.
5
275
280
285
290
295
300
305
T
i
m
e
i
n
Sec (
s
)
V
o
lt
a
g
e
in
v
o
l
t
s
(
V
)
0
0.
1
0.
2
0.3
0.4
0.
5
0
2000
4000
6000
8000
10000
12000
14000
T
i
m
e
i
n
s
ec
(s
)
PV
Po
w
e
r
O
u
t
p
u
t
i
n
W
a
t
t
s (
W
)
0
0.1
0.2
0.3
0.
4
0.5
0
20
0
40
0
60
0
80
0
10
00
12
00
T
i
m
e
i
n
s
ec (
s
)
S
o
l
a
r I
rra
d
i
a
t
i
o
n
(W
/
m
2
)
Evaluation Warning : The document was created with Spire.PDF for Python.
I
J
PED
S
I
S
SN
:
208
8-8
6
9
4
O
p
era
tion
an
d Co
n
t
ro
l
o
f
G
r
i
d
C
o
nn
ected
Hyb
r
id
AC/D
C Micro
g
rid
u
s
ing
…
(Ko
dand
a Ram
R B
P U
S
B)
20
1
Fi
gu
re 1
0
. AC
si
de Vol
t
a
ge
a
n
d
C
u
rre
nt
of
t
h
e Int
e
r
f
aci
n
g
C
o
n
v
ert
e
r wi
t
h
Va
ri
abl
e
S
o
l
a
r
Ir
ra
di
at
i
on
a
n
d
C
onst
a
nt
DC
L
o
ad
Fi
gu
re 1
1
. AC
si
de Vol
t
a
ge
a
n
d
C
u
rre
nt
of
t
h
e Int
e
r
f
aci
n
g
C
o
n
v
ert
e
r wi
t
h
C
o
nst
a
nt
S
o
l
a
r
I
rra
di
at
i
o
n
a
n
d
Varia
b
le DC
L
o
ad
Figure 12. DC Bus
T
r
ansient
Resp
on
se with
Fu
el Cell
5.
CO
NCL
USI
O
N
A Hy
b
r
i
d
AC
/
D
C
M
i
cro
g
ri
d
i
s
pro
pos
ed a
nd c
o
m
p
rehe
n
s
i
v
el
y
st
udi
ed
i
n
t
h
i
s
pape
r.
The co
nt
r
o
l
st
rat
e
gi
es are
conci
s
el
y
st
at
ed t
o
m
a
i
n
t
a
i
n
st
abl
e
sy
st
em
operat
i
o
n
un
der
vari
ou
s l
o
ad an
d r
e
so
urce
conditions. T
h
e control strat
e
gies are ve
rified by
usi
ng
MATLAB/Sim
u
link. Va
rious
control m
e
thods are
i
n
co
rp
orat
e
d
t
o
ha
r
n
ess t
h
e
m
a
xim
u
m
po
wer
fr
om
R
E
S du
ri
n
g
gri
d
c
o
n
n
ect
ed
m
ode and
resem
b
l
e
s st
abl
e
ope
rat
i
o
n.
Th
e
In
terfacing
Conv
erter sh
ows st
ab
le
op
eration
d
u
ring
lo
ad
v
a
riation
s
. Ho
wev
e
r
th
ere will
be
som
e
pract
i
cal
l
i
m
i
t
a
t
i
ons, be
cause o
f
fast
a
nd c
ont
i
n
u
o
u
s
l
o
ad va
ri
at
i
o
n
s
. Eve
n
-t
h
o
u
g
h
,
t
h
e pr
op
ose
d
Hy
bri
d
g
r
i
d
redu
ces the p
r
o
cesses of
DC/AC
an
d
AC/DC con
v
e
rsi
o
n
s
in
an
ind
i
v
i
du
al sub
g
r
i
d
s, t
h
e th
eo
ry
is still
ch
allen
g
i
ng
in
th
e AC
d
o
m
in
ated
in
frastru
c
t
u
re. The Hy
b
r
i
d
AC/
D
C Microg
ri
d
h
a
s to
be tested
fo
r
v
a
riou
s
faul
t
s
on
s
u
b
g
r
i
ds a
nd t
h
ei
r e
f
fect
s o
n
t
h
e
ot
her
g
r
i
d
.
T
h
e
Hy
bri
d
AC
/
D
C
M
i
cro
g
ri
d
i
s
o
n
l
y
feasi
b
l
e
f
o
r
ne
w
co
nstru
c
tion
eith
er i
n
rem
o
te lo
catio
n or i
n
dustries.
0
0.
0
5
0.
1
0.
1
5
0.
2
0.
25
0.
3
0.
3
5
0.
4
0.
45
0.
5
-1
0
0
-5
0
0
50
10
0
T
i
m
e
in
Se
c (
s
)
V
o
la
tg
e
(
V
)
a
n
d
C
u
rr
e
n
t
(A
)
Vo
l
t
a
g
e
Cu
rr
en
t
0
0.
05
0.
1
0.
1
5
0.
2
0.
2
5
0.
3
0.
3
5
0.4
0.45
0.
5
-1
0
0
-5
0
0
50
10
0
T
i
m
e
i
n
s
ec (
s
)
V
o
l
t
a
ge
(
V
)
a
nd C
u
r
r
e
t
(
A
)
V
o
lta
g
e
Cu
r
r
e
n
t
0.
15
0.
2
0.2
5
0.3
0.
3
5
0.4
0.
4
5
38
0
38
5
39
0
39
5
40
0
40
5
41
0
Ti
m
e
i
n
se
c
(
s
)
Vo
l
t
a
g
e
(
V
)
Evaluation Warning : The document was created with Spire.PDF for Python.
I
S
SN
:
2
088
-86
94
I
J
PED
S
Vo
l.
5
,
No
.
2
,
O
c
t
o
b
e
r 201
4 :
1
95 –
20
2
20
2
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EE Trans. Industry
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BIOGRAP
HI
ES
OF AUTH
ORS
Kodanda Ram
R.
B.
P.
U.
S.
B.
rece
ived B
.
T
e
c
h
degree
from
J
N
T Univers
i
t
y
K
a
kinad
a
, Ind
i
a in
2010. He is
curr
ently
pursuing
M.Tech
in
Powe
r S
y
stems from K L University
,
Guntur, India.
He is hav
i
ng 2
years of
industrial exper
i
en
ce
in d
e
sign, manufactur
i
ng,
erection
and
commission
of LT Control P
a
nels from H
y
derabad. His spec
i
a
l f
i
elds
of in
ter
e
st inc
l
uded Sm
ar
t grids,
Microgrids, H
y
b
r
id Grids.
Dr.
M Venu Go
pala Rao
at present is
P
r
ofes
s
o
r
& Head, Depart
m
e
nt of Electri
c
a
l & Ele
c
troni
cs
Engineering, KL University
, Gun
t
ur, Andhra Prad
esh,
India. He o
b
tain
ed M.E in
Electrical Power
Engineering fro
m M S University
, B
a
roda, Ind
i
a in 1999
, M.Tech in Computer Science from
JNTU College
of Engineering, Kakinada, Indi
a in 2004 and
Doctoral Degr
ee in Electr
i
cal
&
Electronics Engineering from JNT University
, Hy
de
r
a
bad
,
India in 2009. He published more than
42 papers in
various National,
International Co
nferences and J
ournals. His r
e
search
interests
accum
u
la
te in
th
e are
a
of P
o
wer
Qualit
y,
S
m
art Ele
c
tri
c
Grid, Di
s
t
ribution S
y
s
t
e
m
and Elec
tri
cal
M
achines
.
Evaluation Warning : The document was created with Spire.PDF for Python.