Inter
national
J
our
nal
of
Electrical
and
Computer
Engineering
(IJECE)
V
ol.
7,
No.
1,
February
2017,
pp.
86
–
99
ISSN:
2088-8708
86
I
ns
t
it
u
t
e
o
f
A
d
v
a
nce
d
Eng
ine
e
r
i
ng
a
nd
S
cie
nce
w
w
w
.
i
a
e
s
j
o
u
r
n
a
l
.
c
o
m
Contr
ol
of
an
A
utonomous
Hybrid
Micr
ogrid
as
Ener
gy
Sour
ce
f
or
a
Small
Rural
V
illage
Am
´
erico
J
oaquim
Lampi
˜
ao
*
,
T
omonob
u
Senjyu
*
,
and
Atsushi
Y
ona
*
*
F
aculty
of
Engineering,
Department
of
Electrical
and
Electronics
Engineering
*
Uni
v
ersity
of
the
Ryuk
yus,
1
Senbaru,
Nishihara-cho,
Nakag
ami,
Okina
w
a,
903-0213,
Japan
Article
Inf
o
Article
history:
Recei
v
ed
Oct
7,
2016
Re
vised
Dec
11,
2016
Accepted
Dec
24,
2016
K
eyw
ord:
Microgrid
Utility
grid
Photo
v
oltaic
system
Battery
ener
gy
system
Po
wer
balance
ABSTRA
CT
No
w
adays,
the
e
xhaustion
of
electricity
po
wer
in
rural
areas
is
becoming
an
important
issue
for
man
y
African
Nations.
Moreo
v
er
,
challenges
include
the
high
cost
of
e
xtend-
ing
the
po
wer
grid
to
these
locations,
the
economic
health
of
the
utilities
and
lack
of
re
v
enue
in
impo
v
erished
vil
lages.
Numerous
ne
w
initiat
i
v
es
are
being
implemented
in
the
countries
some
of
them
co-financed
by
international
or
g
anizati
ons.
In
this
paper
,
the
h
ybrid
microgrid
is
carried
out
as
a
feasible
solution
for
a
small
rural
village.
A
model
of
h
ybrid
microgrid
consisting
of
combination
of
photo
v
oltaic
(PV)
panels
and
battery
ene
r
gy
storage
(BES)
and
a
control
system
for
managing
t
he
components
of
en-
tire
system
to
feed
the
village
as
local
load
is
proposed.
The
control
system
must
a
v
oid
the
interruptions
of
po
wer
deli
v
ered
to
the
consumers
(village)
and,
therefore,
good
quality
and
reliability
of
the
system
is
required.
The
PI
controllers
are
used
to
re
gu-
late
the
v
oltage
and
current
using
three-phase
dq
transformation,
whi
le
the
parameters
are
determined
using
Zie
gler
-Nichols
tuning
method.
The
ef
fecti
v
eness
of
the
pro-
posed
method
is
v
erified
by
simulation
results
gi
v
en
by
Matlab/SimPo
werSystems
R
en
vironment.
Copyright
c
2017
Institute
of
Advanced
Engineering
and
Science
.
All
rights
r
eserved.
Corresponding
A
uthor:
Am
´
erico
Joaquim
Lampi
˜
ao
Department
of
Electrical
and
Electronic
Engineering
Uni
v
ersity
of
the
Ryuk
yus
1
Senbaru,
Nishihara-cho,
Okina
w
a,
903-0213,
Japan
T
el:
+81-98-895-8686,
+258-84-438-3831
Email:
americo.lampiao@gmail.com
1.
INTR
ODUCTION
Ov
er
620
million
people
in
Africa
still
do
not
ha
v
e
access
to
the
electricity
[1].
As
kno
wn,
elec
tricity
is
an
essential
contrib
utor
to
the
well-being
of
people
and
a
k
e
y
point
of
economic
betterment
for
an
y
country
in
the
w
orld.
In
2001,
the
US
National
Academy
of
Engineers
(N
AE)
v
oted
”electrification”
as
the
most
significant
engineering
achie
v
ement
of
the
past
century
.
According
the
w
orldwide
calculation
of
electric
consumption
at
present,
approximately
1.4
billion
people
more
than
20
percent
population
all
o
v
er
the
w
orld
does
not
ha
v
e
access
to
electric
connection
and
mostly
li
v
e
in
rural
areas
in
Africa
[2].
The
biggest
challenges
surrounding
ener
gy
in
this
locations
is
the
high
cost
to
e
xtend
the
po
wer
grid
from
main
to
these
locations.
Ne
w
initiati
v
es
are
being
implemented
using
rene
w
able
ener
gy
source,
b
ut
impro
v
ements
are
still
required
[3].
In
this
paper
,
a
model
of
autonomous
h
ybrid
microgrid
supplying
a
small
rural
village
as
local
load
and
the
respecti
v
e
controller
is
proposed
to
demonstrate
their
feasibil
ity
solution
in
rural
villages.
The
h
ybrid
source
is
a
combined
PV
panels
and
Battery
storage,
connected
to
the
load
through
v
oltage
source
in
v
erter
(VSI),
filter
and
isolating
transformer
.
The
loads
are
typically
rural
such
as
mills,
w
ater
pumps
for
irrig
ation,
and
small
houses
with
one
or
tw
o
compartments.
The
households
mainly
use
the
fire
w
ood
for
cooking,
therefore,
small
po
wer
for
each
house
is
e
xpected.
The
use
of
PV
panels
as
rene
w
able
ener
gy
has
adv
antages
due
the
en
vironmental
re
gulation
protection,
b
ut
the
generated
po
wer
changes
according
the
temperature
and
solar
radiation
[4]-[6].
This
f
act
J
ournal
Homepage:
http://iaesjournal.com/online/inde
x.php/IJECE
I
ns
t
it
u
t
e
o
f
A
d
v
a
nce
d
Eng
ine
e
r
i
ng
a
nd
S
cie
nce
w
w
w
.
i
a
e
s
j
o
u
r
n
a
l
.
c
o
m
,
DOI:
10.11591/ijece.v7i1.12900
Evaluation Warning : The document was created with Spire.PDF for Python.
IJECE
ISSN:
2088-8708
87
generates
stability
,
reliability
and
po
wer
quality
problems
at
the
consumers
[7]-[11].
The
battery
is
used
to
o
v
ercome
the
intermittent
and
uncertain
of
the
photo
v
oltaic
(PV)
g
e
neration
[13].
The
PV
system
is
composed
by
PV
panels
and
DC/DC
boost
con
v
erter
.
In
order
to
maximize
the
ef
ficienc
y
of
the
PVs
and
maintain
the
v
oltage
at
the
DC-link,
a
combination
of
MPPT
(maximum
po
wer
point
tracking)
and
DC/DC
boost
con
v
erter
is
used.
The
MPPT
uses
an
algorithm
to
maintain
the
generated
po
wer
at
maximum
point
[11-13].
Depending
on
the
PV
generation
and
load
demand,
the
battery
may
operate
at
either
char
ging
or
dischar
ging
mode.
In
dischar
ging
mode,
the
battery
w
orks
as
po
wer
source
and
injects
po
wer
to
the
in
v
erter
and,
therefore
mak
es
balance
between
generation
and
load
po
wer
demand.
In
char
ge
mode,
the
battery
recei
v
es
the
po
wer
from
PV
system.
These
achie
v
ements
are
possible
by
using
a
DC/DC
bidirectional
con
v
erter
.
The
VSI
is
used
to
interf
ace
the
DC-side
with
A
C-side
and,
therefore,
to
con
v
ert
DC
current
to
A
C
with
appropriate
natural
frequenc
y
.
The
in
v
erter
operates
in
high
frequenc
y
(around
5-20
kHz),
and
causes
harmonic
distortions
in
output
current
[17]-[21],
therefore,
in
this
study
a
filter
harmonics
will
be
tak
en
into
account.
In
this
paper
,
an
isolating
transformer
rated
at
100
kV
A,
to
step-up
the
l
ine
v
oltage
from
230
V
to
380
V
,
is
used.
In
addition,
po
wer
supply
companies
demand
this
for
the
elimination
o
f
possible
zero
sequence
or
DC
components
in
the
generated
v
oltages
and
for
increased
protection
it
af
fords
[9].
This
f
act
can
be
used
as
an
adv
antage
since
the
transformer
can
form
part
of
a
filter
impedance
and
may
,
therefore,
reduce
the
undesired
harmonic
content
of
the
output
current.
Po
wer
quality
standards
for
connection
of
an
in
v
erter
to
the
load
are
still
under
de
v
elopment,
since
pre
viously
there
ha
v
e
been
fe
w
simi
lar
high
po
wer
electronic
applications.
In
this
study
the
important
aspect
of
po
wer
quality
is
harmonic
distortion.
General
requirements
for
harmonic
distortion
can
be
found
in
standards
IEEE
[1547.1-1547.8].
The
control
solution
proposed,
pro
vides
high
quality
of
current
deli
v
ered
to
the
consumers
and,
there-
fore,
high
po
wer
qu
a
lity
.
In
addition,
acti
v
e
and
reacti
v
e
po
wer
control
is
pro
vided.
The
choice
of
control
v
ariables
are
based
on
standards,
re
gulations
and
procedures
presented
in
scientific
publications.
PLL
(phase
lock
ed
loop)
and
PI
controllers
w
as
used
to
accomplish
the
po
wer
management
of
the
system
using
dq
syn-
chronous
reference.
The
parameters
w
as
determined
us
ing
Zie
gler
-Nichols
tuning
method.
Ov
er
the
years,
considerable
research
has
been
conducted
on
current
and
v
oltage
re
gulation
in
microgrids,
and
v
arious
ap-
proaches
ha
v
e
been
proposed.
In
this
paper
a
re
vie
w
of
the
latest
journal
and
conference
papers
related
to
the
control
in
microgrids
are
carried
out
to
demonstrate
the
v
alidity
of
the
proposed
method,
performed
using
MA
TLAB/
SimPo
wer
Systems
R
.
Simulation
results
demonstrate
the
ef
fecti
v
eness
of
proposed
controller
and,
therefore,
can
be
used
to
analyse
microgrids
connections.
The
rest
of
the
section
in
this
paper
is
or
g
anized
as
follo
ws:
In
Section
II,
the
proposed
model
is
presented
and
the
main
components
including
control
methodology
are
described.
In
Section
III
the
discussion
of
the
simulation
results
to
sho
w
the
ef
fecti
v
eness
of
the
proposed
system
is
presented.
Finally
,
conclusions
are
dra
wn
in
Section
IV
.
2.
RESEARCH
METHOD
The
methodology
adopted
in
this
study
,
is
proposing
the
schematic
configuration
of
the
model
to
be
implement
ed
and
sim
u
l
ated
using
Matlab/Simulink
en
vironment.
The
components
are
described
and
the
simulation
results
are
presented.
The
conclusion
is
based
on
the
presented
results.
Figure
1,
sho
ws
the
proposed
model,
and
the
description
are
presented
belo
w
.
2.1.
PV
System
The
PV
array
used
in
this
paper
acts
as
an
input
source
for
char
ging
the
battery
as
well
as
supplying
to
the
A
C
load
during
normal
conditions.
The
basic
equation
of
a
PV
panel
is
presented
in
[12].
T
able
2,
sho
ws
the
constant
v
alues
for
the
standard
stat
e
of
each
PV
panel
as
used
in
the
present
study
.
As
mentioned
in
pre
vie
w
chapters,
the
PV
generates
intermittent
po
wer
due
the
v
ariation
of
sun’
s
radiation
and
cell
temperature.
In
order
to
maximize
the
po
wer
and
maintain
the
v
oltage
in
DC-link
at
required
le
v
el
(400
V),
a
combined
MPPT
and
DC/DC
boost
con
v
erter
are
used.
The
MPPT
aims
at
using
an
algorithm
to
ensure
the
arr
ay
to
operate
at
the
maximum
po
wer
point
[6].
There
are
man
y
dif
ferent
MPPT
methods.
Perturbation
and
Observ
ation
(P&O)
method
is
used
most
widely
since
it
is
much
simpler
and
needs
fe
wer
measured
v
ariables
as
input.
In
this
study
P&O
w
as
used
and
performed
according
[4].
Contr
ol
of
an
A
utonomous
Hybrid
Micr
o
grid
as
Ener
gy
Sour
ce
for
a
Small
...
(Am
´
erico
J
.
Lampi
˜
ao)
Evaluation Warning : The document was created with Spire.PDF for Python.
88
ISSN:
2088-8708
B1
B1
B1
B1
B1
B1
R
1
L
1
PV_array
BESS
CB
m
DC
MPPT
Boost converter
3-Phase VSI
R
D
Cf
Clink
230 / 380V
DC
Rural Village
Ch = Chopper circuit
DC
AC
DC
DC
Bidirection DC/DC converter
Ch
House
1
House
3
House
2
House
4
House
5
House
6
50Hz, 380V,
±
100kVA
Scan:
Voltage
Current
Fig.
1.
Proposed
system
topology
.
2.2.
Battery
Ener
gy
Storage
System
(BESS)
The
battery
is
required
to
impro
v
e
the
system
performance
of
microgrid
and
mak
e
the
balance
between
the
genera
ted
po
wer
and
load
po
wer
demand
t
hroug
h
char
ge/dischar
ge
ener
gy
to
or
from
this
storage
[8].
In
this
paper
,
the
battery
model
is
Lithium-Ion
tak
en
from
the
MA
TLAB/Simulink
tools
with
a
nominal
v
oltage
of
310
V
.
The
initial
state
of
char
ge
(SOC)
of
the
model
can
be
set
according
to
the
need
of
the
simulation.
The
simulation
parameters
are
sho
wn
in
T
able
1.
The
battery
is
connected
at
the
DC-link
through
a
DC/DC
bidirectional
con
v
erter
.
The
objecti
v
e
of
this
con
v
erter
is
to
maintain
the
v
oltage
on
DC-link
(400
V)
and
to
operate
the
system
in
order
to
char
ge/dischar
ge
the
battery
according
the
dif
ferent
situations.
In
char
ge
mode
the
PV
generates
more
than
required
po
wer
and,
therefore,
the
e
xtra
po
wer
must
stored
in
the
battery
.
In
dischar
ge
mode,
the
PV
generates
less
than
required
po
wer
,
then
the
batt
ery
injects
po
wer
to
balance
the
generated
po
wer
with
load
po
wer
demand.
Figure
2,
sho
ws
the
schematic
configuration
of
bidirectional
con
v
ert
er
and
the
parameters
are
achie
v
ed
according
[11],
and
[15].
T
able
1.
P
arameters
of
the
Battery
model.
P
arameter
V
alue
Nominal
V
oltage
[V]
310
Rated
Capacity
[Ah]
8.2
Fully
Char
ged
V
oltage
[V]
360.836
Nominal
current
[A]
7.4157
Initial
State-of-Char
ge
[%]
80
2.3.
DC-b
us
dynamics
and
pr
otection
A
chopper
circuit
is
used
in
DC-link
to
dissipate
e
xcess
po
wer
during
f
ault
condition
or
o
v
er
v
oltage.
If
the
DC-link
v
oltage
e
xceeds
the
maximum
limit
(425
V),
the
DC-link
will
be
short-circuited
through
the
resistor
r
c
and
the
e
xcess
of
po
wer
will
be
dissipated
in
this
resist
or
,
then
the
DC-link
v
oltage
will
be
maintained.
A
common
capacitor
C
l
ink
is
installed
in
parallel
with
chopper
circuit
as
sho
wn
in
Figure
2.
In
this
study
,
the
v
alue
of
r
c
is
300
.
2.4.
In
v
erter
characteristics
The
role
of
po
wer
electronics
con
v
erter
is
v
ery
important
in
rene
w
able
ener
gy
systems
[11].
In
this
study
,
the
in
v
erter
is
set-up
in
accordance
with
the
circuit
sho
wn
in
Figure
2.
An
IGBT
six
pack
is
modelled
and
controlled
in
order
t
o
achie
v
e
the
required
obje
cti
v
es.
The
space-
v
ect
or
(SV)
po
wer
width
m
o
dul
ation
(PWM)
technique
is
used
to
produce
the
switching
control
signals
to
be
applied
at
three-phase
in
v
erter
.
IJECE
V
ol.
7,
No.
1,
February
2017:
86
–
99
Evaluation Warning : The document was created with Spire.PDF for Python.
IJECE
ISSN:
2088-8708
89
D
1
Q
p
C
link
Ip=Ipv
PV_array
PWM
MPPT
Ipv
Vpv
Vdc*
Vpv
Lp
Boost controller
Ih
Ic
Ie
L
b
Ib
Ib
PWM
Vdc*
Battery controller
B1
B1
B1
B1
B1
B1
Vdc
Ib
Ib*
AND
Qb
2
Qb
1
b1
b2
BESS
Q
6
Q
2
Q
1
Q
5
Q
4
Q
3
a
b
c
PI
1
Ird
Q
c
rc
R
1
L
1
R
2
L
2
C
f
R
D
LCL Filter
Winding Tr.
Chopper
Vdc
PI
2
Vdc
PI
3
I
cf
ON/OFF
O
O
O
O
n
Vc
f
<
AND
NOT
SOC
85%
CB
p
I
1
I
2
Load
(Village)
Fig.
2.
Detailed
system
configuration.
2.5.
Harmonics
filter
and
isolating
transf
ormer
In
this
study
,
a
LC
filter
combined
with
equi
v
alent
impedance
of
isolating
transformer
is
used
to
reduce
the
harmonics
distortions
in
output
in
v
erter
.
The
final
configuration
is
a
LCL
filter
which
the
components
are
determined
based
on
[17].
The
primary
object
i
v
e
of
isolating
transformer
is
to
step-up
the
line
v
oltage
from
230
V
to
380
V
(nominal
load
v
oltage).
The
parameters
are
presented
in
T
able
3.
2.6.
Load
characteristics
The
main
use
of
electricity
is
e
xpected
to
be
for
lights,
mills,
bars,
w
ater
pump
for
irrig
ation,
and
of
fice
in
village
center
.
The
load
v
ari
es
according
the
season
and
time.
F
or
e
xample,
during
the
rain
season
the
use
of
w
ater
pumps
are
not
required
for
irrig
ation,
and
therefore
the
load
po
wer
is
sm
all.
In
thi
s
s
tudy
,
the
estimated
maximum
load
po
wer
is
assumed
100
kV
A
and
the
line
v
oltage
and
natural
frequenc
y
is
380
V
and
50
Hz,
respecti
v
ely
.
T
able
2.
PV
panel
constants.
P
arameters
V
alue
P
arameters
V
alue
Short-circuit
current
I
sc
8.36
A
Number
of
cells
per
module
N
cel
l
s
54
Open
circuit
v
oltage
V
oc
33.20
V
Number
of
panels
in
series
N
s
14
V
oltage
at
maximum
po
wer
point
V
mpp
26.3
V
Number
of
panels
in
parallel
N
p
80
Current
at
maximum
po
wer
point
I
mpp
7.61
A
Diode
quality
f
actor
A
1.5
T
emperature
coef
ficient
of
I
sc
0.00502
Series
resistance
R
s
0.16
Elementary
char
ge
q
1.6
10
19
C
P
arallel
resistance
R
p
1010.60
Boltzmanns
constant
B
1.38
10
23
Ener
gy
g
ap
E
g
1.2
V
3.
CONTR
OL
OF
THE
SYSTEM
The
o
v
erall
control
structure
consists
of
a
DC-link
v
oltage
controller
and
a
line
current
controller
.
T
o
supply
a
line
current
with
lo
w
distortion,
the
connection
to
the
grid
is
made
by
an
A
C
filter
[17]
which
consists
of
combination
of
LC
and
equi
v
alent
impedance
of
isol
ating
transformer
used
to
boost
the
line
v
oltage
from
Contr
ol
of
an
A
utonomous
Hybrid
Micr
o
grid
as
Ener
gy
Sour
ce
for
a
Small
...
(Am
´
erico
J
.
Lampi
˜
ao)
Evaluation Warning : The document was created with Spire.PDF for Python.
90
ISSN:
2088-8708
230
V
to
380
V
.
The
final
configuration
is
LCL
filter
,
as
sho
wn
in
Figure
2.
The
control
is
made
in
dq
reference
and
PLL
is
used
to
re
gulate
the
system
frequenc
y
.
In
order
to
achie
v
e
good
performance
of
control
parameters,
the
poles
and
zeros
of
transfer
function
w
as
v
erified.
3.1.
Contr
ol
of
Boost
and
Bidir
ectional
DC/DC
con
v
erters
The
linearisation
of
boost
and
bidirectional
DC/DC
con
v
erters
are
analysed
and
presented
in
[8]
and
[15].
From
this
analysis,
the
v
oltage
and
current
transfer
functions
are
gi
v
en
by:
G
(
v
)
=
b
V
out
b
d
=
L
(1
D
)
2
V
in
s
+
R
V
in
R
LC
s
2
+
Ls
+
R
(1
D
)
2
(1)
G
(
i
)
=
b
I
in
b
d
=
V
in
(1
D
)
(2
+
R
C
s
)
R
LC
s
2
+
Ls
+
R
(1
D
)
2
(2)
where
V
out
is
reference
output
v
oltage
(400
V),
V
in
is
input
v
oltage,
I
in
is
the
induct
o
r
current,
L
is
inductor
,
C
is
common
capacitor
in
DC-link,
D
is
the
duty
c
ycle
and
R
is
the
equi
v
alent
load
resistor
.
The
details
about
this
task
is
presented
in
[11].
In
this
paper
,
the
equation
(1)
and
(2)
w
as
used
to
design
the
DC/DC
boost
controller
and
DC/DC
bidirectional
con
v
erter
.
As
mentioned
in
abo
v
e
chapters,
Zie
gler
-Nichols
tuning
method
w
as
used
to
achie
v
e
the
control
parameters.
Figures
4(b)
and
-(d),
sho
w
the
tuning
block
diagrams
of
v
oltage
and
current.
The
inductances
of
boost
and
bidirectional
con
v
erters
used
in
this
study
are
3
mH
and
1
mH,
respecti
v
ely
.
3.2.
DC-link
v
oltage
r
egulator
The
purpose
of
the
DC-link
v
oltage
controller
is
to
preserv
e
the
DC-link
v
oltage
at
its
reference
v
alue
(
V
dc
)
and
to
pro
vide
the
reference
po
wer
(
P
e
).
T
o
design
the
DC-link
v
oltage
re
gulator
,
the
follo
wing
assumptions
are
considered.
The
grid
v
oltage
amplitude
is
constant;
Using
rotary
ax
es
dq
,
the
grid
v
oltage
V
g
coincides
with
d
-axis;
The
unity
po
wer
f
actor
is
required,
then
the
displ
acement
between
the
grid
v
oltage
and
current
is
zero.
Their
q
-axis
components
are
also
zeros.
F
or
an
accurate
control
model,
it
w
as
made
a
linearisation
in
DC-side.
Figure
2,
sho
ws
the
schematic
config-
uration.
In
normal
condition
the
g
ate
of
IGBT
(
Q
c
)
recei
v
es
the
signal
zero,
meaning
that
the
chopper
circui
t
is
opened
and
no
current
is
flo
wing
through
dump-resistor
.
Ne
glecting
the
chopper
circuit,
the
DC
side
of
the
in
v
erter
can
be
described
as
follo
ws:
8
>
>
>
<
>
>
>
:
i
h
=
i
e
+
i
c
i
e
=
a
i
a
+
b
i
b
+
c
i
c
i
c
=
C
l
ink
v
dc
dt
P
h
=
i
h
v
dc
(3)
where
i
c
is
current
through
the
DC-link
capacitor
,
P
h
is
a
v
ailable
h
ybrid
acti
v
e
po
wer
at
s
pecific
solar
radiation
and
SOC,
C
l
ink
is
DC-link
capacitor
,
i
h
is
the
h
ybrid
current,
V
dc
is
v
oltage
in
DC-link,
i
e
is
the
current
deli
v
ered
to
the
in
v
erter
(which
is
a
function
of
the
line
currents
i
a
;
i
b
;
i
c
,
and
the
states
of
the
po
wer
-poles
a
;
b
;
c
(1:
’on’,
0:’of
f
’,
i
n
+
upper
pole,
i
n
lo
wer
pole
in
the
3-phase
VSI).
T
o
achie
v
e
steady
state
operation
the
supplied
DC
po
wer
of
the
P
h
and
the
A
C
po
wer
for
load
must
be
balanced.
The
DC
v
oltage
controller
gi
v
es
the
set
point
of
the
A
C
po
wer
.
Assuming,
in
this
paper
,
that
there
is
no
po
wer
losses
in
the
in
v
erter
,
if
only
acti
v
e
po
wer
is
to
be
injected
into
the
grid
(load):
(
P
e
P
g
=
3
V
g
I
g
=
3
2
V
g
d
I
g
d
Q
e
0
(4)
The
generated
h
ybrid
po
wer
and
the
link
capacitor
po
wer
are
e
xpressed
by
equations
(3)
and
(4),
respecti
v
ely:
P
hy
br
id
=
I
h
V
dc
(5)
IJECE
V
ol.
7,
No.
1,
February
2017:
86
–
99
Evaluation Warning : The document was created with Spire.PDF for Python.
IJECE
ISSN:
2088-8708
91
v
id
ω
L
i
d,ref
PI
4
Id,max
Id,min
Vdc*
ω
L
Viq,max
Viq,min
v
q
i
q,ref
Isq,max
Isq,min
Q,ref
v
d
∆
id
∆
i
q
i
d
i
q
Vdc
Q
v
iq
∆
Q
∆
v
SVPWM
dq
abc
abc
dq
abc
dq
v
d
v
q
i
d
i
q
Dump load
Controller
V
dc(max)
Vid,max
Vid,min
Vdc
Vdc
rd
IGBT
Clink
PLL
i
e
φ
Pcc
PI
6
PI
7
PI
5
~380V
50Hz
Fig.
3.
Control
scheme
of
the
grid-side
in
v
erter
.
P
capacitor
=
C
l
ink
V
dc
dV
dc
dt
(6)
The
VSI
losses
are
ne
glected,
then
the
follo
wing
relationship
is
v
erified:
P
g
r
id
=
P
hy
br
id
P
capacitor
(7)
F
ollo
wing
equations
(3)
to
(7),
the
relation
between
DC-link
v
oltage
and
the
grid
current
e
xpressed
in
rotary
axis
is
obtained:
V
dc
=
1
C
l
ink
s
(
I
h
3
2
V
g
d
V
dc
I
g
d
)
(8)
where
V
g
or
V
s
is
the
reference
phase
v
oltage
in
output
in
v
erter
(132.8
V).
The
DC-link
v
oltage
is
re
gulated
imposing
a
reference
in
the
acti
v
e
current
component
(
I
g
d
).
A
v
oltage
v
ariation
in
the
DC-link
is
compensated
by
changing
the
A
C
line
acti
v
e
currents,
in
such
a
w
ay
that
t
h
e
DC-link
is
k
ept
at
the
est
ablished
v
alue
(400
V).
The
PIs
are
used
as
re
gulators
and
their
parameters
are
achie
v
ed
by
using
Zie
gler
-Nichols
tuning
method.
The
DC-link
v
oltage
control
loop
is
presented
in
Figure
4(b).
3.3.
VSI
and
Grid
curr
ent
contr
oller
The
output
current
controller
consists
of
a
model
based
on
LCL
filter
configuration,
as
sho
wn
in
Figure
2.
According
Kirchhof
f
’
s
rules,
we
obtain
the
equations:
!
v
i
!
i
1
R
1
L
1
d
!
i
1
dt
!
i
c
R
d
!
v
cf
=
0
(9)
!
v
s
+
!
i
2
R
2
+
L
2
d
!
i
2
dt
!
i
c
R
d
!
v
cf
=
0
(10)
!
i
c
=
!
i
1
!
i
2
(11)
The
equi
v
alent
equations
of
(9),
(10)
and
(11)
can
be
described
as:
d
dt
!
i
1
=
(
R
d
+
R
1
)
(
L
1
)
!
i
1
+
R
d
L
1
!
i
2
+
1
L
1
!
v
cf
+
1
L
1
!
v
i
(12)
d
dt
!
i
2
=
(
R
d
+
R
2
)
(
L
2
)
!
i
2
+
R
d
L
2
!
i
1
+
1
L
2
!
v
cf
1
L
2
!
v
s
(13)
Contr
ol
of
an
A
utonomous
Hybrid
Micr
o
grid
as
Ener
gy
Sour
ce
for
a
Small
...
(Am
´
erico
J
.
Lampi
˜
ao)
Evaluation Warning : The document was created with Spire.PDF for Python.
92
ISSN:
2088-8708
d
dt
!
v
cf
=
1
C
f
(
!
i
1
!
i
2
)
(14)
where,
!
i
1
=
[
i
1
a
i
1
b
i
1
c
]
t
is
the
output
current
at
filter
,
!
i
2
=
[
i
2
a
i
2
b
i
2
c
]
t
is
the
current
injected
to
the
grid;
!
v
cf
=
[
v
cf
a
v
cf
b
v
cf
c
]
t
is
the
v
oltage
in
capacitor
C
f
.
The
control
system
is
made
by
using
v
oltage
and
current
measurements.
In
order
to
reduce
the
number
of
measurement
sensors,
and
therefore,
minimizing
the
cost
of
project,
we
consider
only
tw
o
sensors
to
detect
v
oltage
and
current.
The
basic
control
principles
used
in
this
paper
are
generally
based
on
the
decoupled
current
control
presented
in
[17],
and
[18].
The
three-phase
v
oltage
on
load
b
us
is
measured
and
transformed
into
a
dq
reference
frame
(
v
d
and
v
q
).
The
three-phase
current
fl
o
wing
between
the
loads
and
the
in
v
erter
is
measured
and
transformed
to
i
d
and
i
q
.
W
ith
the
comparisons
of
the
dq
components
to
their
respecti
v
e
references
,
the
resulting
errors
are
sent
to
the
PI
controllers
to
generate
the
required
output
v
oltage
of
the
in
v
erter
.
In
order
to
f
acilitate
the
equation
analysis,
man
y
researches
mak
e
approximations
such
that
the
output
current
in
v
erter
is
assumed
equal
with
the
output
current
at
the
filter
(
i
1
i
2
),
because
the
current
i
c
is
v
ery
small
[20]-[21].
Considering
this
approximations,
the
filter
is
analysed
as
R
L
and
the
parameters
are
the
summation
of
filter
impedance
and
equi
v
alent
internal
impedance
of
the
transformer
(
R
t
=
R
1
+
R
2
,
and
L
t
=
L
1
+
L
2
).
In
this
paper
,
this
assumptions
are
used
to
achie
v
e
the
decoupled
equations:
d
dt
!
i
1
dq
=
"
R
t
L
t
!
!
R
t
L
t
#
!
i
1
dq
1
L
1
!
v
s
dq
+
1
L
1
!
v
i
dq
(15)
where,
!
is
the
system
frequenc
y
in
r
ad=s
.
From
(15)
is
obtained:
V
i
d
=
(
R
t
+
L
t
s
)
I
1
d
+
V
s
d
!
L
t
I
1
q
(16)
V
i
q
=
(
R
t
+
L
t
s
)
I
1
q
+
V
s
q
+
!
L
t
I
1
d
(17)
In
equation
(16)
and
(17),
considering:
V
"
d
=
(
R
t
+
L
t
s
)
I
1
d
(18)
V
"
q
=
(
R
t
+
L
t
s
)
I
1
q
(19)
The
equi
v
alent
equation
become:
V
i
d
=
V
"
d
+
V
s
d
!
L
t
I
1
q
(20)
V
i
q
=
V
"
q
+
V
s
q
+
!
L
t
I
1
q
(21)
The
plant
is
a
first
order
system
with
transfer
function
G
(
s
)
=
I
1
dq
(
s
)
V
i
dq
(
s
)
=
1
R
t
+
sL
t
(22)
The
PI
transfer
function
without
deri
v
ati
v
e
action
is
gi
v
en
by:
T
s
=
K
p
+
K
i
s
=
K
p
(1
+
1
T
i
s
)
(23)
Where
T
i
=
K
p
K
i
is
inte
gral
time
constant
or
reset
tim
e,
K
p
and
K
i
is
proportional
and
inte
gral
g
ains,
respec-
ti
v
ely
.
The
goal
of
tuning
method
is
to
find
the
proper
g
ains
in
order
to
achie
v
e
the
required
reference
v
alues.
The
block
diagrams
of
control
loops
are
sho
wn
in
Figure
4(a)
and
-(c).
4.
RESUL
T
AND
AN
AL
YSIS
In
order
to
demonstrate
the
ef
fecti
v
eness
of
the
proposed
control
strate
gy
,
a
combined
PV
and
BESS
(h
ybrid)
connected
to
the
load
through
three-phase
VSI
w
as
set
up
and
simulated
under
three
dif
ferent
scenarios
using
sampling
time
20
s
and
time
domain
from
0
to
0.55
s.
The
temperature
is
assumed
constant
25
o
C
and
sudden
changes
of
solar
radiation
w
as
implemented
as
input
of
PV
panels.
The
initial
SOC
is
80
%
in
all
scenarios.
a)
Case
Study
1:
This
scenario
aims
to
confirm
the
functionali
ties
of
PV
and
BESS
under
solar
v
ariations
to
supply
the
load
rated
with
po
wer
100
kW
.
The
simulation
is
carried
out
in
sequence
as
follo
ws:
IJECE
V
ol.
7,
No.
1,
February
2017:
86
–
99
Evaluation Warning : The document was created with Spire.PDF for Python.
IJECE
ISSN:
2088-8708
93
System transfer function
1
i
dref /
i
qref
1
1/R
t
Lt
Rt
s
Kp
1+Ti S
Ti
id /
iq
PI-Controller
V
d’
/
V
q’
V
d
/
V
q
V
dcref
1
1
C
link
.S
Kp
1+Ti S
Ti
PI-Controller
System transfer function
V
dcref
1
Gv(s)
Equation (7)
Kp
1+Ti
S
Ti
Vdc
PI-Controller
PWM + converter
System transfer function
I
Lref
1
Gi(s)
Equation (8)
Kp
1+Ti
S
Ti
I
L
PI-Controller
PWM + converter
2
3
Vgd
Vdc
I
h
PWM
(a)
(b)
(c)
(d)
PWM + converter
Fig.
4.
Block
diagrams
of
control
loops.
T
able
3.
Grid
parameters
and
control
g
ains
P
arameters
V
alue
P
arameters
V
alue
Filter
inductance
L
1
265
H
Switching
frequenc
y
f
s
20
kHz
Filter
resistance
R
1
40
m
Natural
frequenc
y
f
50
Hz
Filter
resistance
R
d
100
m
Frequenc
y
modulation
P
W
M
10
kHz
Filter
capacitor
C
f
300
C
PI
4
=
P
I
5
[
K
p
;
K
i
]
[2.1,
253]
T
ransformer
inductance
L
2
185
H
PI
6
=
P
I
7
[
K
p
;
K
i
]
[0.004,
0.21]
T
ransformer
resistance
R
2
25
m
PI
1
[
K
p
;
K
i
]
[0.0006,
0.13]
Dc-link
capacitor
C
l
ink
470
C
PI
2
[
K
p
;
K
i
]
[0.0002,
0.18]
Peak
load
po
wer
P
l
oad
100
kW
PI
3
[
K
p
;
K
i
]
[0.0004,
0.21]
At
t
=0.0
s,
the
simulation
starts
when
the
solar
radiation
is
maximum
(1
kW/m
2
),
therefore,
the
PV
panels
are
generating
m
ore
than
required
load
po
wer
.
In
this
case,
the
e
xcess
po
wer
is
stored
in
battery
.
The
maximum
po
wer
injected
to
the
in
v
erter
is
115.15
kW
,
means
that
100.0
kW
is
for
load
and
15.15
kW
is
total
loss
in
in
v
erter
,
filter
,
transformer
and
lines.
In
that
period
the
battery
is
recei
ving
po
wer
and
therefore,
the
SOC
rises
gradually
(char
ging
mode).
At
t
=0.2
s,
the
solar
radiation
drops
suddenly
until
0.5
kW/m
2
and
the
PV
panels
start
to
generate
l
ess
than
required
po
wer
.
In
that
moment,
the
battery
detects
the
problem
and
starts
to
inject
the
po
wer
to
the
in
v
erter
in
order
to
balance
the
generation
with
the
load
demand.
Therefore,
the
battery
starts
to
dischar
ge
and
the
SOC
decreases
gradually
.
At
t
=0.4
s,
the
solar
radiation
suddenly
rises
until
(1
kW/m
2
)
and
the
PV
panels
starts
ag
ain
to
generate
more
than
required
po
wer
,
then
the
battery
changes
from
dischar
ge
to
char
ge
mode.
During
this
process,
the
DC-link
v
oltage,
po
wer
injected
in
in
v
erter
,
v
oltage,
and
load
current
are
maintained
at
400
V
,
115.15
kW
,
380
V
and
300
A,
respecti
v
ely
as
the
graphics
sho
wn
in
Figure
5.
b)
Case
Study
2:
This
scenario
aims
to
confirm
the
functionalities
of
PV
and
BESS
under
load
v
ariation
and
solar
radiation
at
0.5
kW/m
2
.
The
simulation
is
carried
out
in
sequence
as
follo
ws:
At
t
=0.0
s,
the
simulation
starts
when
the
load
is
70.0
kW
solar
radiation
at
0.5
kW/m
2
,
therefore,
the
PV
panels
are
generating
more
than
required
load
po
wer
.
In
this
case,
the
e
xcess
po
wer
is
stored
in
battery
.
The
system
is
injecting
in
in
v
erter
80.0
kW
,
meaning
that
an
amount
of
po
wer
is
to
compensate
the
losses.
In
that
period
the
battery
is
recei
ving
po
wer
and
therefore,
the
SOC
is
increasing
gradually
.
At
t
=0.2
s,
the
load
increases
until
100
kW
,
then
in
that
time
the
load
po
wer
becomes
more
than
generated
po
wer
.
In
order
to
compensate
the
generation,
the
battery
starts
to
inject
the
po
wer
to
mak
e
balance.
While
the
batte
ry
is
injecting
po
wer
,
the
battery
is
being
dischar
ged
and
therefore,
the
SOC
is
gradually
decreasing.
At
t
=0.4
s,
the
load
po
wer
suddenly
drops
then
the
battery
changes
from
dischar
ge
to
char
ge
mode
in
order
to
store
the
e
xcess
generated
po
wer
.
Figure
6(a),
sho
ws
the
beha
viour
of
solar
radiation,
-(b)
sho
ws
the
v
oltage
on
DC-link,
-(c)
sho
ws
the
battery
current,
-(d)
sho
ws
the
SOC,
-(e)
sho
ws
the
acti
v
e
po
wer
injected
in
in
v
erter
,
-(e)
and
-(f)
sho
w
the
v
oltage
and
current
in
load
b
us.
c)
Case
Study
3:
This
scenario
aims
to
confirm
the
functionalities
of
PV
and
BESS
under
f
aults,
load
and
solar
v
ariations.
The
simulation
is
carried
out
in
sequence
as
follo
ws:
At
t
=0.0
s,
the
simulation
starts
when
the
all
load
is
connected
100.0
kW
and
the
solar
radiation
is
maximum.
The
PV
panels
are
generating
more
than
required
po
wer
.
Therefore
the
e
xcess
po
wer
is
store
d
in
battery
.
At
t
=0.1
s,
an
instantaneous
f
ault
occur
on
load
b
us
and
transients
are
observ
ed.
When
the
f
ault
is
remo
v
ed,
the
system
becomes
stable.
At
t
=0.15
s,
some
loads
are
disconnected
from
the
grid
and,
therefore,
the
po
wer
injected
in
in
v
erter
reduces
until
70
kW
.
At
t
=0.2
s,
a
similar
f
ault
occur
in
load
b
us
and
the
transients
are
observ
ed
ag
ain.
When
the
f
ault
is
remo
v
ed
the
system
becomes
stable.
At
t
=0.25
s,
all
load
is
connect
ed
(100
kW)
and
therefore
the
injected
po
wer
increases
Contr
ol
of
an
A
utonomous
Hybrid
Micr
o
grid
as
Ener
gy
Sour
ce
for
a
Small
...
(Am
´
erico
J
.
Lampi
˜
ao)
Evaluation Warning : The document was created with Spire.PDF for Python.
94
ISSN:
2088-8708
too.
At
t
=0.28
s,
the
solar
radiation
drops
until
0.5
kW/m
2
and
the
battery
starts
to
inject
po
wer
to
compensate
the
generated
po
wer
according
the
load
demand.
At
t
=0.38
s
and
0.48
s,
inst
antaneous
f
aults
occur
on
load
b
us
and
transients
are
v
erified.
When
the
v
oltage
on
DC-link
e
xceeds
425
V
,
the
chopper
circuit
detects
and
an
amount
of
po
wer
is
suppressed
by
dump-load
resistor
in
order
to
rapidly
balance
the
v
oltage.
Figure
7,
sho
ws
the
graphics
under
study
.
This
re
sults
demonstrate
that
the
system
is
controllable
and
the
v
oltage
and
current
deli
v
ered
to
the
consumers
ha
v
e
good
quality
.
Figure
7(f),
sho
ws
the
total
harmonic
distortion
(THD=3.94
%
).
5.
CONCLUSION
This
paper
has
proposed
a
model
of
autonomous
h
ybrid
microgrid
po
wering
through
in
v
erter
a
small
rural
village
and
the
design
of
respecti
v
e
controller
to
re
gulate
the
instantaneous
output
v
oltage.
The
graphs
obtained
during
the
simulations,
e
xplain
in
detail
the
system’
s
v
ersatility
in
dif
ferent
operating
condition.
The
system
pro
v
es
ho
w
a
rene
w
able
source
of
ener
gy
such
as
PV
panels
can
w
ork
together
with
battery
in
microgrid
to
po
wer
local
loads
.
Battery
storage
impro
v
es
the
reliability
of
the
system
by
o
v
ercom
ing
the
PV
generation
in
order
to
balance
with
the
load
demand.
The
battery
storage
acts
as
DC
load
during
char
ge
mode,
and
as
DC
source
during
dis
char
ge
mode.
The
system
w
as
accurately
modelled
using
Matlab/simulink
and
the
parameters
ha
v
e
been
chosen
according
the
standards
and
methodologi
es
presented
in
literatures.
The
simulation
results
demonstrate
the
ef
fecti
v
eness
of
the
proposed
model
and
respecti
v
e
control
methodology
.
A
CKNO
WLEDGEMENT
The
authors
are
really
e
xpressing
their
gratitude
to
the
Senjyu’
s
Lab
.
members
at
the
Department
of
Electrical
and
Electronic
Engineering,
for
their
contrib
utions.
REFERENCES
[1]
UN
Document
s
Gathering
a
body
of
global
agreements,
Chapter
7
of
the
charter
of
the
United
Nations
Signed
in
San
Francisco,
California
on
June,
1945.
http://www
.un-documents.net/k-002988.htm.
[2]
A.
H.
Khan,
et
al.,
”A
Noble
Design
of
a
DC
Micro
Grid
for
Rural
Area
in
Bangladesh,
”
International
Journal
of
T
echnology
Enhancements
and
Emer
ging
Engineering
Research
,
v
ol.
3,
pp.
19-26,
2015.
[3]
C.
M
arnay
,
et
al.,
”Optimal
T
echnology
Selection
and
Operation
of
Commercial-Building
Microgrids,
”
IEEE
T
ransactions
on
Po
wer
Systems
,
v
ol.
23,
no.
3,
pp.
975-982,
August
2008.
[4]
M.
G.
V
illalv
a,
et
al.,
”Comprehensi
v
e
Approach
to
Modeling
and
Simulation
of
Photo
v
oltaic
Arrays,
”
IEEE
T
ransactions
on
Po
wer
Electronics
,
v
ol.
24,
no.
5,
pp.
1198-1208,
May
2009.
[5]
S.
Rahman
and
H.
A.
Rahman,
”Use
of
Photo
v
oltaics
in
Microgrid
as
Ener
gy
Source
and
Control
Method
using
MA
TLAB/Simulink,
”
International
Journal
of
Electrical
and
Computer
Engineering
(IJECE)
,
v
ol.
6,
no.
2,
pp.
851-858,
April
2016.
[6]
G.
Sekar
and
T
.
Anita,
”Design
and
implementation
of
solar
PV
for
po
wer
quality
enhancement
in
Three-
phase
four
-wire
distrib
ution
system,
”
Journal
of
Electrical
Engineering
and
T
echnology
(JEET)
,
pp.
75-82,
2015.
http://dx.doi.or
g/10.5370/JEET
.2015.10.1.075.
[7]
Z.
Miao,
et
al.,
”An
SOC
based
battery
management
system
for
microgrids,
”
IEEE
T
ransactions
on
Smart
Grid
,
v
ol.
5,
no.
2,
pp.
966-973,
2014.
[8]
M.
Miyagi
,
et
al.,
”Uninterruptible
smart
house
equipped
with
the
phase
synchronization
control
system,
”
International
Journal
of
Electrical
Po
wer
and
Ener
gy
Systems,
Else
vier
,
v
ol.
63,
pp.
302-310,
2014.
[9]
R.
Majumder
,
et
al.,
”Control
and
protection
of
a
microgrid
connected
to
utility
through
back-to-back
con
v
erters,
”
Electric
Po
wer
Systems
Research,
Else
vier
,
v
ol.
81,
pp.
1424-1435,
2011.
[10]
M.
Prodano
vic,
and
T
.
C.
Green,
”Control
and
filter
design
of
three-phase
in
v
erters
for
high
po
wer
quality
grid
connection,
”
IEEE
T
ransactions
on
Po
wer
Electronics
,
v
ol.
18,
no.
1,
pp.
373-2003,
January
2003.
[11]
R.
Erickson,
and
D.
Maksmo
vic,
”Fundamentals
of
po
wer
electronics,
”
Kluwer
Academic
Publishers
,
v
ol.
2,
pp.
5-350,
2000.
[12]
H.
Bellia,
et
al.,
”A
detailed
modeling
of
photo
v
oltaic
module
u
s
ing
Matlab,
”
NRIA
G
Journal
of
Astron-
omy
and
Geoph
ysics
,
v
ol.
3,
pp.
53-61,
May
2014.
[13]
H.
Matayoshi,
et
al.,
”Uninterrupted
smart
house
equipped
with
a
single-phase
dq-transformation
system,
”
Journal
of
Rene
w
able
and
Sustainable
Ener
gy
,
v
ol.
8,
025101
(106)
doi:10.1063/1.4942781.
IJECE
V
ol.
7,
No.
1,
February
2017:
86
–
99
Evaluation Warning : The document was created with Spire.PDF for Python.
IJECE
ISSN:
2088-8708
95
[14]
A.
P
anda,
et
al.,
”A
single
phase
photo
v
oltaic
in
v
erter
control
for
grid
connected
system,
”
Sadhana,
Indian
Academy
of
Sciences
,
v
ol.
41,
no.
1,
pp.
15-30,
January
2010.
[15]
M.
Go
wda,
et
al.,
”Moddeling
of
Buck
DC-DC
con
v
erter
using
Simulink,
”
International
Journal
of
Inno-
v
ati
v
e
Research
in
Science,
Engineering
and
T
echnology
,
v
ol.
3,
pp.
14965-14975,
July
2014.
[16]
N.
W
ang,
at
al.,
”Battery
ener
gy
storage
system
information
modeling
based
on
IEC
61850,
”
Journal
of
Po
wer
and
Ener
gy
Engineering
,
v
ol.
2,
pp.
233-238,
April
2014.
[17]
M.
Liserre,
et
al.,
”Design
and
Control
of
an
LCL-Filter
-Based
Three-Phase
Acti
v
e
Rectifier
,
”
IEEE
T
ransactions
on
Industry
Applications
,
v
ol.
41,
no.
5,
pp.
1281-1291,
2005.
[18]
T
.
Raju,
and
P
.
R.
Reddy
,
”A
No
v
el
Control
Algorithm
for
an
Adapti
v
e
Hysteresis
Band
Current
Con-
trolled
Shunt
Acti
v
e
Po
wer
Filter
,
”
International
Refereed
Journal
of
Engineering
and
Science
(IRJES)
,
pp.
10-16,
2014.
[19]
S.
Bhat,
et
al.,
”Ef
fect
of
P
arasitic
Elements
on
the
Performance
of
Buck-Boost
Con
v
erter
for
PV
Sys-
tems,
”
International
Journal
of
Electrical
and
Computer
Engineering
(IJECE)
,
v
ol.
4,
no.
6,
pp.
831-836,
December
2014.
[20]
X.
Bao,
et
al.,
”Feedback
Linearization
Control
of
Photo
v
oltaic
in
v
erter
with
LCL
Filter
,
”
2012
IEEE
7th
International
Po
wer
Electronics
and
Motion
Control
Conference
-
ECCE
Asia
,
pp.
2197-2201,
June
2012.
[21]
M.
G.
M.
Abdolrasol,
and
S.
Mekhilef,
”Three
phase
grid
connected
anti-islanding
controller
based
on
distrib
uted
generation
interconnecti
o
n,
”
2010
IEEE
International
Conference
on
Po
wer
and
Ener
gy
(PECon2010)
,
pp.
717-722,
2010.
BIOGRAPHIES
OF
A
UTHORS
Am
´
erico
J
oaquim
Lampi
˜
ao
recei
v
ed
his
B.S.
de
gree
in
electr
ical
engineering
from
Uni
v
ersidade
Eduardo
Mondlane
at
Mozambique
in
2009.
Currently
,
he
is
pursuing
Master
de
gree
in
electrical
engineering
at
Graduate
School
of
Engineering
and
Science
at
Uni
v
ersity
of
the
Ryuk
yus,
Japan.
Besides,
he
is
a
junior
Engineer
at
the
Electricidade
de
Moc
¸
ambique
(EDM),
the
national
electricity
utility
in
Mozambique.
His
researches
interests
include
po
wer
electronics,
smart
grid,
microgrids,
v
oltage
stability
,
po
wer
protection
and
electricity
mark
ets.
He
is
af
filiated
with
Order
of
Engineers
of
Mozambique,
and
with
IEEE
as
student
member
.
T
omonob
u
Senjyu
recei
v
ed
the
B.S.
and
M.S.
de
grees
in
electrical
engineering
from
Uni
v
ersity
of
the
Ryuk
yus
Japan
and
the
Ph.D.
de
gree
in
electrical
engineering
from
Nago
ya
Uni
v
ersity
,
Japan.
Since
1988,
he
has
been
with
the
Department
of
Electrical
and
Electronic
Engi
neering,
F
aculty
of
Engineering,
Uni
v
ersity
of
the
Ryuk
yus,
where
he
is
currently
w
orking
as
a
Professor
.
His
current
research
interests
include
stability
of
ac
machines,
adv
anced
control
of
electrical
machines,
po
wer
electronics,
rene
w
able
ener
gy
and
smart
grid.
Atsushi
Y
ona
recei
v
ed
the
B.S.,
M.S.
and
the
Ph.D.
de
gree
from
the
Uni
v
ersity
of
the
Ryuk
yus,
Okina
w
a,
Japan,
in
2006,
2008
and
2010,
respect
i
v
ely
,
all
in
electrical
engineering.
In
2008,
he
joined
the
Uni
v
ersity
of
the
Ryuk
yus,
where
he
is
no
w
a
Assistant
P
rofessor
at
the
Department
of
Electrical
and
Electronic
Engineering.
His
research
interests
include
the
rene
w
able
ener
gy
,
fore-
casting
techniques
and
optimal
planning.
Dr
.
Y
ona
is
a
member
of
the
Institution
of
Electrical
Engineers
of
Japan.
Contr
ol
of
an
A
utonomous
Hybrid
Micr
o
grid
as
Ener
gy
Sour
ce
for
a
Small
...
(Am
´
erico
J
.
Lampi
˜
ao)
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