Internati
o
nal
Journal of P
o
wer Elect
roni
cs an
d
Drive
S
y
ste
m
(I
JPE
D
S)
Vol.
4, No. 4, Decem
ber
2014, pp. 547~
556
I
S
SN
: 208
8-8
6
9
4
5
47
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
Application of Distribution Powe
r Electron
ic T
r
ans
f
ormer f
o
r
Medium Voltage
P
r
a
s
ha
nt
K
u
ma
r
Departementof
Electrical
Eng
i
n
eer
ing
,
AMGOI, Shivaji University
, Kolh
apur Maharashtra-41611
2, India
Article Info
A
B
STRAC
T
Article histo
r
y:
Received
J
u
n 18, 2013
Rev
i
sed
Sep
18
, 20
13
Accepte
d Oct 2, 2013
I
n
t
h
i
s
p
a
p
e
r
a
d
i
s
t
r
i
b
u
t
i
o
n
p
o
w
e
r
e
l
e
c
t
r
o
n
i
c
t
r
a
n
s
f
o
r
m
e
r
(
D
P
E
T
)
f
o
r
feeding cr
iti
cal l
o
ads is presented. The PE based transform
e
r is a
m
u
lti-por
t
converter th
at can conn
ect to
medium
voltage lev
e
ls on
the p
r
imar
y
side.
Bidirection
a
l po
wer flow is pro
v
ided to
the each module. The presented
structure
consists of three stag
es: an i
nput stage, an isolation stage, and
an
output stage. The input curr
ent is
sinusoidal, and it conver
t
s the high AC
input voltage to
low DC voltag
e
s. Th
e isolated
DC/DC converters are then
connected
to th
e DC links
and
provide g
a
lvan
ic isolation b
e
tw
een
the HV
and LV sides. F
i
nally
,
a three-p
h
ase
inver
t
er g
e
nerates the AC
output with
the desir
e
d
amplitude and f
r
equenc
y
.
The pr
oposed DPET is extremely
modular and
can be
extended
for
diffe
rent vo
ltag
e
and power levels. It
performs ty
pical functions an
d has a
dvanta
g
es
s
u
ch as
power factor
correc
tion
,
el
im
ination of
volt
a
g
e
sa
g and
swell, and r
e
duction
of voltag
e
flick
e
r in
load side. Also in
compar
ison to
conventional transfor
mers, it has
lower weight, l
o
wer volum
e and elim
inat
es
neces
s
i
t
y
for tox
i
c die
l
ec
tri
c
coolan
ts the
DPET p
e
rform
ance
is verif
i
ed
in M
A
TLAB sim
u
lati
on.
Keyword:
Co
nv
erter
DC link
Distribution power electronic
trans
f
o
r
m
e
r (D
PET)
Isol
at
i
o
n t
r
a
n
s
f
orm
e
r
PW
M
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
:
Pras
hant
K
u
m
a
r,
Depa
rtem
ent of Elect
ri
cal
E
n
gi
nee
r
i
n
g,
Ashok
rao
Mane Group
o
f
In
stitu
tes,
K
o
l
h
apur
, Mahar
a
sh
t
r
a-4
161
12
,
In
d
i
a.
Em
a
il: p
r
ash
a
nt2
6
8
5
@g
m
a
i
l
.co
m
1.
INTRODUCTION
Distrib
u
tion
p
o
we
r Electro
ni
c Trans
f
o
r
m
e
r (DPE
T) is
a new type of transform
e
r, which realizes
v
o
ltag
e
tran
sform
a
t
i
o
n
an
d
p
e
rfo
r
m
s
p
o
w
er q
u
a
lity fu
nctio
n
s
th
rou
g
h
m
o
d
e
rn
po
wer electron
i
c co
nv
ert
e
rs. In
fact
, D
P
ET
pr
ovi
des a f
u
nda
m
e
nt
al
l
y
di
ffer
e
nt
an
d m
o
re com
p
l
e
t
e
appr
o
ach i
n
t
r
a
n
s
f
o
r
m
e
r desi
g
n
by
usi
n
g
p
o
wer electron
i
cs on
th
e
prim
ary an
d
seco
nd
ary sid
e
s o
f
th
e t
r
an
sfo
r
m
e
r.
W
ith
t
h
e aid
o
f
m
u
ltilev
e
l
conve
r
ters on
the line side,
a high
voltage
interface wit
h
the utility
Alte
rnating C
u
rrent (AC) syste
m
i
s
pr
o
v
i
d
e
d
, m
eanw
h
i
l
e
wi
t
h
t
h
e ai
d
of
hi
g
h
p
e
rf
orm
a
nce3
p
h
ase
i
n
vert
e
r
on
t
h
e l
o
a
d
s
i
de,
a l
o
w
v
o
l
t
a
ge
interface with
cons
um
er applications is produce
d
.
T
h
ese new
type of
tra
n
sform
e
rs
ha
ve
been introduc
ed to
el
im
i
n
at
e t
h
e
d
r
aw
bac
k
s
of
co
nve
nt
i
o
nal
c
o
p
p
er
- a
n
d
-
i
r
on
b
a
sed t
r
a
n
s
f
o
r
m
e
rs
[1]
-
[
6]
.
Th
ose
hea
v
y
an
d
bul
k
y
t
r
ans
f
o
r
m
e
rs are fu
n
d
am
ent
a
l
co
m
pone
nt
s i
n
po
wer
di
st
r
i
but
i
o
n sy
st
em
s. They
are re
l
a
t
i
v
el
y
i
n
expe
nsi
v
e
,
h
i
gh
ly reliab
l
e, and
fairly effi
cien
t.
Howev
e
r, th
ey
h
a
v
e
so
m
e
d
i
sadv
an
tag
e
s such
as
h
eav
y
weig
h
t
, sen
s
itiv
i
t
y to
h
a
rm
o
n
i
cs, vo
ltag
e
dr
o
p
u
n
d
er l
o
ad,
(re
q
u
i
r
ed
)
pr
ot
ect
i
on
fr
o
m
sy
st
em
di
srupt
i
o
ns a
n
d
o
v
erl
o
ad
, p
r
ot
ect
i
on
of sy
st
e
m
fro
m
pr
o
b
l
e
m
s
ari
s
ing
at
o
r
bey
o
n
d
t
h
e t
r
a
n
s
f
o
r
m
e
r, en
vi
r
onm
ent
a
l
co
n
cerns
re
gar
d
i
n
g m
i
neral
oi
l
,
an
d
lowperform
ance under
dc-offset load
unbalance.T
h
ses
d
isadvanta
g
es are
b
ecom
i
ng i
n
cre
a
si
ngl
y
im
port
a
nt
as
p
o
wer qu
ality b
e
co
m
e
s
m
o
re o
f
a co
n
c
ern
[1
].
Fo
r
realizatio
n
of PET, d
i
ffe
ren
t
top
o
l
o
g
i
es i
n
literatu
re
have
been
pre
s
ent
e
d [
1
]
-
[
6]
.
R
e
ference [
2
]
appl
i
e
s an A
C
/
A
C
buc
k co
nve
rt
er t
o
re
d
u
ce i
nput
v
o
l
t
a
ge t
o
a
lo
wer on
e. In
t
h
is stru
ct
u
r
e
for work
ing
at med
i
u
m
v
o
ltag
e
lev
e
ls, it n
eed
s a lo
t o
f
series tied
p
o
w
er
Evaluation Warning : The document was created with Spire.PDF for Python.
I
S
SN
:
2
088
-86
94
I
J
PED
S
Vo
l.
4
,
No
.
4
,
D
ecem
b
er
2
014
:
54
7 – 556
54
8
swi
t
c
hes,
w
h
i
c
h are
di
ffi
cul
t
t
o
co
nt
r
o
l
an
d
st
ress fact
or
w
oul
d
be
hi
g
h
.
Al
s
o
t
h
e
st
r
u
ct
ure s
u
f
f
e
r
s l
a
ck
of
m
a
gnet
i
c
i
s
ol
at
i
on a
n
d
d
o
es
n’
t
perf
o
r
m
pow
er fact
or c
o
r
r
e
c
t
i
on. C
onsi
d
e
r
i
n
g ab
o
v
e p
o
i
n
t
s
, t
h
e
AC
/
A
C
buc
k
c
o
n
v
e
r
t
e
r
i
s
n
o
t
p
r
a
c
t
i
c
a
l
f
o
r
m
e
d
i
u
m
v
o
l
t
a
g
e
a
p
p
l
i
c
a
t
i
o
n
s
[
1
]
.
A
n
o
t
h
e
r
a
p
p
r
o
a
c
h
t
o
r
e
a
l
i
z
e
D
P
E
T
structure has been introduce
d
in [3
]
-
[
4]
. T
h
ey
use t
h
e co
n
cept
of a
hi
g
h
-
fre
que
ncy
AC
/
A
C
l
i
nk, t
e
rm
ed as
electronic tra
n
sform
e
r. I
n
this
Appro
a
c
h
; t
h
e li
ne sid
e
AC
w
a
ve
f
o
r
m
is
m
o
d
u
lated
to
a h
i
gh
f
r
eq
ue
n
c
y sq
uar
e
w
a
ve and
p
a
ss
ed
th
ro
u
g
h
a
H
F
tran
s
f
o
r
m
e
r
and
again
w
i
th a s
y
nch
r
o
n
o
u
s co
n
v
er
ter
,
it is de
m
o
d
u
lated
t
o
AC
f
o
r
m
. This m
e
t
h
o
d
s
o
l
v
es
t
h
e
lack
o
f
m
a
g
n
etic iso
l
atio
n
b
u
t
y
e
t it d
o
es
n
’
t
p
e
r
f
o
r
m
p
o
w
e
r f
a
c
t
o
r
co
rr
ec
ti
o
n
o
r
i
s
n
o
t
a
p
p
l
i
c
a
b
l
e
f
o
r
h
i
g
h
v
o
l
t
a
g
e
a
p
p
l
i
c
a
t
i
o
n
s
.
R
e
f
e
r
e
n
c
e
[
1
]
a
n
d
[5
]
propose a
s
t
r
u
c
t
u
r
e
b
a
s
e
d
on
i
nput
s
e
r
i
es
o
u
t
p
ut
-
p
a
r
allel co
n
n
e
c
t
i
o
n
of c
o
n
v
e
r
t
er
s t
o
r
e
a
l
i
ze DP
ET s
t
ru
ctur
e. T
h
o
s
e s
c
he
mes ar
e ex
tre
m
el
y
m
o
d
u
lar
and
p
e
r
f
o
r
m
p
o
w
e
r
q
u
alit
y f
u
nct
i
o
n
s. H
o
w
e
ver
t
h
e
y
use hi
g
h
f
r
eq
u
e
n
c
y s
w
i
t
chi
n
g
,
so
the
y
hav
e
lo
w
ef
f
i
cie
n
c
y
. Al
s
o
all the ser
i
es co
nver
t
er
s sh
o
u
ld
w
o
r
k
si
m
u
lta
neo
u
s
l
y
w
h
ic
h
t
h
is f
a
c
t
r
e
d
u
ce
s the a
v
ailab
ilit
y
and r
e
liab
ilit
y o
f
t
h
e s
y
s
t
e
m
.
In
[6
] a
n
e
w top
o
l
o
g
y
b
a
sed
on
b
a
ck-to-b
a
ck d
i
od
e- clam
p
m
u
l
tilev
e
l co
nv
erter h
a
s
b
e
en in
trodu
ced.
It p
e
rform
s
d
i
fferen
t
p
o
wer qu
ality
fu
n
c
tio
n
s
an
d
p
r
ep
ares mag
n
e
tic iso
l
atio
n. Ho
wev
e
r fo
r
h
i
gh
voltage a
p
plications, it has a limitation on the nu
m
b
er of voltage
levels. Because, by increasi
ng the
vol
t
a
ge l
e
vel
s
bey
o
nd
fi
ve
o
r
si
x, t
h
e
pr
act
i
cal
pr
obl
em
s such a
s
pac
k
a
g
i
ng
pr
o
b
l
e
m
s
and
p
h
y
s
i
cal
l
a
y
out
d
i
fficu
lties appear.
This pa
pe
r pre
s
ents a new t
o
pology of
DPET
ba
sed on
m
u
ltilevel
conve
rter. For balancing
DC
bus
es, a
new
a
n
d
si
m
p
l
e
cont
rol
m
e
t
hod
ha
s bee
n
p
r
ese
n
t
e
d.
I
n
c
o
m
p
ari
s
on
wi
t
h
[1]
a
n
d
[
5
]
,
i
t
has
bet
t
e
r
efficiency a
nd
its reliability h
a
s bee
n
im
proved. T
h
e st
ructure is e
x
trem
ely
m
odular
a
n
d
there is
no lim
itation
for vo
ltag
e
levels. Th
e proposed
DPET p
e
rform
s
p
o
w
er
qu
ality fu
n
c
tions b
e
sid
e
th
e
vo
ltag
e
red
u
c
ti
on
. It
corrects the
input
Powe
r
factor, re
gulates t
h
e l
o
ad volta
ge, a
n
d acts s
u
c
h
as
VAR c
o
m
p
ensator. It
can als
o
g
r
eatly allev
i
ate th
e power
qu
ality su
scep
ti
b
ility o
f
th
e
d
i
strib
u
tion
lev
e
l tran
sform
e
rs o
n
bo
th
sou
r
ce and
load sides.
2.
SYSTE
M
CO
NFIG
U
RATI
O
N
A ne
w DPET t
o
p
o
l
o
gy
i
s
pr
o
pos
ed
. As sh
o
w
n i
n
Fi
g
u
r
e 1, i
t
i
s
const
r
u
c
t
e
d base
d on
m
odul
es and a
comm
on dc link,
whic
h is
use
d
to t
r
ans
f
er energy
betwee
n
ports a
nd is
ola
t
e all ports
from
each other. In this
bi
di
rect
i
o
nal
t
o
pol
ogy
, eac
h p
o
rt
can
be co
ns
i
d
ere
d
as an i
n
put
or o
u
t
put
.
Each m
odul
e c
onsi
s
t
s
of t
h
ree
m
a
i
n
part
s,
i
n
cl
u
d
i
n
g m
odul
at
o
r
,
d
e
m
odul
at
o
r
,
an
d
hi
g
h
f
r
e
que
n
c
y
i
s
ol
at
i
on t
r
a
n
sf
orm
e
r (
H
F
I
T).
The
m
odul
at
or i
s
a DC
/
A
C
c
o
n
v
ert
e
r
an
d t
h
e
dem
odul
at
o
r
i
s
an
AC
/
A
C
co
nve
rt
er;
bo
t
h
wi
t
h
bi
di
re
ct
i
onal
p
o
w
er
fl
o
w
capability. Ea
ch m
odule
ope
r
ates indepe
ndently and
can
t
r
ans
f
er
power betwee
n ports. These ports
ca
n have
many differe
n
t cha
r
acteristics, s
u
ch as
v
o
l
t
a
ge l
e
vel
,
f
r
e
q
u
e
ncy
,
ph
ase a
n
gl
e, a
n
d
wave
f
o
rm
. As
a re
su
l
t
,
PE
T
can sat
i
s
fy
al
m
o
st
any
ki
nd
of a
p
pl
i
cat
i
o
n
,
w
h
i
c
h a
r
e de
si
red i
n
p
o
we
r
el
ect
roni
c c
o
nve
rsi
o
n sy
st
e
m
s and
meet
future ne
eds of
electricity networks.
Fi
gu
re 1.
Pro
p
o
s
e
d
DP
ET
I
n
t
h
is p
a
p
e
r
,
a m
o
d
u
lar s
t
ruct
u
r
e
b
a
se
d
on the class
i
f
i
catio
n s
y
s
t
e
m
gi
v
e
n i
n
[
1
1
]
is pr
o
p
o
s
ed
(
F
ig
u
r
e
2
)
. The
m
a
i
n
A
C
/D
C
co
n
v
er
ter is p
l
ace
d
in
s
w
itch
sh
o
w
n
in
Fi
g
u
r
e
2
is co
m
p
o
s
ed
o
f
“N”
Half
-
b
r
i
d
g
e
(
H
B
)
c
e
lls co
n
n
ec
ted in s
e
r
i
e
s
on the pr
im
ar
y s
i
d
e
and “
N
” DC
/D
C con
v
er
te
r
s
co
n
n
e
c
t
e
d in s
e
r
i
es o
n
th
e
s
e
c
o
nd
a
r
y s
i
d
e
. The DP
ET s
t
ructu
r
e c
a
n
a
l
s
o
b
e
r
e
ar
ra
nge
d
t
o
s
upply di
fferent t
y
pes
of elect
ric loa
d
s
sim
u
ltaneously
.
Evaluation Warning : The document was created with Spire.PDF for Python.
I
J
PED
S
I
S
SN
:
208
8-8
6
9
4
App
lica
tio
n o
f
D
i
strib
u
tion
Po
wer Electron
i
c Tran
sf
o
r
m
e
r
fo
r Med
i
um
Volta
g
e
(Pra
shant Ku
ma
r)
54
9
F
i
g
u
r
e
2.
D
P
E
T
s
c
h
e
m
a
t
i
c
di
a
g
r
a
m
This capa
b
ility is shown i
n
F
i
gure 2
whe
r
e
3 seri
es
- output cells will supply a three-phase voltage
so
urce inv
e
rter an
d
t
h
e rem
a
i
n
ing
cells will su
pp
ly ind
i
v
i
du
al lo
ads. In
t
h
is case, th
e i
n
p
u
t
p
o
wer fed
to
th
e
seri
es Hal
f
-b
ri
dge
s i
n
swi
t
c
h wo
ul
d
be
di
ffe
rent
. T
h
e
r
ef
or
e, th
e HB rectifier shou
ld
m
a
in
tain
v
o
ltag
e
b
a
lan
c
e
am
ong
t
h
e
pri
m
ary
DC
l
i
nks
an
d co
rrect
t
h
e i
n
p
u
t
p
o
w
er
fact
or
.
An
ot
he
r chal
l
e
ngi
ng i
ssue i
s
rel
a
t
e
d
t
o
t
h
e
equal
l
o
ad
-c
ur
r
e
nt
sha
r
i
n
g am
on
g t
h
e seri
es
cel
l
s
. A
very
s
m
al
l
m
i
sm
at
ch am
ong t
h
e se
r
i
es cel
l
s
can ca
use a
large c
u
rre
nt
deviation am
ong them
. This
problem
,
in pr
actice, is intensified
by
the
non-ideality of
series
cells.
2.
1.
Input Stage
P
o
wer
The input sta
g
e is a m
u
ltilevel HB recti
f
ier,
wh
ich
is p
a
rticu
l
arly
attractiv
e in
hig
h
v
o
ltag
e
ap
p
lication
s
. Th
is stru
ctu
r
e is ex
trem
ely
m
o
d
u
l
ar, it h
a
s a si
m
p
le p
h
y
sical layo
u
t
, and
it n
eed
s th
e l
o
west
n
u
m
b
e
r
o
f
co
m
p
on
en
ts in
co
m
p
ariso
n
with o
t
h
e
r m
u
ltilev
e
l co
nv
erters. Th
i
s
p
a
p
e
r fo
cuses on
ly on
th
e sin
g
l
e-
pha
se HB
rect
i
f
i
e
r.
The t
h
ree
-
pha
se st
ru
cture is ob
tain
ed
b
y
asso
ciation
o
f
th
ree Sing
le-ph
a
se HB
co
nv
erters
connected i
n
a star configuration.
F
u
rt
h
e
rm
ore, bi
di
re
ct
i
onal
p
o
we
r
fl
ow ca
n be
real
i
zed fr
o
m
t
h
e
b
i
d
i
rection
a
l
rectifier b
y
t
u
rn
ing
o
f
f th
e t
o
p switch
e
s
i
n
all Hal
f
-b
ri
d
g
e
s.
In th
is
work, a sing
le-ph
a
se
b
i
d
i
rection
a
l
HB co
nv
erter is an
alyzed
, and th
e resu
lts
ca
n be us
ed either in a
bidi
rec
tional converte
r or a
three-phase syste
m
. In Figure 2, th
ere are “
N
” series-c
onnected Half-bri
dge cells and each cell can generat
e
th
ree
v
o
ltag
e
lev
e
ls on
t
h
e
AC sid
e
: 0
,
+V
C
and
−
V
C
, wh
er
e V
C
i
s
t
h
e de
si
red DC
-l
i
n
k vol
t
a
ge
.
T
h
us, usi
n
g
“N”
Hal
f
-
b
ri
d
g
e
cel
l
s
, a m
a
xi
m
u
m
of
2N+
1
di
ffe
rent
v
o
l
t
a
ge
l
e
vel
s
are
obt
ai
ne
d t
o
sy
nt
hesi
ze
V
an
or
V
1
(AC term
in
al v
o
ltag
e
):
N
i
hi
in
V
V
1
(1)
V
hi
=h
i
V
ci
,
i=
1,
2.
.
.
N
(2)
Whe
r
e V
hi
, V
Ci
an
d
h
i
are the AC term
in
al
v
o
ltag
e
, th
e cap
acito
r
vo
ltage an
d
t
h
e swit
ch
ing
fu
n
c
ti
o
n
o
f
ith
H
a
lf
-br
i
dg
e, r
e
sp
ectiv
ely. A
p
p
l
yin
g
K
i
r
c
hh
of
f’
s v
o
lta
g
e
law (KVL) at th
e in
pu
t
v
o
ltag
e
l
o
op
yield
s
:
V
in
=
V
an
+ L
b
(d
l
in
/dt)
(3)
Wh
ere
Vin
i
s
th
e inpu
t vo
ltag
e
,
Iin
is th
e inp
u
t
cu
rren
t, and
Lb
is th
e inp
u
t
indu
ctan
ce
wh
ich
is u
s
ed
t
o
s
h
ape
t
h
e i
n
put
c
u
rre
nt
.
Ap
pl
y
i
ng
Ki
rc
h
h
o
ff
’s c
u
rre
nt law (
K
CL
) f
o
r e
ach cell leads
to:
I
hi
=
h
i
I
in
,
i= 1,
. .
.
,
N
(4)
Whe
r
e I
hi
i
s
t
h
e out
put
cu
rr
e
n
t
of i
t
h
Hal
f
-b
ri
d
g
e an
d i
s
a fu
nct
i
on
of t
h
e i
n
put
cu
rr
e
n
t
.
Eq
uat
i
o
n (
1
)
–
(
4
)
descri
be a l
i
n
e
a
r t
i
m
e
vary
i
ng (LT
V
) sy
st
em
wi
t
h
one i
n
put
(
V
i
n
) an
d
N+ 1 st
at
es (
V
C1
to
V
CN
and
I
in
). T
h
e
HB
co
n
t
ro
ller sh
ou
l
d
d
e
term
i
n
e
th
e
switch
i
ng
fun
c
tion
s
, h
1
to
h
N
, in ord
e
r
to
ach
iev
e
t
h
e
co
n
t
ro
l
go
als.
2.
2.
Iso
lat
i
on St
age
The second pa
rt of the DPE
T
st
ructure (Fi
g
ure 2) contains the
isolated DC/DC converters. T
h
ese
conve
r
ters a
r
e
connected to t
h
e
HB
convert
e
r links a
n
d provi
de a
highly
stable DC i
n
terface
on the L
V
side.
In t
h
e a
b
ove t
o
pology, se
ve
ral isolated conve
rters ca
n
be series
on the LV si
de to
increase t
h
e
powe
r
Evaluation Warning : The document was created with Spire.PDF for Python.
I
S
SN
:
2
088
-86
94
I
J
PED
S
Vo
l.
4
,
No
.
4
,
D
ecem
b
er
2
014
:
54
7 – 556
55
0
capaci
t
y
. H
o
w
e
ver
,
t
h
e
seri
es
cel
l
s
sh
oul
d s
h
are t
h
e l
o
a
d
-c
ur
rent
e
q
ual
l
y
and
u
n
i
f
orm
l
y
,
i
n
or
de
r t
o
a
c
hi
eve
id
en
tical op
eratin
g
co
nd
ition
s
. Th
is fact is
also
im
p
o
r
tan
t
fro
m
a th
erm
a
l v
i
ewpo
in
t.
In
t
h
e iso
l
atio
n stag
e,
d
i
fferent k
i
nd
s
o
f
DC/
D
C conv
erters
can
b
e
u
tilized
. Nev
e
rt
h
e
less, we
u
s
e a
bri
dge c
o
nve
rt
er,
whi
c
h i
s
t
h
e
best
i
n
t
e
r
m
s of effi
ci
en
cy
and
v
o
l
t
a
ge
st
ress.
Am
ong
t
h
e b
r
i
d
ge t
o
po
l
ogi
es
,
th
e zero
vo
ltage switch
e
d
conv
erter
h
a
s a b
e
tter p
e
rform
a
n
ce th
an
altern
ativ
e to
po
log
i
es. All switch
e
s,
in
th
is
to
po
log
y
, are tu
rn
ed
on
in
the ZVS cond
itio
n, and
th
e
turn
off losses are co
n
t
ro
lled
b
y
th
e series cap
acito
rs.
Furt
herm
ore, i
n
t
h
i
s
DPET a
ppl
i
cat
i
o
n, we
need
go
o
d
vol
t
a
ge i
s
ol
at
i
on b
e
t
w
een t
h
e H
V
and LV si
des
,
whi
c
h
corres
ponds to high leaka
g
e
inductance
. Therefore it appe
ars m
o
re r
easonable to use a zero
voltage s
w
itche
d
co
nv
erter as opp
o
s
ed to
o
t
h
e
r
altern
ativ
es t
h
at
require a
low
leakage i
n
duct
a
nce tra
n
s
f
ormer.
2.
3.
Outp
ut Stage
The
out
put sta
g
e usually contains a si
ngl
e-phase
or t
h
ree-phase
volta
ge s
o
urce inve
rter that is
con
n
ect
ed
t
o
t
h
e
DC
b
u
s a
n
d
gene
rat
e
s
t
h
e AC
o
u
t
p
ut
wi
t
h
t
h
e
des
i
red am
pl
i
t
ude
an
d f
r
e
que
ncy
.
Th
e
DC bus
m
a
y also c
o
nnect
dire
ctly to a DC l
o
ad
o
r
to
a co
m
b
in
ation
o
f
AC
and
DC lo
ad
s.
3.
CO
NTR
O
L S
T
RATEG
Y F
O
R
PET
Am
ong m
u
ltilevel converters, the
bri
dge
topology
seem
s pa
rticularly attractive in
high
voltage
ap
p
lication
s
. Th
e m
a
j
o
r
d
r
awb
ack
o
f
th
e t
o
po
log
y
is its
requ
irem
en
t to
isolated
DC
sources wh
en
it is
used
as
an
inv
e
rter. No
twith
stan
d
i
n
g
, wh
en
ev
er it is u
s
ed
as an
activ
e rectifier,
th
e to
po
log
y
is ev
en
m
o
re attractiv
e
because of the
available distinct DC
links
feeding differe
n
t loads
.
Howe
ver in
rectification m
ode there is
p
o
s
sib
ility o
f
in
stab
ility in
b
a
lan
c
in
g
of DC
b
u
s
es, an
d
consequ
e
n
tly th
e co
llap
s
ing
o
f
switch
e
s and
conv
erter.
An
ot
he
r
pa
ra
m
e
t
e
r whi
c
h s
h
o
u
l
d
be c
ons
i
d
ere
d
, i
n
st
u
dy o
f
rectifiers, relates to
power fact
or correction
cap
ab
ility and
th
e redu
ctio
n of inpu
t h
a
rm
o
n
i
cs.
In literature
various c
ont
rol
m
e
thods
for s
o
lving
t
h
e i
n
stability proble
m
of DC
buse
s ha
ve
bee
n
pr
o
pose
d
.
U
n
f
o
rt
unat
e
l
y
m
o
st
of t
h
ese m
e
t
hods
ha
ve
bee
n
l
i
m
i
t
e
d t
o
t
w
o
seri
es Hal
f
-
b
ri
dge
s beca
use
o
f
t
h
e
cont
rol com
p
lexities, but in t
h
is pa
per a novel and si
m
p
le
m
e
thod for c
ont
rolling n ha
lf -bridges has
been
pr
o
pose
d
.
The
pr
o
pose
d
m
e
t
hod
g
u
ara
n
t
ees t
h
e v
o
l
t
a
ge
bal
a
nci
n
g o
f
DC
b
u
ses e
v
en t
h
o
u
gh t
h
e u
n
e
q
u
a
l
l
o
ads
have
been c
o
nnected to disti
n
ct DC
buses.
In addition it program
s
the input
curre
nt to be in sinusoi
d
a
l
form
,
in
ph
ase or
o
t
her
p
h
a
se ang
l
es with
t
h
e inpu
t
v
o
ltag
e
.
In Fi
g
u
r
e 3(a
)
, t
h
e co
nt
r
o
l
bl
oc
k di
ag
ram
of HB
rect
i
f
i
e
r has bee
n
sh
ow
n. It
co
nt
ai
ns t
w
o m
a
i
n
parts: analo
g
c
ont
roller an
d s
o
ft
ware
section. T
h
e analog
cont
roller pre
p
ares th
e v
ital Q sig
n
a
l fo
r so
ft
ware
sectio
n
.
Th
en th
e so
ft
ware sectio
n
will d
e
fi
ne th
e
b
e
st switch
i
ng
co
mm
an
d
s
fo
r
Half-b
ridg
es.
In Fi
g
u
r
e 3(
b)
,
t
h
e det
a
i
l
schem
e
of anal
og c
ont
rol
l
e
r has
b
een sh
ow
n. It
c
ont
ai
n
s
a PI co
nt
r
o
l
l
e
r fo
r
regu
latin
g
t
h
e t
o
tal v
o
ltag
e
of
d
i
stin
ct DC
b
u
ses to
th
e
d
e
sired
referen
ce
valu
e of nV
C
. N
e
xt
,
t
h
e o
u
t
p
ut
of PI
co
n
t
ro
ller is mu
ltip
lied
b
y
th
e
m
a
in
s v
o
ltage wav
e
form
to
g
e
n
e
rate th
e d
e
sired
re
ference o
f
in
pu
t curren
t
.
Sin
ce th
e m
a
in
s v
o
ltag
e
is sinu
so
i
d
al, th
e referen
ce
v
a
lu
e
o
f
i
n
p
u
t
cu
rre
nt
i
s
al
so si
nus
oi
dal
.
Fo
r speci
fy
i
n
g
the phase a
n
gle betwee
n i
n
put voltage
and c
u
rrent, a tim
e
d
e
lay is u
s
ed
between
i
n
pu
t
vo
ltag
e
an
d m
u
l
tip
lier.
W
i
t
h
o
u
t
i
t
,
t
h
e
i
n
p
u
t
cu
rre
nt
a
n
d
v
o
l
t
a
ge
w
o
ul
d
be i
n
pha
se
.
Fi
gu
re
3(a
)
.
C
o
nt
r
o
l
bl
ock
di
a
g
ram
Fi
gu
re
3(b
)
.
A
n
al
o
g
con
t
r
o
l
l
e
r u
s
e
d
i
n
Fi
g
u
r
e
3(a)_
A h
y
steresis cu
rren
t co
m
p
arato
r
is e
m
p
l
o
y
ed
in
th
e in
n
e
r co
n
t
ro
l loo
p
. It p
r
og
ram
s
th
e i
n
pu
t cu
rren
t
to
be in sinu
soid
al fo
rm
an
d i
n
p
h
a
se
with
t
h
e m
a
in
s
voltage. This
com
p
arator gene
rate
s
the Q
signal for
the
soft
ware
section.
This
signal
has t
h
e following m
eaning:
Q
=
0, I
i
n*
+h
<Iin
Evaluation Warning : The document was created with Spire.PDF for Python.
I
J
PED
S
I
S
SN
:
208
8-8
6
9
4
App
lica
tio
n o
f
D
i
strib
u
tion
Po
wer Electron
i
c Tran
sf
o
r
m
e
r
fo
r Med
i
um
Volta
g
e
(Pra
shant Ku
ma
r)
55
1
Q=1, Ii
n <
Iin* -
h
(5)
Whe
r
e,
h
de
fi
n
e
s t
h
e
hy
st
eres
i
s
ban
d
o
f
c
u
r
r
e
nt
co
nt
r
o
l
l
e
r.
If t
h
e l
i
n
e c
u
r
r
e
nt
i
n
c
r
eases
fr
om
uppe
r
hy
st
eresi
s
b
a
nd
,
Q will b
e
zero
to
ind
i
cate th
e cu
rren
t
redu
ction
co
mman
d
.
And
if th
e lin
e cu
rren
t
d
ecreases fro
m
lo
wer
h
y
steresis b
a
nd
,
Q will b
e
one to
sp
ecify the cu
rren
t in
crease co
mm
an
d
.
Before d
e
fin
i
ng
th
e co
n
t
ro
l ru
les, the
m
eaning of voltage regions s
h
ould
be de
fined. In f
act, the input voltage is di
vided to n regi
ons a
n
d each
regi
on
i
s
de
fi
n
e
d as
f
o
l
l
o
wi
n
g
:
R
e
gi
o
n
k:
(
k
-
1
)V
C
< |
V
in
|kV
c
<< ,
0
≤
k
≤
n
(
6
)
Whe
r
e, V
C
i
s
the desi
re
d val
u
e of
DC
capa
c
i
t
o
rs i
n
st
eady
st
at
e and k i
s
a non
ne
gat
i
v
e
i
n
t
e
ger n
u
m
b
er. I
n
Figure 4,
volta
ge regi
ons of i
n
put voltage have bee
n
sh
own. As it can be seen, in
each
region the AC term
inal
v
o
ltag
e
of
rectifier (V
an
),
can
t
a
ke
onl
y
t
w
o
val
u
es
(
k
-
1
)
V
C
or
k
V
C
. F
o
r
speci
fy
i
n
g t
h
e
pr
o
p
er
val
u
e
o
f
V
a
n
,
the s
o
ftwa
re al
gorithm
uses t
h
ese
rules:
a)
If V
in
> 0 and
I
in
> 0 a
nd
Q=
1 t
h
en
V
an
= (k -
1
)V
c
e
l
s
e
i
f
V
in
> 0 a
n
d I
in
>
0
and
Q =
0 t
h
e
n
V
an
=
kV
c
a
n
d z
o
r
bal
a
nci
n
g
DC
bus
es, ca
paci
t
o
rs
wi
t
h
l
o
we
r
vol
t
a
ges a
r
e c
h
o
s
e
n
t
o
be
cha
r
ged
.
b)
If V
in
> 0 a
n
d I
in
< 0 an
d
Q=
1 t
h
en
Va
n= (
k
-
1
)
V
c
else if
V
in
> 0 an
d
I
in
< 0
and
Q =
0 t
h
en
V
an
=
kV
c
a
n
d f
o
r
bal
a
nci
n
g
DC
bus
es, ca
paci
t
o
rs
wi
t
h
l
o
we
r
vol
t
a
ges a
r
e c
h
o
s
e
n
t
o
be
cha
r
ged
.
c)
If V
in
<
0 a
n
d I
in
> 0 a
n
d
Q=1
t
h
en
V
an
= -k
V
c
else if V
in
<
0a
nd
I
in
>
0 a
n
d
Q =
0 t
h
en
V
an
= -(k-
1)
V
c
f
o
r
bal
a
nc
i
ng
DC
b
u
ses,
capaci
t
o
rs
wi
t
h
l
o
we
r
v
o
l
t
a
ges
are c
h
osen
t
o
be c
h
ar
ge
d.
d)
If V
in
< 0 a
nd
I
in
< 0 an
d
Q=1 t
h
en
V
an
= -kV
c
else if V
in
< 0a
nd
Ii
n <
0 a
nd
Q = 0 t
h
en
V
an
=
-
(
k
-
1)
V
c
an
d fo
r balan
c
in
g DC
bu
ses, cap
acitors with lower
vo
ltag
e
s are chosen
t
o
b
e
ch
arged
.
Fi
gu
re
4.
I
d
ent
i
fy
i
ng
v
o
l
t
a
ge
regi
ons
f
o
r
i
n
p
u
t
v
o
l
t
a
ge
Fo
r i
n
stan
ce, in
ru
le on
e when
th
e inpu
t vo
ltag
e
and
inp
u
t
cu
rren
t sig
n
a
ls are
po
sitiv
e and
vol
t
a
ge
re
gi
o
n
i
s
k, t
h
e
val
u
e
of
V
an
will b
e
(k-1)V
C
i
f
Q
=
1 an
d kV
C
if
Q=0
for i
n
cre
a
sing
or
decreasing
th
e inpu
t cu
rren
t as
fo
llowing:
Q=1:
Δ
i+=+(V
in
-
(
k
-1
)V
c
) t
on
/
L
b
Q=1:
Δ
i+= -(kV
c
- V
in
) t
off
/ L
b
(7)
Whe
r
e, L
b
is t
h
e boo
st ind
u
c
to
r
u
s
ed
for shap
ing
th
e inpu
t cu
rren
t.
To
b
e
n
o
ticed
t
h
at this in
du
cto
r
will n
o
t
see v
o
ltag
e
mo
re th
an
± V
c
. In
add
itio
n
i
n
ru
le on
e, for syn
t
h
e
sizing Van
,
tho
s
e cap
acito
rs
with lo
wer
v
o
ltag
e
s are ch
o
s
en
to
b
e
ch
arg
e
d
b
y
p
o
sitiv
e cu
rren
t
, mean
wh
ile th
e to
tal v
o
ltag
e
o
f
capacito
rs
will b
e
regu
lated
b
y
a PI con
t
ro
ller
to
th
e
referen
c
e v
a
lu
e of
n
V
C.If t
h
e
rectifier ap
p
licatio
n
is li
m
i
ted
to
un
ity
p
o
werfactor app
licatio
n
s
, t
h
en th
e ru
les t
w
o
an
d
t
h
ree ar
e omit
ted
an
d
t
h
e
p
o
wer structu
r
e will b
e
su
ch
as o
n
e
sho
w
n i
n
Fi
gu
r
e
2.
Sec
o
nd
st
a
g
e
of
D
P
ET
i
s
t
h
e i
s
ol
at
i
o
n st
age
w
h
i
c
h c
o
nt
ai
ns
n i
s
ol
at
ed
hal
f
b
r
i
d
ge
DC
/
D
C
conve
r
ters c
o
nnected t
o
disti
n
ct DC
link
s
.
In
p
r
im
ary, th
e co
nv
erters ar
e arrange
d
in series connec
tion t
o
p
r
ov
id
e
t
h
e
task
o
f
vo
ltag
e
red
u
c
tion
bu
t
in lo
ad
sid
e
t
h
ey
are se
ries to make c
o
mm
on DC link.
He
re
there
isp
o
ssi
b
ility fo
r wo
rk
ing
su
ch as in
terleav
ed
co
nv
erters
. For ach
iev
i
ng
th
is g
o
a
l, t
h
o
s
e
h
a
lf-bridg
e co
nverters
have e
q
ual dut
y
cycles and the gate signals a
r
e phase s
h
ifte
d equal to T
S
/n
(
T
S
de
fi
nes t
h
e swi
t
c
hi
n
g
per
i
od
of
con
v
e
r
t
e
rs)
.
B
y
appl
y
i
n
g
t
h
i
s
t
echni
que
, t
h
e
out
put
c
u
r
r
ent
ri
p
p
l
e
re
duce
s
co
nsi
d
e
r
abl
y
an
d e
ffi
ci
ency
increases
.
In Figure 5,
t
h
e comm
on
DC link
c
u
rrent (I
L
+i
C
) for two cases (be
f
ore
and afte
r
using the
i
n
t
e
rl
eavi
n
g m
e
t
h
o
d
)
has
bee
n
s
h
o
w
n.
It
ca
n
be see
n
,
by
appl
y
i
n
g
t
h
e
i
n
t
e
rl
eavi
n
g
t
echni
que
, t
h
e
cu
rre
n
t
ri
p
p
l
e
re
duc
es
si
gni
fi
ca
nt
l
y
.
Evaluation Warning : The document was created with Spire.PDF for Python.
I
S
SN
:
2
088
-86
94
I
J
PED
S
Vo
l.
4
,
No
.
4
,
D
ecem
b
er
2
014
:
54
7 – 556
55
2
Fi
nal
l
y
by
c
o
nnect
i
n
g
t
h
e t
h
ree
p
h
ase
v
o
l
t
a
ge so
u
r
ce i
nve
rt
er
t
o
c
o
m
m
on DC
b
u
s
, t
h
e
D
P
ET
st
ruct
u
r
e i
s
co
m
p
l
e
t
e
d. In t
h
i
s
pape
r, t
h
e
v
o
l
t
a
ge sou
r
ce i
n
vert
er i
s
c
ont
r
o
l
l
e
d by
P
W
M
m
e
t
hod.
In t
h
i
s
case,
th
e d
i
rect ax
is, q
u
a
d
r
atic ax
is, an
d
zero
sequen
ce qu
an
tities fo
r three-p
h
ase sin
u
s
o
i
d
a
l sig
n
a
l is co
m
p
u
t
ed
b
y
tran
sform
a
t
i
o
n
.
Th
en
t
h
e
dq
vo
ltag
e
term
s are com
p
ared
by refere
nce si
gnals V
dre
f=
1 a
n
d
V
qref
=
0
and error
si
gnal
s
e
n
t
e
r t
o
P
I
co
nt
r
o
l
l
e
r
s
. The
n
t
h
e PI
out
put
s t
r
ans
f
orm
e
d t
o
t
h
ree
-
p
h
ase si
nus
oi
dal
abc
v
o
l
t
a
g
e
t
e
rm
s
and
are
use
d
t
o
ge
nerat
e
a
p
pr
op
ri
at
e i
n
vert
er
gat
e
pul
ses
.
Fig
u
re
5
.
Co
mm
o
n
DC link
cu
rren
t
b
e
fore an
d after using
t
h
e in
terleav
ing
4.
R
E
SU
LTS AN
D ANA
LY
SIS
4.
1.
Simula
ti
o
n
Result
The co
n
f
i
g
urat
i
on
whi
c
h has
been c
h
osen t
o
co
nfi
r
m
t
h
e
cont
rol
l
e
r
beha
vi
o
r
i
s
a con
v
e
rt
er wi
t
h
5
Half-bridges.
The RMS val
u
e of inpu
t Pha
s
e-Phase voltage is 3.3kV, s
o
the nom
i
nal
peak
voltage of each
p
h
a
se
will b
e
2
694
V.
Th
e referen
ce v
a
lu
e o
f
DC bu
se
s is 60
0V, and
nomin
al p
o
wer of each
Half-b
ri
d
g
e
is
ch
osen
t
o
b
e
6kW, so
th
e nomin
al p
o
wer
of rectifier w
ill b
e
3
0
kW. Th
e
h
y
steresis b
a
nd
o
f
i
n
pu
t
cu
rren
t
and
vol
t
a
ge
ri
p
p
l
e
of ca
paci
t
o
rs
have
been set
t
o
±1 Am
per
e
and ±
4
0 v
o
l
t
,
respect
i
v
el
y
.
Acco
rdi
ng t
o
abo
v
e
assum
p
tions, t
h
e inductor and capac
itors value arecalcula
ted as 4m
H a
nd 60µF. First sim
u
lation shows the
gene
ral
beha
vi
or
o
f
bri
dge
r
ect
i
f
i
e
r w
h
i
l
e
i
t
s
Hal
f
-b
ri
d
g
e
out
put
s
ha
ve
b
een c
o
n
n
ect
e
d
t
o
di
ffe
re
nt
r
e
si
st
or
l
o
ads
(i
n
Fi
gu
r
e
2,
c
onsi
d
er
r
e
si
st
or l
o
ads
i
n
st
ead
of
hal
f
-
b
ri
d
g
e c
o
n
v
e
r
t
e
r
s
).
I
n
Fi
gu
re
6,
t
h
e
Hal
f
-b
ri
d
g
e
DC
bus
es wa
vef
o
r
m
s have bee
n
sho
w
n.
As can
be seen
, i
n
s
p
i
t
e
of
di
ffe
re
nt
l
o
ad
val
u
es
,
DC
bu
ses are
well
app
r
oache
d
t
o
refe
rence
val
u
e
o
f
6
0
0
V
.
T
h
i
s
re
su
l
t
con
f
i
r
m
s
t
h
e ap
pr
op
ri
at
e
vol
t
a
ge
bal
a
nc
i
ng
of
capacitors
.
Fi
gu
re
6.
V
o
l
t
a
ge
wave
f
o
rm
of DC
b
u
ses
In
Fi
g
u
r
e
7,
t
h
e l
i
n
e
cu
rre
n
t
has
bee
n
sh
ow
n.
A
s
ca
n
be see
n
,
t
h
e
i
n
p
u
t
c
u
r
r
e
n
t
a
m
pli
t
ude
ha
s
i
n
crease
d
fr
o
m
10A t
o
2
5
.
2
A
d
u
ri
n
g
l
o
a
d
vari
at
i
o
n
pe
ri
o
d
. T
h
i
s
i
s
l
ogi
cal
beca
use
t
h
e c
ont
rol
l
e
r
sh
oul
d
in
crease th
e i
n
pu
t curren
t
p
r
op
ortio
n
a
l t
o
th
e lo
ad
d
e
man
d
.
For inv
e
stig
ation
abo
u
t
th
e
po
wer facto
r
co
rrectio
n
ab
ility, th
e in
pu
t curren
t
and
inp
u
t
v
o
ltag
e
wav
e
fo
rm
s h
a
v
e
b
e
en
shown
t
o
g
e
t
h
er in
Figu
re
7. It is
obvious
that t
h
e signals a
r
e in phase
(PF=1) and
c
u
rrent shape
is
sinu
so
i
d
al. Also
the THD of i
n
pu
t curren
t
is
12% and it is c
o
m
p
atible with IEEE
519
-1992 standa
rd. T
o
be
noticed that
by inc
r
easing
the loa
d
c
u
rrent, the
in
pu
t curren
t
disto
r
tio
n will
decrease m
o
re.
Evaluation Warning : The document was created with Spire.PDF for Python.
I
J
PED
S
I
S
SN
:
208
8-8
6
9
4
App
lica
tio
n o
f
D
i
strib
u
tion
Po
wer Electron
i
c Tran
sf
o
r
m
e
r
fo
r Med
i
um
Volta
g
e
(Pra
shant Ku
ma
r)
55
3
Fi
gu
re 7(a
)
.
I
n
put
v
o
l
t
a
ge
Fi
gu
re 7(b
)
. I
n
p
u
t
cu
r
r
e
n
t
I
n
Fig
u
re
8
,
t
h
e to
tal A
C
ter
m
i
n
al vo
ltage
o
f
r
e
c
t
i
f
ier (V
an
) an
d
in
d
i
vi
d
u
al
A
C
ter
m
i
n
a
l
v
o
ltage
o
f
h
a
l
f
br
i
d
ges
h
a
ve
b
een s
h
o
w
n, r
e
s
p
ec
tiv
e
l
y
.
Th
is w
a
v
e
f
o
r
m
is o
b
t
aine
d b
y
s
u
m
m
i
n
g
t
h
e i
n
d
i
vi
d
u
al A
C
t
e
r
m
i
n
a
l
o
f
H-
br
i
d
g
e
s.
In
v
e
s
t
i
g
a
t
i
on of
b
o
t
t
o
m
w
a
v
e
f
o
r
m
r
e
v
e
al
s t
h
e
g
ood sw
i
t
c
h
i
n
g
c
h
ar
act
e
r
i
s
t
i
c
s f
o
r
h
a
lf
br
i
d
g
e
s,
b
e
ca
u
s
e t
h
e
nu
m
b
er
o
f
s
w
i
t
c
h
i
ng t
r
a
n
s
i
t
i
on
s i
s
l
o
w
e
r t
h
a
n
30 a
n
d a
g
o
o
d
ef
f
i
ci
e
n
c
y
can
b
e
obt
ai
n
e
d
.
Fi
gu
re
8.
AC
t
e
r
m
i
n
al
v
o
l
t
a
g
e
Fo
r si
m
u
la
tio
n o
f
P
E
T
,
w
e
us
e t
h
e struct
u
r
e s
h
o
w
n
i
n
Fig
u
re
2
.
The b
r
i
d
ge r
e
c
tif
ier is sa
m
e
as t
h
e
o
n
e s
t
ated in pr
evi
o
us s
e
c
t
i
o
n
.
T
h
e p
a
r
a
m
e
t
e
r and c
o
m
p
on
e
n
t valu
e
s
used
in
si
m
u
la
tio
n
have
b
een
l
i
sted
in
ap
p
e
n
d
ix
.1
. In
f
i
rst si
m
u
lat
i
o
n
, th
e P
ET r
e
sp
o
n
se to
v
o
ltage sag
co
n
d
ition
is co
nsid
er
ed
.In
thi
s
ca
se, th
e lo
ad
po
w
e
r i
s
30
k
W
an
d
i
n
p
u
t
v
o
l
t
a
g
e
a
m
p
l
i
t
u
d
e
dec
r
eases
50% b
e
tw
ee
nt
=1
.
2
sa
n
d
t
=
1
.
4
s
.T
h
e
s
i
m
u
l
a
t
i
o
n r
e
s
u
l
t
f
o
r this ca
se h
a
s b
e
e
n
s
h
o
w
n i
n
Fig
u
re
9
.
As it ca
n
b
e
seen, in
s
p
ite o
f
h
e
a
v
y v
o
ltage
d
e
e
p
, th
e l
o
ad
v
o
lta
ge
(p
hase
- neutral vo
lta
ge) isw
e
ll r
e
gu
l
a
ted
and
o
n
l
y
i
n
tra
n
sie
n
t p
o
ints ther
e ar
e s
m
all
a
n
d
sh
o
r
t v
o
ltage
var
i
atio
n
s
.
Figur
e 9.
I
n
p
u
t
v
o
l
t
a
g
e
in S
A
G a
n
d
S
W
ELL
Evaluation Warning : The document was created with Spire.PDF for Python.
I
S
SN
:
2
088
-86
94
I
J
PED
S
Vo
l.
4
,
No
.
4
,
D
ecem
b
er
2
014
:
54
7 – 556
55
4
Secon
d
sim
u
la
tio
n
in
v
e
sti
g
ates th
e PET resp
on
se to
vo
ltag
e
swell co
nd
i
tio
n
t
th
at is in
d
i
actaed
by
b
l
ack
m
a
rk
cicle In
th
is si
m
u
la
tio
n
th
e lo
ad
po
wer is
3
0kW and
inpu
t vo
ltag
e
amp
litu
d
e
in
creases30
%
bet
w
ee
n t
=
1s and t
=
1
.
2s
. Th
e resul
t
fo
r t
h
i
s
case has bee
n
sh
ow
n i
n
Fi
gu
re 9. It
can
be seen des
p
i
t
e t
h
e
v
o
ltag
e
swell; ag
ain
t
h
e l
o
ad
v
o
ltag
e
is
well regu
lated
.
For a
c
h
i
ev
ing
thi
s
goal, the c
o
n
t
r
o
l
l
e
r
i
n
cre
a
ses t
h
e r
e
ference va
l
u
e of
D
C
bu
s
e
s to
V
C
= 6
00V
(
u
p
p
er lim
i
t
). Fig
u
re
1
0
sh
o
w
t
h
at
3
-
p
h
ase o
u
t
p
ut in
f
a
ult co
n
d
itio
ns at
o
u
tp
ut s
i
d
e
.AC o
u
t
p
ut w
i
th
d
e
sired
a
m
p
litu
d
e
a
nd f
r
eq
uenc
y b
y
co
n
n
ec
ti
n
g
d
i
rec
t
l
y
to
DC o
r
A
C
l
o
ad
.
F
i
g
u
r
e
10
.
Three-
ph
ase
ou
tput in
f
a
u
lt cond
itio
n
s
4.
2. C
o
mp
ar
at
i
v
e
A
n
al
ysi
s
Tab
l
e
1
.
Th
e Per
f
o
r
m
a
n
ce Stud
y of
D
F
ET an
d Conv
en
tional Tr
ansfo
r
m
e
r
Meth
od
Definitions
DFE
T
Conventio
nal
f
T
r
ansform
e
r designed
Sem
i
conductor
devices
M
e
tal
Bidirectional power flow capability
Yes
Not possible
No.of
storage capacitors
1
0
Design si
m
p
li
city
and expandability to achieve
higher
r
a
tings
Yes,m
odular
str
u
ctur
e
to any stage
Not possible
Pr
oviding neutr
a
l wir
e
at the input or
output sides
at any
ti
m
e
r
e
quir
e
d
Yes Not
possible
cost ef
f
i
cient, regarding the design si
m
p
li
city, the nu
m
b
er
of DC links capacitor
s
Good
HVDC devices a
r
e
r
e
quir
e
d
Reliability regardi
ng
indepe
ndent operation capability
of phases
Por
t
,
individually
Phases ar
e de-
pendent each other
Pr
oviding desir
e
d voltage and cu
r
r
e
nt and connecting in
se-
ries or connecting
in parallel to
the grid,
s
uitable for
DVR and
AF applications
Yes,
Sa
m
e
devices
No,
Additional
devices r
e
quir
e
d
Independent capability
of providing desired waveform
i
n
each phase , and in
dependent capabili
ty
of
active/re
active power adjust
m
e
n
t
in each phase f
o
r UPQC applications
Yes,
Sa
m
e
devices
No,
Additional
devices r
e
quir
e
d
Transf
er of
active/
reactive power
f
r
om
one phase to an
other
phase or
fr
o
m
one
line to another
line in
power
distr
i
bution sy
stem
act as
I
P
FC
Yes,
Sa
m
e
devices
No,
Additional
devices r
e
quir
e
d
Providing symm
et
rical loads voltage
f
r
o
m
an asy
m
m
e
tri
cal
DC/AC sour
ces for
UPS application
Yes,
Sa
m
e
devices
Not possible
M
a
nagem
e
nt of var
i
able low-
vo
ltage
DC sour
ces suitable for
r
e
newable ener
gy
applications
Yes,
Sa
m
e
devices
Not possible
f
a
ult in Phase
Device work on
other
Phase
Device stop
working
fault clear
ing
online
Not possible
Evaluation Warning : The document was created with Spire.PDF for Python.
I
J
PED
S
I
S
SN
:
208
8-8
6
9
4
App
lica
tio
n o
f
D
i
strib
u
tion
Po
wer Electron
i
c Tran
sf
o
r
m
e
r
fo
r Med
i
um
Volta
g
e
(Pra
shant Ku
ma
r)
55
5
A com
p
ari
s
on st
udy
i
s
gi
ven t
o
cl
ari
f
y
t
h
e
adva
nt
age
o
us
and
di
sad
v
a
n
t
a
geo
u
s
of t
h
e
DPET
.
A
hree
-
pha
se sy
st
em
, cont
ai
n
s
si
x
po
rt
s, i
s
c
o
m
p
are
d
t
o
t
h
e
si
m
i
l
a
r PETs
. Fi
r
s
t
,
s
o
m
e
of t
h
e
p
r
o
s
an
d
con
s
of bi
di
r
ect
i
onal
DPE
T
i
n
com
p
ari
s
on t
o
t
h
e u
n
id
irection
a
l to
po
log
i
es shou
ld
d
i
scu
ss. In
th
e
u
n
i
d
i
rection
a
l
syste
m
s, in
pu
t po
wer
factor
is no
t co
n
t
ro
l
l
a
bl
e
but
i
n
bi
di
rect
i
o
nal
st
r
u
ct
u
r
es i
n
p
u
t
or
ev
e
n
out
put power
factor ca
n be
adjuste
d
. This
m
eans that
the reactive and active power
of eac
h port c
a
n be
regu
lated
.
Also
for DG sy
ste
m
s lik
e win
d
tu
rb
in
e,
b
i
d
i
rection
a
l cap
a
b
ility is in
d
i
sp
en
sab
l
e.
En
erg
y
m
a
nagem
e
nt
for
ene
r
gy
ef
fi
ci
ent
sy
st
em
s i
s
an
ot
he
r a
ppl
i
cat
i
on
of
t
h
i
s
feat
ure
.
A
det
a
i
l
com
p
ari
s
on
st
u
d
y
(e.g
.,
co
st, efficien
cy, qu
ality, etc.) is
g
i
v
e
n in
Tab
l
e
1
to clarify th
e
pro
s
an
d con
s
of DPET.
In additio
n
,
Table 5 s
h
ows
som
e
of the m
o
st noticeable applica
tions
of
DPET
. Dyna
m
i
c voltage restore
r
(DVR) and
active filter (AF) applications can be
satisfie
d
by the FPET, because it can co
nnect to the
grid in se
ries
or/a
nd
in
p
a
rallel. Desired
v
o
ltag
e
an
d
cu
rren
t can
prov
ide by th
e flex
ib
ility o
f
FPET i
n
prov
id
i
n
g
various
wave
f
o
rm
s.
5.
CO
NCL
USI
O
N
Based
o
n
t
h
e requ
irem
en
t o
f
a
po
wer co
nv
ersion
syst
e
m
, PET is propo
sed
t
o
facilitate
man
y
requirem
ents that are e
x
pected in
po
w
e
r
electr
o
n
i
c an
d
d
i
str
i
bu
tio
n syste
m
s. Th
e pro
p
o
s
ed
topo
log
y
is
f
l
ex
ib
le en
ough
to
p
r
ov
id
e
b
i
d
i
r
ection
a
l pow
er
f
l
ow
an
d
h
a
s as m
a
n
y
po
r
t
s as it is r
e
qu
ir
ed
. Fo
r low
-
v
o
ltag
e
appl
i
cat
i
o
n, P
ET can c
o
r
r
e
c
t
po
wer f
a
c
t
or an
d ca
n
adj
u
st
t
h
e
wa
v
e
fo
rm
and fre
que
ncy
o
f
t
h
e
out
put
vol
t
a
ge
. The
p
r
o
p
o
sed t
o
p
o
l
o
gy
can be e
xpa
nde
d f
o
r
hi
g
h
vol
t
a
ge a
n
d hi
gh c
u
r
r
ent
a
p
p
l
i
cat
i
ons. The
dc l
i
n
k
pl
ay
s a
si
g
n
i
f
i
cant
r
o
l
e
t
o
p
r
ovi
de e
n
e
r
gy
bal
a
nce,
po
we
r m
a
nage
m
e
nt
i
n
t
h
e
ci
r
c
ui
t
an
d i
nde
p
e
nde
nt
ope
rat
i
o
n o
f
p
o
r
t
s
. T
h
e PET i
s
ext
r
em
el
y
m
o
dul
a
r
an
d ca
n
be ext
e
nde
d
fo
r di
f
f
ere
n
t
v
o
l
t
a
ge l
e
vel
s
a
n
d
po
we
r
l
e
vel
s
.
It
pe
rf
o
r
m
s
t
y
pi
cal
fun
c
t
i
ons a
n
d
has
adva
nt
age
s
s
u
c
h
as
p
o
w
er
fac
t
or c
o
r
r
ect
i
o
n
and
d
o
ubl
e
gal
v
ani
c
i
s
ol
at
i
on
bet
w
e
e
n eac
h
po
rt
, a
s
wel
l
as
usi
n
g
onl
y
one
st
o
r
a
g
e el
em
ent
.
ACKNOWLE
DGE
M
ENTS
I t
h
a
n
kf
ul
t
o
m
y
wi
fe M
r
s
.
Shi
p
ra
K
u
m
a
ri
f
o
r
he
r
ki
n
d
s
u
pp
ort
an
d
enc
o
ura
g
em
ent
d
u
r
i
n
g t
h
e
pre
p
at
i
o
n
of t
h
e M
a
n
u
scri
pt
.
APPE
NDI
X
A
p
pe
n
d
i
x
1:
D
P
E
T
pa
ra
m
e
te
rs
&
c
o
m
p
o
n
e
nt
v
a
lu
e
s
u
s
e
d
f
o
r
s
i
m
u
l
a
t
i
o
n
REFERE
NC
ES
[1]
E
R
R
ona
n,
SD
Sudh
of
f,
SF
Glov
er
,
D
L
G
a
ll
o
w
ay
.
A p
o
w
e
r
e
l
e
c
t
ron
i
c
-
ba
se
d
d
i
s
t
rib
u
t
i
o
n
t
r
a
n
sformer
.
I
EEE
T
r
an
s.
P
o
we
r D
e
li
v
e
r
y
.
20
02
;
1
7
:
53
7
–
543
.
[2]
P
r
o
o
f
o
f
t
h
e pr
i
n
c
i
pl
e o
f
t
h
e s
o
l
i
d
s
t
ate t
r
ans
f
o
r
m
e
r an
d t
h
e A
C
/
A
C s
w
i
t
c
h m
o
de r
e
g
u
l
a
t
o
r
.
S
a
n Jo
se S
t
ate U
n
i
v
.,
Sa
n
J
ose,
CA
, EP
R
I
T
R
-
1
0
5
06
7,
1
9
95
.
[3]
L
L
i
an
d
D
Che
n
, “
P
h
a
s
e
-
s
hi
f
t
e
d
co
ntr
o
l
l
e
d
f
o
r
w
ar
d
m
o
de A
C
/
A
C
co
nv
e
r
te
r
s
w
ith
hig
h
f
r
e
que
nc
y
A
C
l
i
nks
.
IE
E
E
PE
DS c
o
n
f
.
,
vol.1
,
pp
.
17
2
-
177
,Nov
.
200
3.
[4]
M K
a
ng
,
P
N
E
n
je
t
i
,
I
J
P
i
te
l
.
A
n
a
l
y
s
is
a
n
d
de
s
i
g
n
o
f
e
l
e
c
tr
o
n
i
c
t
r
a
n
s
f
o
r
m
e
r
s
f
o
r
e
l
e
c
tr
ic
po
w
e
r
d
i
s
t
r
i
bu
tio
n
s
y
s
t
e
m
.
P
r
o
c
. I
EEE
I
n
dus
t
r
y A
ppl
i
c
a
t
. S
o
c
.
A
n
n
u
.
Me
e
t
. 19
9
7
.
Pa
ra
m
e
t
e
r
Va
l
u
e
No
.o
finp
utpo
rt
s
5 P
o
r
t
,ser
iesco
nnec
t
ed
No
.o
fo
utputpo
rt
s
3
P
or
t,ser
i
esco
nnec
t
ed
f
t
f
2
k
Hz,
t
rans
f
o
r
m
erfr
eq
uenc
y
L
f1
,
2
,
3
,
4
,
5
4
m
H
(
t
ot
a
l
20m
H
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[5]
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S
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[8]
K
H
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41
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[9]
H K
r
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s
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n
a
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w
a
mi
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R
a
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a
na
ray
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a
n
.
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o
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t
rol
of
hi
gh
freq
u
e
ncy
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elect
r
on
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sformer
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E
E
l
e
c
t
r
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c
P
o
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r
A
ppl
.
2
0
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;
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(3)
:
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–51
6.
[10]
E
R
R
o
n
a
n
,
SD Sudh
of
f,
SF
Glo
v
er
,
DL
G
a
ll
o
w
ay
.
A p
o
w
e
r
el
ec
t
r
on
i
c
-
b
a
s
ed
di
st
ribu
ti
on
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r
an
sf
ormer
. I
EEE T
r
a
n
s.
Pow
e
r D
e
li
v
,
.
2
0
02
;
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7
(2
):
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–5
4
3
.
[11]
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e
r
r
y
,
P
W
h
e
e
le
r
,
J C
l
a
r
e
.
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e
r fl
o
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[12]
M G
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[13]
A
R
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/
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s
.
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T
r
ans
.
P
o
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.
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03;
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8
(
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)
: 1
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–
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.
[14]
Hei
n
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n
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mer
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gh
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s
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la
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ca
pa
bi
li
t
y
.
Proc
eed
i
n
gs
o
f
t
h
e
2002
IEEE
APEC
C
o
n
f
e
r
en
ce
. 20
02;
1: 3
5
2
–
357.
[15]
AJ
Wat
s
o
n
,
PW Wheele
r
, JC
Cl
are.
A co
mplete
har
m
oni
c eli
m
i
n
atio
n a
p
p
r
oac
h
to
DC l
i
n
k
v
o
lta
ge bala
nci
ng
fo
r
a
casca
ded multi
le
vel
rec
tifie
r.
I
EEE
T
r
ans
.
In
d
.
El
ec
t
r
o
n
. 20
07; 54
(6
):
2
9
4
6
–
2
9
53.
[1
6]
V
V
o
r
p
e
r
ian. S
i
m
p
l
i
f
i
e
d
a
n
a
l
ys
is
o
f
P
W
M
c
o
n
v
e
r
t
e
r
s
u
s
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n
g
m
o
de
l o
f
PW
M s
w
itch. Co
nt
in
uo
u
s
co
nd
uc
tio
n
mod
e
.
I
E
EE
T
r
an
s.
Ae
r
o
sp
ac
e E
l
e
c
t
r
on
.
Sys
t
.
199
0
;
26
(
3
)
:
490
–49
6.
BI
O
G
R
A
P
HY
OF
A
U
T
HO
R
Prof.Prashant Kumar graduated
in Electrical
En
gineer
ing from
HETC, West Bengal University
of Technolog
y
,
in 2009 and received M.Tech
in Power Sy
stem from
SR
M University
,
Kattanku
lathur
,
Chennai, Tamiln
adu, Ind
i
a
in 201
3.
He h
a
s 2
y
e
ar
s of industrial ex
perien
ce
and 2
ye
ars
of
ac
adem
ic
experi
enc
e
. H
i
s
are
a
s
of in
ter
e
s
t
are
Optim
iza
t
i
on Te
chniques
,
P
o
wer S
y
s
t
em
S
t
abili
t
y
and R
e
newble
Energ
y
. At pres
ent h
e
is assistant pr
ofessor in the
department of
Electrical Engin
eering
in AMGOI, Kolhapur, Mahars
htra, India.
He Publis
hed Several Pap
e
rs in
Interna
tiona
l/Na
tional J
ourna
ls
as
well as
Inter
n
ation
a
l and Na
tional Conf
eren
ces
P
r
oceedi
ngs
(IEEE
,
Eles
ev
ier
and S
p
ring
er
et
c
.
)
Evaluation Warning : The document was created with Spire.PDF for Python.