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2005
1.
[1]-[2].
, 97[%]
5%
,
, 10 ,
,
.
,
(MPPT:
Maximum Power Point Tracking) [3].
,
MPPT ,
.
(
) MPPT
(5 6 / ) ,
.
.
,
. ,
.
IEEE-standard
[4].
UPQC(Unified Power Quality Conditioner)
. ,
.
( 0.9 , THD: 5% ) , MPPT
, (100%)
.
,
Grid-interactive PV Generation system with High Power Quality
*** *** ** * *(Seong-Ryong LeeChil-Hwan JeonSung-Hun KoAh-Ran ChoDae-Up Kang)
Abstract - In this paper, a grid-interactive photovoltaic (PV) system with high power quality is presented, which
gives first priority to maximum power point tracking (MPPT). The proposed system requires only one current
controlled voltage source inverter (CCVSI), which can control the current flow (MPPT operation) at low total
harmonic distortion (THD) and unity power factor, as well as simultaneously provide reactive power support. The
proposed system operation has been divided into two modes (sunny and night). In night mode, the system
operates to compensate the reactive power demanded by nonlinear or variation in loads. in sunny mode, the
system performs power quality control (PQC) to reduce harmonic current and improve power factor as well as
MPPT to supply active power from the PV arrays simultaneously. It is shown that the proposed system improves
the system utilization factor to 100%, which is generally low for PV system (20%). To verify the proposed
system, a comprehensive evaluation with theoretical analysis, simulation and experimental results are presented.
Key Words : , MPPT, Power quality control, CCVSI
* : ** : *** :
2005
.
(PV array) ( )
(CCVSI: Current
Controlled Voltage Source Inverter) ,
.
(PQC: Power Quality Control)
,
MPPT PQC .
CCVSI
.
(24/ )
.
,
.
2.
MPPT
dc/dc
dc/ac two-stage
[5]-[6]. DC
,
[7].
1 dc/ac
single-stage .
1 Single-stage
Fig. 1 Schematic diagram of a single-stage grid-
interactive PV generation system
Load
loadi
CiQ1
Q4
Q2
Q3
PVV
PV array
PVIgi
gV
C1Lc
1 single-stage
.
( )
.
( )
CCVSI
. CCVSI
[8]. CCVSI
.
.
2.1
2 3
.
MPPT PQC
,
PQC .
2
Fig. 2 The equivalent circuit diagram of the proposed
system
LoadGrid CCVSI
0= gGrid VV 0= cCCVSI VV
Ig Ic
Iload
1 CCVSI
2
. CCVSI
.
.gI PVI
cqI
cI
loadpI gV
loadI
gI
cIloadI
gV
(a) (b)
3 Single-stage
Fig. 3 Schematic diagram of a single-stage grid-
interactive PV generation system
2 (Vg ),
(Vc ) (Vload )
, (Iload ) (Ic )
.
(1)
3 (b) (Pload )
2005
. (I*g )
.
(2)
3 (a)
MPPT
.
(I*g ) .
(3)
, Ppv (Vmpp)
.
(MPP)
.
,
dP/dV=0 . MPPT
P&O (Perturbation and Observation)
IncCond (Incremental Conductance)
[9]-[10]. P&O
. IncCond
P&O
MPP
.
(dP/dV)
MPPT
[7].
one-diode (4)
.
(4)
, Ipv Vpv , Iph
, Isat , Rs Rsh
, q , A p-n , K
(Boltzmann`s constant), T
.
(5) (6)
.
(5)
( )
.
(5)
, dP/dV ( I) ( V)
I+( I+ V)V . dP/dV0
dP/dV 0 .
IncCond
.
MPPT
(I*g ) (I*c )
.
(6)
(2) (8)
PQC
, (7)
(Ipvmax ) (3) (8) MPPT
PQC .
2.2
4
Fig. 4 Control block diagram of proposed system
+
loadi
A CD C
P LLS inw t*
gV
V pv
Ipv
Icq*
Icp*
P Q C
M P P T
P R TIc-re f*
V g
Iload
ci pvi
P W M
p vV
G rid
L oad
PVV SIX c
+
Ic
4
MPPT ,
PQC ,
PRT(Polarized RampTime)
.
. ,
,
(2)
(8) sinwt*
2005
(I*cq ) . PRT
(Ic)
PWM . ,
,
MPPT
(Vref) .
dP/dV=I +( I+ V)V dP/dV0
dP/dV 0 .
dc sinwt*
(I*cp )
. PQC
(I*cq )
(I*c-ref ) .
PRT
PWM .
3.
1
[KVA] ,
1 . LS
GMG 01800 14 . GMG 01800
80[W], 17.6 [V], 21.6[V],
4.55[A], 5[A] .
1
Table 1 Conditions and parameters of the experiment
Parameters Values Parameters Values
Vac 220Vrms Vdc 230[70V]
60Hz 5kHz
5mH DC 1000uF
1: 2 1KVA
5
. 5
(a) PQC , (b) PQC
(CH1),
(CH2), (CH3), (CH4) . 5
PQC
.
1:7
. 6 5 FFT
TDS3054B MATH FFT
, THD Voltech PM3000
.
(a)
(b) PQC
5
Fig. 5 Experimental results of proposed system at
night
mode
(a)
(b) PQC
6 FFT
Fig. 6 FFT waveforms of the grid current at nonlinear
load
2005
6 (a) 5 (a) FFT
THD 25.4[%], 0.94 .
6 (b) 5 (b) FFT THD
3.8[%], 0.99 .
0.99
THD 5[%] . 7
9
(CH1), (CH2),
(CH3), (CH4) . 7
(a) MPPT (
) (b) MPPT PQC (
) .
(a)
(b)
7
Fig. 7 Experimental results at inductive load condition
7 (a) MPPT
(0.86 0.51 )
. 9 (b)
MPPT PQC MPPT
(0.99) . 8 5
( ) (a)
470(W/m2 ), (b) 930(W/m2 )
.
8 (a) 470(W/m2 )
. 8 (b) 890(W/m2 )
.
10
.
MPPT
0.99 , THD 5[%] IEEE
.
(a) : 470(W/m2 )
(b) : 890(W/m2 )
8
Fig. 8 Experimental results of proposed system at
sunny
mode
9
,
. 8 (a) 470
(W/m2 )
.
9 MPPT
Fig. 9 Experimental result of proposed system at
decreasing insolation
2005
9
.
4.
MPPT
,
. ,
MPPT
PQC
.
.
1.
0.99 , THD
3.8[%]
IEEE std-1159 .
2. MPPT
.
3. MPPT
PQC
, ,
.
,
. ,
.
97[%]
.
2006
,
.
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