MODELING AND SIMULATION OF POWER
ELECTRONICS DC/DC AND DC/AC CONVERTERS
FOR SINGLE PHASE GRID CONNECTED PV
SYSTEM 220V, 50HZ
Angelina Tomova,
Hristo Anchev,
Anastassia Krusteva
3rd- 4th November 2009, Athens, Greece
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SCOPE AND OBJECTIVES
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The main driving forces that require a change of the energy
production include the depletion of conventional energy
sources, the climate change consideration, the access to
liberalities energy market of European countries.
In this context PV is a key technology. Modeling and
simulation of power electronics part are the objectives related
with optimization of design for diminution the harmonics of
grid connected PV systems.
This presentation focuses on modeling and simulation of power
electronic converters for single phase grid connected PV
system
2 developed by TU Sofia.
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CONTENTS
1.
2.
3.
4.
5.
6.
Introduction
Grid requirements
Synthesis of circuit and PSpice models
Simulation results
Analyses
Conclusion
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INTRODUCTION (1)
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The increasing number of renewable energy sources and
distributed generators requires new strategies for the
operation and management of the electricity grid in order
to maintain and improve the power supply quality and
reliability.
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The power electronics technology plays an important role
in distributed generation for integration of renewable
energy
4 sources into the electrical grid.
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INTRODUCTION (2)
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In 2008, the total installed power generated by Renewable
Energy Sources in Bulgaria is 1648,2 MW. The part of the
installed wind power is 112,6 MW and the photovoltaic power
140 kW but 800 kW is under construction. These projects are
of great interest. Some of installations in Bulgaria are shown on
the next slides.
The generated energy from Renewable Energy Sources in 2008
is 2891,9 GWh including 0,2 GWh generated by photovoltaic
systems and presents 6,5% of the total production of energy in
Bulgaria.
Photovoltaic power plants are mainly connected to the LV
distribution network.
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INTRODUCTION (3)
•PV park in Paunovo
Bulgaria
•1MWp power
•1250MWh per year
•45 hectares surface
•13 365 PV modules thin
layers from Japan
•159 converters from
Germany
•Installed 2009
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INTRODUCTION (4)
•PV park in Srednogortzi
Bulgaria
•7 two axes tracker systems
44,1 kWp
•1,5 hectare surface
•252 PV mono crystalline
modules 175 Wp ”Sharp”
•Connected to LV network
30.06.2008
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INTRODUCTION (5)
•PV plant Yankovo region
Shumen, Bulgaria
•Connected to LV 338 kWp
•North-East 1 project for total
power 2404 kWp
•8 064 PV modules thin layers
Bulgarian production from new
manufacture in Silistra
www.solarpro.bg
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GRID REQUIREMENTS (1)
EN 50160
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Table 1 : Grid requirements EN 50160
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GRID REQUIREMENTS (2)
Figure 1: Individual harmonic values
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Values of individual harmonic
voltages at the supply terminals
for orders up to 2, given in
percent of Un;
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Illustration of a voltage dip and
a short supply interruption
classified according to EN
50160;
Un-nominal voltage of the supply
system (rms)
UA-amplitude of the supply voltage
U(rms)-the actual rms value of the
supply voltage
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Figure 2: Voltage dip
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SYNTHESIS OF CIRCUIT (1)
GRID REQUIRMENTS
PV single phase grid
connected system 5 kWp
z Requirements related to the
grid concerning:
-the voltage- 230V±10%
-the frequency- 50Hz± 1%
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According to the EN 50160 the
requirements concerning the
voltage and the frequency are:
Power
frequency
28 modules SHARP NU180(E1) – each 7 in series,
each 4 x7 in parallel, surface Voltage
1137 m2
total
magnitude
LV, MV: mean value of
fundamental measured over
10s:
± 1% (49.5-50.5) for 99.5% of
week
-6%/+4% (47-52Hz) for 100%
of week
LV,MV: ±10% for 95% of week
mean 10 minutes rms values
variations
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SYNTHESIS OF CIRCUIT (2)
CONCEPT
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The model of the circuit is based on the transformless
concept without energy accumulation which provides high
level of the electric yield- 97% and is used by leading
producers of inverters.
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The PV modules are connected in series as well as in
parallel by the most suitable way in order to obtain the
desired output voltage for the different levels of the global
irradiation.
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SYNTHESIS OF CIRCUIT (3)
RANGE OF THE OUTPUT PARAMETERS
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Depending on the incident
global irradiation the output
parameters at the point of
maximum power (current
and voltage) of the PV
panels are different.
In order to stabilize the
output parameters of the
entire
13 system, we used
DC/DC boost converter.
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Global
Irradiation
[W/m²]
1000W/m²
200W/m²
PMPP [W]
5043
123
UMPP [V]
165,9
154
IMPP [A]
30,4
5,6
Table 2: Range of the output parameters
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SYNTHESIS OF CIRCUIT (4)
BLOCK SCHEME
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The block scheme of the
circuit consists of:
- PV panels
- DC/DC Converter
- DC/AC Converter
- Passive filter
- Command system
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Figure 3 :Block-Scheme
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MODEL OF THE POWER ELECTRONICS
PART- DC/DC CONVERTER (1)
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The diode:
– Type: fast-recovery
– Model: BYT 30P-600/800
– Parameters: URMM=600V,
IFAV=30A
The coil:16 turns on ferrite core
PM 114/93
The transistor
– Type: IGBT;
– Model: IRGPC50S
– Parameters: Uce=600V,
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Ic=41A
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Figure 4: Model of DC/DC Converter
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MODEL OF THE POWER ELECTRONICS
PART- DC/AC CONVERTER (2)
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The transistors:
- Type: NMOS with integrated
diodes
-Model: IRFP 460
-Parameters: UDS=500V,
RDS=0.22Ω, ID=20A
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Figure 5: Model of DC/AC Converter
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SIMULATION RESULTS FOR
THE DC/DC CONVERTER
Figure 6: Simulation results for the
maximum irradiation
Figure 7: Simulation results for the
minimum irradiation
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MODEL OF THE COMMAND SYSTEM
OF DC/AC CONVERTER
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The full bridge inverter control
is made by Unipolar Sinusoidal
Pulse
Width
Modulation
(SPWM)
The traditional method
is
widely used because of the
fewer harmonics introduced
The
traditional
method
compares triangle wave which
is used as carrier with the
sinusoidal
wave
as
the
reference
signal,
whose
frequency is the desired output
frequencyin that case 50Hz
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Figure 8: SPWM- general case
10V
0V
-10V
V(V2:+)
V(V21:+)
V(V16:+)
10V
5V
SEL>>
0V
V(R18:1)
10V
5V
0V
V(U8A:A)
400V
0V
-400V
40ms
42ms
V(M2:s,M4:d)
44ms
46ms
48ms
50ms
52ms
54ms
56ms
58ms
60ms
Time
Figure 9: SPWM- simulation results
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THE COMBINED MODEL OF DC/DC
AND DC/AC
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C1-C8:
electrolytic
capacitors
M1-M4 : NMOS transistors
IRFP840
L2: coil of 203 turns on
ferrite core PM 74/59
C9: capacitor 100µF
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Figure 10 : Combined model
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CHOICE OF THE CAPACITOR LINKING THE
TWO CONVERTERS (1)
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First combined model had the
capacitor
linking the two
converters value of 500μF - the
DC/DC output capacitor and
the DC/AC input capacitor
meanwhile
The output signal of the model
is not the desired sinusoidal
considerable distortions of the
voltage are produced to the
load
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50uV
0V
-50uV
0s
10ms
V(R24:2,L6:2)
20ms
30ms
40ms
50ms
60ms
70ms
80ms
90ms
100ms
Time
Figure 11a: Simulation results for C=500μF
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CHOICE OF THE CAPACITOR LINKING THE
TWO CONVERTERS (2)
12u
10u
8u
6u
4u
2u
0
0 Hz
V( R24 :2, L6 :2)
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0.5 KHz
-I( R24 )
1.0 KHz
1 .5K Hz
2 .0K Hz
2. 5KH z
3. 0KH z
Fr equ enc y
Figure 11b: Fourier analysis for C=500μF
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CHOICE OF THE CAPACITOR LINKING THE
TWO CONVERTERS (3)
100u
40A
0A
50u
SEL>>
-40A
-I(R24)
-I(R24)/SQRT(2)
400V
0
0V
-50u
-400V
0s
10ms
V(R24:2,L6:2)
20ms
-I(R24)
30ms
40ms
50ms
Time
60ms
70ms
80ms
90ms
100ms
0s
10ms
V(R24:2,L6:2)
20ms
30ms
V(R24:2,L6:2)/SQRT(2)
40ms
50ms
60ms
70ms
80ms
90ms
100ms
Time
Fig. 11c - C=1000µF, Voltage
Fig.11d - C=2000µF , Voltage
22 and current results
and current results µF
The results for C=1000μF are not better. For C=2000μF and to C=7000μF the
shapes are appropriate, but the harmonic distortion is considerable
CHOICE OF THE CAPACITOR LINKING THE
TWO CONVERTERS (4)
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The low value of the capacitor can reduce to
considerable distortion of the output voltage
The choice: capacitor value have to increase to
8000 μF
The technical solution: 8 electrolytic capacitors in
parallel, value of each capacitor: 1000 µF
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SIMULATION RESULTS (1)
C=8000 μF
350V
20A
Umax
Icharge
200V
Ieff
10A
Ueff
0V
0A
-10A
-200V
-350V
40ms
V(ch,L6:2)
45ms
50ms
V(ch,L6:2)/ SQRT(2)
55ms
60ms
65ms
70ms
Time
75ms
80ms
-20A
40ms
I(R24)
45ms
I(R24)/ SQRT(2)
50ms
55ms
60ms
65ms
70ms
75ms
80ms
Time
Figure 12: Voltage results
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Umax
= 329 V
URMS=233 V
Figure 13: Current results
Maximum global irradiation
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Imax= 31 A
IRMS=22 A
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SIMULATION RESULTS (2)
C=8000 μF
350V
40A
Umax
200V
20A
Ueff
0V
0A
-200V
-20A
-350V
40ms
45ms
50ms
V(R24:2,L6:2)
V(R24:2,L6:2) * SQRT(2)
55ms
60ms
65ms
70ms
Time
75ms
80ms
-40A
40ms
I(R24)
45ms
I(R24) * SQRT(2)
50ms
55ms
60ms
65ms
70ms
75ms
80ms
Time
Figure 14: Voltage results
Figure 15: Current results
Minimum global irradiation
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Umin
= 327,5 V
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URMS=231,6 V
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Imin= 31 A
IRMS=22 A
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SIMULATION RESULTS (3)
350V
300V
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200V
100V
0V
0Hz
50Hz
100Hz
V(ch,L6:2)
V(ch,L6:2)/ SQRT(2)
150Hz
200Hz
250Hz
300Hz
350Hz
400Hz
450Hz
The Fourier analysis
presents the good concept
of the elements of the
filter and its excellent
performancehigher
harmonics are eliminated
500Hz
Frequency
Figure 16: Harmonic distortion
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SIMULATION RESULTSANALYSES (1)
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The installation will be
connected to the grid in
the two cases:
-Satisfying voltage
-No distortions acting on
the grid quality
-Installed
power
corresponding to the
desired
27 power
Simulations
Maximum
irradiation
Minimum
irradiation
Imax [A]
31
31
IRMS[A]
22
22
Umax [V]
329
327
URMS [V]
233
231,6
P [W]
4870
4840
Table 3: Simulation results
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SIMULATION RESULTSANALYSES (2)
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Excellent operating cycle of the circuit and its model
elaborated in this project
DC/DC converter stabilizes and raises the output voltage
for all irradiation
Sinusoidal shape of the curves of the voltage of the grid
connected 5 kW converter under different irradiation
The received values of the simulations are satisfactory
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CONCLUSIONS (1)
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The progress of the photovoltaic industry should focus on the
development of the photovoltaic technology as well on the problems
concerning the grid connection of PV systems.
The improvement of the power electronic devices is essential. This
part of the system is qualified as the brains of a photovoltaic
installation.
This equipment plays the role of stabilizer of the parameters of the
generated energy and made it suitable for the grid injection.
For the moment some of the grid connected photovoltaic installations
have presented few similar problems regarding the grid: reactive
energy injection to the grid, worsen the grid quality, flicker, and
voltage
29 disturbances.
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CONCLUSION (2)
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The presented investigation may be useful for :
Analyses on generated energy from photovoltaic system
under different global irradiation
Modeling and simulation of power electronic converters
for grid connected PV system
Analyses on the DC/DC power electronic converters
performance to stabilize the voltage level of generated
energy by photovoltaic system
Research on the combined DC/DC and DC/AC scheme its30
performance regarding the aim of grid requirements.
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BIBLIOGRAPHY
1.
2.
3.
4.
Anchev M.Ch, M.S.Minchev, Uninterruptible Power Supply
Systems Sofia, Avangard, 2008- ISBN 978-954-323-419-6 in
Bulgarian
Krusteva A., Tz. Marinov, N.Hinov, Power electronics in distributed
Energy Systems, Electrotechniques & Electronics Journal,Sofia, in
Bulgarian
Anchev M.Ch, Power electronic devices, Sofia, Technical
University 2007, ISBN 978-954-438-695-5, in Bulgarian
Zacharias P., Use of Electronics- Based Power Conversion for
Distributed and Renewable Energy Sources, ISET 2008
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MODELING AND SIMULATION OF POWER ELECTRONICS
DC/DCAND DC/AC CONVERTERS FOR SINGLE PHASE
GRID CONNECTED PV SYSTEM 220V, 50HZ
THANK YOU FOR YOUR ATTENTION!
Eng. M.Sc. Angelina Tomova
e-mail: tomova_angelina@hotmail.com
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