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Solar MPPTTechniques
Geno Gargas
ECE 548Prof. Khaligh
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Purpose of Presentation
I. Provide general description of solarMPPT techniques
II. Describe design of solar MPPTMATLAB model constructed
III. Present results of MATLAB simulation
IV. Give analysis of results withrecommendation for future work
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I Basics of MPPT
Solar panel characteristic has non-linear relationship
with Temperature and Irradiance
MPP also moves non-linearly
MPPT can improve efficiency by 15-20%
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Common MPPT methods
Cheap and Easy Implementation
Fractional Open-Circuit Voltage
Fractional Short-Circuit Current
Intermediate Price and Implementation
Perturb and Observe
Incremental Conductance
Expensive and Difficult Implementation
Fuzzy Logic Control
Neural Networks
Increase
dEfficienc
yC
heaperandEasier
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Basic Perturb and Observe
Implemented through a DC/DC converter
Logic
1. Change duty cycle
2. Observeconsequences on
power output
3. Decide direction of
next change in dutycycle
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P & O Design Parameters
Balance d between size of the oscillationacross MPP, and inability to not get confused
Two degrees of freedom: d and Ta
Ta Constraints d
where
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II Creation of MATLAB model
Boost converter with a typical 12V, 64W solarpanel, using the P&O algorithm for MPPT
3 Subsystems
1. Solar Panel
2. Boost
Converter
3. MPPT controller
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1 - PV model design
Vout -
2
Vout +
1
ih
Vpv
v+
-
Rs
Rh
Photocurrent 1
s
-+
Photocurrent
s -
+
Ipv control
Vpv
Ipv
Ih
Temp
Ipv s
Ipv
i+ -
Ih control
Temp
Suns
Ih s
Ih
i+ -
Diode
Suns
2
Temp
1
Important equationsEquivalent
Circuit
MATLAB
Model
I/P -> Sun and
Temperature
O/P -> Panel
voltage
Uses controlled
current sources
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PV model simulation
0 5 10 15 200
0.5
1
1.5
2
2.5
3
3.5
4
4.5
Panel Voltage (V)
PanelCurrent(A)
I-V characteristics for varying irradiance conditions
S = 300 W/m2
S = 500 W/m2
S = 800 W/m2
S = 1000 W/m2
0 5 10 15 200
10
20
30
40
50
60
Panel Voltage (V)
PanelPower(W)
P-V characteristics for varying irradiance conditions
S = 300 W/m2
S = 500 W/m2
S = 800 W/m2
S = 1000 W/m2
I-V and P-V characteristics of simulated PV model
with various levels of irradiance
Very similar to characteristics of real solar panels
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2 Boost converter design
Load
Cin
Vin -2
Vin +
1
triangle
Relational
Operator
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Boost model simulation
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.160
0.5
1
1.5
2
2.5
3
3.5
time (s)
PVcurrent(A)
Panel current at various Duty cycles in Boost converter
D = .1
D = .2
D = .3
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.1612
13
14
15
16
17
18
19
20
time (s)
PVvoltage(V)
Panel voltage at various Duty cycles in Boost converter
D = .1
D = .2
D = .3
Voltage and current of input vs. time for various duty
cycles
Quick transient decay
Low ripple
Input source is model of solar panel
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3 MPPT controller
Timing Sequence
1. Sample new values
after transient
decays
2. Sample for directionof new d
3. Sample values for
use in next period
4. Make change in d
Logic
1. Get Power and Duty values ofK and K+1 periods
2. Figure out direction of
change in duty cycle
3. Change duty cycle
4. Repeat
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Model of controller
Dire
2
Dout
1
direction
In S/H
1
delta D
.1
Memory
OR
AND
NOT
ANDNOT
NOT
NOT AND
OR
AND
D
-1
K
3
P comp
2
D comp
1
Given values from comparing Pk+1 and Pk and Dk+1
and Dk
Performs logic and outputs new duty cycle
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III - Simulation
Test the system during three types of irradiance
1. Fast Changing (50 W/m2s)
2. Slow Changing (15 W/m2s)
3. No Change (0 W/m2s)
Test with different d
1. Large d (d = .02)
2. Small d (d = .005)
0 0.2 0.4 0.6 0.8 1 1.20.89
0.9
0.91
0.92
0.93
0.94
0.95
0.96
time (s)
Irradia
nce(W/m2)
Fast changing irradiance
0 0.2 0.4 0.6 0.8 1 1.20.89
0.9
0.91
0.92
0.93
0.94
0.95
time (s)
Irradiance(W/m2)
Slow changing Irradiance
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Fast Changing Irradiance
0 0.2 0.4 0.6 0.8 1 1.240
42
44
46
48
50
52
54
56
time (s)
Power(W)
Power with D=.02 and fast changing irradiance
0 0.2 0.4 0.6 0.8 1 1.20.3
0.31
0.32
0.33
0.34
0.35
0.36
0.37
0.38
0.39
time (s)
d
utycycle
Duty cycle with D=.02 and fast changing irradiance
(d = .02)
0 0.2 0.4 0.6 0.8 1 1.240
42
44
46
48
50
52
54
56
time (s)
Power(W)
Power with D=.005 and fast changing irradiance
0 0.2 0.4 0.6 0.8 1 1.20.31
0.315
0.32
0.325
0.33
0.335
0.34
0.345
0.35
0.355
0.36
time (s)
dutycycle
Duty cycle with D=.005 and fast c hanging irradiance
(d = .005)
PV
power
Duty
Cycle
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Slow Changing Irradiance
(d = .02) (d = .005)
PV
power
Duty
Cycle
0 0.2 0.4 0.6 0.8 1 1.20.31
0.32
0.33
0.34
0.35
0.36
0.37
0.38
0.39
time (s)
dutycycle
Duty cycle with D=.02 and sl ow changing irradiance
0 0.2 0.4 0.6 0.8 1 1.245
46
47
48
49
50
51
time (s)
Power(W)
Power with D=.005 and sl ow changing irradiance
0 0.2 0.4 0.6 0.8 1 1.20.31
0.315
0.32
0.325
0.33
0.335
0.34
0.345
0.35
0.355
0.36
time (s)
dutycycle
Duty cycl e with D=.005 and slow changing irradiance
0 0.2 0.4 0.6 0.8 1 1.245
46
47
48
49
50
51
time (s)
Power(W)
Power with D=.02 and slow changing irradiance
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No Change in Irradiance
(d = .02) (d = .005)
PV
pow
er
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.545
46
47
48
49
50
51
52
53
time (s)
Power(W)
Power at constant irradiance and D=.02
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5
45
46
47
48
49
50
51
52
53
time (s)
Power(W)
Power at constant irradiance and D=.005
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IV - Results
d Fast change in S Slow change in S No change in S
.02 48.68 W 47.95 W 47.2 W
.005 48.87 W 48.14 W 48.05 W
Average Power in each simulation
These results were found using the mean statistical data providedby MATLAB in each simulation
Average Maximum power available from solar panel
Fast change in S Slow change in S No change in S
Max Power 49.22 W 48.44 W 48.1 W
These results were found by simulating the panel at the average
insolation for each form of change in irradiation, and finding the
maximum point on the power curve.
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Analysis
d Fast change P Slow change P No change P
.02 98.9 % 99 % 98.1%
.005 99.3 % 99.4 % 99.9%
Efficiency of MPPT algorithm for various parameters
Higher efficiency with small d, regardless of how the sun is
changing
I observed that the smaller d takes much longer to get to the
MPP from a step change in irradiance
The step change is a very rare occurrence, so this may not be
an issue
Design the system for the smallest d possible for the best
efficiency
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Future Work
Design a controller that can vary the size of theperturbation with respect to how far from theMPP it is
Leave d at a small value and adjust the
sampling time to see if that has any effect. Simulate the MPPT controller for other
converter types, possibly in line with a batterycharge controller