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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 constructedIII. 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 methodsCheap and Easy Implementation
Fractional Open-Circuit Voltage
Fractional Short-Circuit Current
Intermediate Price and ImplementationPerturb and Observe
Incremental Conductance
Expensive and Difficult ImplementationFuzzy Logic Control
Neural Networks
I n
c r
e a s e d
E f f i c i en
c
y C h e a p e r a n
d E a s
i e r
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Basic Perturb and ObserveImplemented through a DC/DC converter
Logic
1. Change duty cycle
2. Observeconsequences onpower 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 confusedTwo degrees of freedom: d and Ta
Ta Constraints d
where
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II Creation of MATLAB modelBoost converter with a typical 12V, 64W solarpanel, using the P&O algorithm for MPPT
3 Subsystems1. Solar Panel
2. BoostConverter
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
Suns2
Temp1
Important equationsEquivalentCircuit
MATLABModel
I/P -> Sun andTemperature
O/P -> Panelvoltage
Uses controlledcurrent 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)
P a n e l
C u r r e n t
( A )
I-V characteristics for varying irradiance conditions
S = 300 W/m 2
S = 500 W/m 2
S = 800 W/m 2
S = 1000 W/m 2
0 5 10 15 200
10
20
30
40
50
60
Panel Voltage (V)
P a n e l
P o w e r
( W )
P-V characteristics for varying irradiance conditions
S = 300 W/m 2
S = 500 W/m 2
S = 800 W/m 2
S = 1000 W/m 2
I-V and P-V characteristics of simulated PV modelwith 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
RelationalOperator
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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)
P V c u r r e n
t ( 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)
P V v o
l t a g e
( 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 dutycycles Quick transient decay
Low ripple
Input source is model of solar panel
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3 MPPT controller
Timing Sequence1. Sample new values
after transientdecays
2. Sample for directionof new d
3. Sample values foruse in next period
4. Make change in d
Logic
1. Get Power and Duty values ofK and K+1 periods
2. Figure out direction ofchange in duty cycle
3. Change duty cycle
4. Repeat
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Model of controller
Dire2
Dout
1
direction
In S/H
1
delta D
.1
Memory
OR
ANDNOT
ANDNOT
NOT
NOT AND
OR
AND
D
-1
K3
P comp
2
D comp1
Given values from comparing P k+1 and P k and D k+1 and D k
Performs logic and outputs new duty cycle
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III - Simulation
Test the system during three types of irradiance1. Fast Changing (50 W/m 2s)
2. Slow Changing (15 W/m 2s)
3. No Change (0 W/m 2s)
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)
I r r a d i a n c e
( W / m
2 )
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)
I r r a d
i a n c e
( W / m
2 )
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)
P o w e r
( 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 u t y c y c l e
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)
P o w e r
( 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)
d u t y c y c l e
Duty cycle with D=.005 and fast c hanging irradiance
(d = .005)
P V p o w e r
D u t y
C y c
l e
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Slow Changing Irradiance
(d = .02) (d = .005)
P V p o w e r
D u t y
C y c
l e
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)
d u t y c y c l e
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)
P o w e r
( 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)
d u t y c y c
l e
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)
P o w e r
( W )
Power with D=.02 and slow changing irradiance
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No Change in Irradiance
(d = .02) (d = .005)
P V p o w e r
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)
P o w e r
( 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 0.545
46
47
48
49
50
51
52
53
time (s)
P o w e r
( 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 averageinsolation 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 ischanging
I observed that the smaller d takes much longer to get to theMPP from a step change in irradiance
The step change is a very rare occurrence, so this may not bean issue
Design the system for the smallest d possible for the bestefficiency
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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 thesampling time to see if that has any effect.Simulate the MPPT controller for otherconverter types, possibly in line with a batterycharge controller