Brief description of solar PV system and study of Maximum Power point tracking techniques. Here two methods has been discussed - 1) Perturbation and observation 2) Incremental conductance.

1. Solar PV system
MPP Tracking techniques
Presented by:
Piyush Agarwal CE16M107
Rakesh Kumar Yadav CE16M109

2. Why Solar power ??
• Limited conventional natural
resource like coal, petroleum &
natural gas
• Greenhouse gas levels are
increasing drastically.
• Global warming and ozone
layer depletion
• Little maintenance required
India, 1954
China, 8206
Germany, 755
United States, 5074
Japan, 1223
Others, 14522
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12000
14000
16000
India China Germany United States Japan Others
CO2 emission in million tons

3. Factors affecting PV generation
• PV cell can convert 12%-19% sunlight energy into electricity
• Dirt and shadow losses is around 8%
• Module losses around 50%
• System losses (cables and inverter) of around 5 %
• Module losses around 50%
• Overall efficiency is around 16%

4. Modeling of photovoltaic cell
The power output can be calculated as P=V*I.
Voltage at the maximum power point can be
calculated as

5. PV cell characteristics

6. Block Diagram of a typical
photovoltaic system

7. Boost converter
When a direct connection is carried out
between the source and the load, the output of
the PV module is irregularly shifted away from
the maximum power point. It is necessary to
overcome this problem, so we have added one
adaptation circuit between the source and the
load. And a MPPT controller circuit with a DC-
DC converter circuit is used as an adaptive
circuit.

8. Functions
• Blocking Diodes-facilitates the array generated power to flow only
towards the power conditioner
• the charge -discharge controller is responsible for
preventing overcharging or over discharging of the battery bank
• battery bank is required to store electricity generated by the solar
energy to use during sunless time.
• MPPT is used to maximize the power output.
• Inverter is used to convert dc power to ac power to be supplied in the
grid and for local loads.

9. MPPT
• An algorithm used for extracting maximum available power from PV
module under certain conditions.
• Voltage at which PV module can produce maximum power is called
'maximum power point‘.
• MPP changes with temperature and intensity of light, so tracking is
required.
• MPPT gives triggering signal to the DC-DC boost controller .

10. Perturbation & Observation Algorithm
• the module voltage is periodically
given a perturbation and the
corresponding output power is
compared with that at the
previous perturbing cycle.
• With the perturbation, power can
either be increased or decreased.
• Simplest method of power
tracking
• Sampled voltage and current
value is used to calculate power.

12. P&O Disadvantages
1. During rapidly changing irradiation, it is possible for the
classic P & O algorithm to get confused and track the MPP in
the wrong direction
2. At steady state, the operating point oscillates around the MPP voltage
giving rise to the waste of some amount of available energy.
3. Poor efficiency at low irradiation.
4. Small step size increase efficiency but reduces speed.
5. Perturbation size must be sufficient to prevent system to be affected by
measurement noise

13. P&O Disadvantages
1. Changing irradiation
Starting from an operating point A, if atmospheric
conditions stay approximately constant,
If the irradiance increases and shifts the power curve
from P1 to P2 within one sampling period, the operating
point will move from A to C.

14. P&O Disadvantages
2. Oscillations about MPP
Oscillation-
Case 1

15. P&O Disadvantages
2. Oscillations about MPP
Case 2

16. Improved P&O
• Variable step size should be implemented to increase efficiency and speed simultaneously.
• When the system starts up and environment varies, constant step size is used to firstly to make
the working point close to the MPP stably, then oscillations near MPP and misjudgements
during environmental varies would be solved by variable step P&O method.
• The principle of constant voltage method is based on the near linear relationship Vm = K*Voc
where K is between 0.71-0.78, determined by PV system parameters.
• The smaller dp/dv is , the nearer working point is to the MPP.
• If dp/dv < 0, the operating point is to the right of MPP and vice versa.
• The steps are not equal on the left and right sides of MPP where their powers are equal, the left
step is larger than the right.
• b and a (b>a) are step proportionality coefficients on left and right sides of MPP

17. Improved P&O

18. Simulation result
1000 w/m2
1200 w/m2
1200 w/m2
1000 w/m2
Fixed Step
Variable Step
Inferences-
• Startup time reduces
• improve the speed of system response
when the irradiance changes suddenly

19. Incremental Conductance Method
Searches for the voltage
operating point at which the
conductance is equal to the
incremental conductance .
Once MPPT is reached, it stops
oscillating

20. Improved InCnd
• The direction of perturbation embedded in the
variable step-size Vstep itself, therefore the flowchart
of the variable step-size INC algorithm is more
concise than the fixed step-size one.
• The acceleration factor β , should be a small positive
number near to zero.
• A change in ∆𝐼 indicates a change in atmospheric
conditions.
•

21. Inferences
• Automatically adjusts the step
size according to the
operating point of the PV
array.
• When the operating point is
far from the MPP of the PV
array, the step size is great
and the operating point of the
PV array approaches quickly
to the MPP and vice versa.
Improved InCnd

22. Comparison
P & O Incremental Conductance
Cannot track MPP in fast varying
environmental conditions
It can track MPP in fast varying
environmental conditions.
Oscillates about the MPP which
results in power loss.
Once it has reached the MPP and it
stops perturbing the operating point.
Simple to implement Increased hardware and software
complexity
Less computation is required and
hence is fast
Increased computation times which
slows down sampling rate

23. References
• Comparison of Photovoltaic Array Maximum Power Point TrackingTechniquesTrishan Esram; Patrick L.
Chapman IEEE Transactions on Energy ConversionYear: 2007, Volume: 22, Issue: 2
• A variable step-size P&O method in the application of MPPT control for a PV system XuYang
Zhang; HuaGuang Zhang; HanQing Zhang; PengQiao Zhang; Feng Wang; Hong Jia; DeYu Song 2016 IEEE
Advanced Information Management, Communicates, Electronic and Automation Control Conference
(IMCEC)Year: 2016
• Analysis and Improvement of Maximum Power Point Tracking AlgorithmBased on Incremental Conductanc
e Method for Photovoltaic Array Bangyin Liu; Shanxu Duan; Fei Liu; Pengwei Xu 2007 7th International
Conference on Power Electronics and Drive SystemsYear: 2007

24. Thank you
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