The document discusses maximum power point tracking (MPPT) techniques for photovoltaic systems. It describes: 1) MPPT is used to maximize the power extracted from solar panels by adjusting the operating voltage to match the maximum power point. This can increase efficiency by 20-30%. 2) The main MPPT techniques are offline (open-circuit voltage, short-circuit current), online (perturb and observe, incremental conductance), and intelligent (artificial neural networks, fuzzy logic). 3) Each technique has advantages - offline is simple but less accurate, online tracks changes better but with more complexity, and intelligent methods are very robust but complex to implement. The best choice depends on the application

1. MAXIMUM POWER POINT TRACKING
SYSTEM FOR PHOTO VOLTAIC
SYSTEMS
Presented by Guide
P.PRIYADARSINI M.MURALI KRISHNA,M.Tech
19MT8405

2. Contents...
 OBJECTIVE
 MATHEMATICAL MODEL
 WHAT IS MPPT?
 SYSTEM MODELLING
 MPPT TECHNIQUES
 APPLICATIONS
 CONCLUSION

3. OBJECTIVE
 Solar Cell
A solar cell,or photo voltaic cell,is an electrical device that converts the energy of
light directly into electricity by the photo voltaic effect.
 Efficiency of solar cell is less,it only converts 30-40% of energy incident on it to
electrical energy.
 Need to use solar energy
Pollution free
Maintenance free
Silent operation
Long life time
 Efficiency of solar cell increased by this technique called MPPT,by installing this
technique we can get additional 20-30% of efficiency.

4. Mathematical model of solar cell
Equivalent circuit of PV cell
Current equation
I=IL-ID-Ish
I -Cell current(A)
IL -light generated current(A)
Io -Diode saturation current
q -Charge of electron
=1.6*10^-19(coul)
K -Boltzman constant(j/K)
T -Cell temperature(K)
Rs,Rsh are cell series and shunt
resistance(ohms)
V -Cell output voltage(V)

5. V-I and P-V Characteristics of a solar cell

6. Variation of I-V and P-V curves with solar irradiation

7. Variation of I-V curve with temperature

8. Variation of P-V curve with temperature

9. Maximum Power Point Tracking(MPPT)
 MPPT
Maximum power point tracking or sometimes power point tracking is a
technique used commonly with wind turbines and PV systems to
maximize power extracting under all conditions.
Generally MPPT is installed in between PV system&load. Coupling to the
load for maximum power transfer may required either providing a higher
voltage at lower current or lower voltage at higher current.
 Maximum power point(MPP)
It is an operating point at which maximum power can be extracted from
the system,usually represents maximum power point(MPP).

10. System modelling

11. Classification Of MPPT Techniques
Offline
Technique
• Open Circuit Voltage
• Short Circuit Current
Online
Technique
• Perturb&Observe
• Incremental Conductance
Intelligent
Technique
• Artificial Neural Network
• Fuzzy Logic Control

12. Offline Technique
 The offline technique is commonly called as indirect technique since this algorithm
is worked in offline i.e. not on the real time.
 In this technique, there is a necessity of prior requirement of particular PV panel
data such as the mathematical modeling, I-V, P-V curve, etc.
 The basic indirect techniques of MPPT are open circuit voltage and Short circuit
current method.
 In both the methods, a DC/DC converter with the driver circuit is controlled by the
micro controller or DSP operates either in Buck/Boost mode is required.
 The duty cycle of the switching converter can be varied based on the computation
of the open circuit voltage or short circuit current to track the maximum power
point (MPP).

13. Open circuit voltage
 In this technique, the value of Vmpp under
different solar insolation and temperature is
calculated approximately by the equation:
Where
Voc -is the open circuit voltage
K1 -is the coefficient value
ranges from 0.71 to 0.9 depending upon the
characteristics of the panel.
 The value of Vmpp is computed by
measuring the value of Voc periodically.
Short circuit current
 In this technique,The peak value of current Impp
is computed by the following equation as:
Where
K2 -is the coefficient value ranges from 0.73 to
0.95 depending on the cell material and
characteristics of the PV panel.
 By computing the values of Impp, at different
sampled values of Isc, the duty cycle of the
DC/DC converter is increased or decreased so
that the output current becomes equal to Impp.
Vmpp=K1Voc
Impp=K2Isc
Offline Techniques

14. Online Technique
 The online technique is commonly called as direct technique since
this algorithm is worked in real time i.e. not on the offline.
 The popular online techniques used directly for the maximum
power point are Perturb and Observe Technique (P&O) and
Incremental conductance Technique (INC).
 In the direct techniques, there will be an online measurement of
voltage and measurement of the panel periodically for computing
the duty cycle of the converter to track the maximum power point
MPPT.

15. Perturb&Observe MPPT Technique
 In this different MPP for different condition of temperature and irradiation which is
tracked by MPPT technique and can be delivered to load.
 The P&O MPPT technique algorithm calculates the power P(t) by measuring the
instant voltage V(t) and current I(t) and then compares it with last calculated power
P(t-1).
 The algorithm continuously perturbs the system if the operating point variation is
positive; otherwise the direction of perturbation is changed if the operating point
variation is positive.
 The duty cycle of the DC/DC converter is varied till it reaches the maximum power
point.
 With higher step size of perturbation, system may oscillate around MPP which
results into wastage of energy.

16. P&O MPPT
Technique
Flowchart
Yes
No
strart
Measure V(t),I(t)
P(t)=V(t)*I(t)
▲ P=P(t)-P(t-1)
▲P>0
▲V>0
▲V>0
Decrease
voltage
Increase
voltage
Return
Increase
voltage
Decrease
voltage

17. Incremental Conductance Technique
 This is a most popular MPPT algorithm and widely used.
 The disadvantages of the P&O MPPT algorithm is overcome and eliminated by this INC
technique but it is more complex and very difficult to implement.
 The theory of the incremental conductance is to determine the variation direction of the
output terminal voltage of the PV modules by measuring and comparing the incremental
conductance and instantaneous conductance of PV modules.
 If the value of incremental conductance and the instantaneous conductance are equal,
then it represents the operating point reaches the MPP maximum power point.
 Compare to the offline techniques, the online techniques like incremental conductance
(INC) algorithms are advantageous under rapidly changing atmospheric conditions but it
involves complex calculation which increases the hardware requirement and cost.

18. INC MPPT Technique Flowchart
dP/dV=0 at MPP
dP/dV>0 left of MPP
dP/dV<0 right of MPP
dP/dV = d(VI)/d(V)= I + V*dI/dV
The dP/dV is defined as Maximum power point identifier factor.By
utilizing this factor, the INC method is proposed to effectively track the
MPP of PV module.

19. Intelligent Technique
 Intelligent MPPT controllers are very robust than
conventional nonlinear controllers and it is able to
effectively improve the dynamic response and
steady state performance of the PV systems.
 The popular intelligent techniques are
Artificial Neural Network
Fuzzy Logic Control

20. Artificial Neural Network
 It is a new emerging technology used to solve complex problem. It
is best suited for approximation of non-linear system.
 Input, hidden and output are the three layers of the artificial neural
network.
 Feed forward type of neural network is the simplest one and it
passes the information only in forward direction to all the layers.
 the numbers of nodes are defined by the user and varied based
on the requirement.

21. Block Diagram of ANN
 Input of the neural network for
maximum power point tracking
PV array parameters such as
PV voltage and current,
environmental data like
irradiance and temperature, or
the combination of these.
 the output layer may be in the
form of voltage, duty cycle
depending.
Input
Layer
Hidden
Layer
Output
Layer
Tr
Vmpp
Ir
IPV
PPV

22. Fuzzy Logic Control
 For over a decade Fuzzy Logic MPPT is popular and most powerful control method.
It works with estimated inputs, ability to handle non-linearity, and have no need of
accurate mathematical model; these are the advantages of the fuzzy logic control.
FLC consist three state; fuzzification, decision-making and defuzzification.
 The inputs of the FLC are usually an error E and change error ▲E. To track
maximum power point error is computed based on irradiance and temperature or
instantaneous values such as power and voltage. The output signal is either the duty
cycle itself, or & from which the duty cycle can be generated
Fuzzification
Decision-making
Base
Defuzzification
E
▲E

23.  Fuzzification: The process of converting numerical value into
linguistic variable. The interval [-1 1] of membership function are
chosen for the inputs. As in PV array for MPPT voltage and power are
the two variables used to describing the control rule.
 Decision making base rule: In this base rule, the system behavior of the
input/output variable are derived from the IF – THEN rule. To satisfy
different condition rule base tables are obtained which gives several
possible combinations of the degree which varying strengths to the
corresponding rules.
 Defuzzification: The numerical variable outputs are obtained by
converting linguistic variable. To control the power and derive the
operating point to the MPP, analog signals are provided.

24. Applications
 The high end application like space satellites and Orbital stations, the complexity of
the algorithm, costs doesn’t matter, the only requirement is to track the true MPP
within a stipulated time period and no need of periodic tuning. In this type of special
applications, P&O and INC are more appropriate.
 In the case of large scale PV power plants, the efficiency of the MPPT method
constitutes the most important initial consideration and the hybrid MPPT algorithm
one is the best option. In the case of designing the solar vehicles would mostly
require the convergence speed to the MPP to be very fast. Fuzzy Logic, Artificial
neural network MPPT will be preferred for high speed of convergence to the MPP.
 Open circuit voltage and Short circuit current algorithms will be sufficient for the PV
systems used for street lightning since it does not require any more tight constraints
and only easy and cheap implementation is required.

25. Conclusion
 This presentation reviews the various MPPT algorithm techniques
that have been used for Photo voltaic system at changes in
irradiance and temperature. The selection of a particular MPPT
technique is based on type of application.
 It can be concluded that the offline and online techniques are working
very well only when the solar irradiation is uniform. But it failed to
approach the true MPP when it comes under rapidly changing
atmospheric and partial shaded conditions. This drawback was
overcome by the new MPPT techniques.