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Automatic Peak Power Automatic Peak Power Tracker using dSPACETracker using dSPACERR

M.Tech Thesis Presentation M.Tech Thesis Presentation

ByBy

Vikrant A.Chaudhari.Vikrant A.Chaudhari.

Under the guidance of Under the guidance of

Dr.S.Rangnekar.Dr.S.Rangnekar.

Renewable EnergyRenewable Energy

Alternate sources of energyAlternate sources of energy

1.1. Biomass.Biomass.

2.2. Solar Energy.Solar Energy.

3.3. Wind Emergy.Wind Emergy.

4.4. Geothermal Energy.Geothermal Energy.

5.5. Microhydel.Microhydel.

6.6. Fuel cells.Fuel cells.

Why Solar Energy.Why Solar Energy.

Solar energy is the most readily Solar energy is the most readily available source of energy. available source of energy.

It is free. It is free. It is also the most important of the It is also the most important of the

non-conventional sources of energy non-conventional sources of energy because it is non-polluting. because it is non-polluting.

Facts about solar energy.Facts about solar energy.

Earth surface receives 1.2x10Earth surface receives 1.2x101717 W of W of power from sun.power from sun.

Energy supplied by the sun in one Energy supplied by the sun in one hour is almost equal to the amount hour is almost equal to the amount energy required by the human energy required by the human population in one year.population in one year.

Most if the other source on Most if the other source on renewable energy have their in sun.renewable energy have their in sun.

How electricity is generated How electricity is generated through Solar Energythrough Solar Energy

Solar photo voltaic (SPV). Can be Solar photo voltaic (SPV). Can be used to generate electricity form the used to generate electricity form the sun.sun.

Silicon solar cells play an important Silicon solar cells play an important role in generation of electricity.role in generation of electricity.

Solar cells Solar cells Characteristics.Characteristics.

Isc-short circuit Isc-short circuit current.current.

Voc-open circuit Voc-open circuit voltage.voltage.

Peak power.Peak power.Isc

Voc

How solar cells Generate How solar cells Generate electricityelectricity

From Cells to ModulesFrom Cells to Modules The open circuit voltage of a single The open circuit voltage of a single

solar solar cell is approx 0.5V.solar solar cell is approx 0.5V. Much higher voltage voltage is Much higher voltage voltage is

required for practical application.required for practical application. Solar cells are connected in series to Solar cells are connected in series to

increase its open circuit voltage.increase its open circuit voltage.

Characteristics of a typical Characteristics of a typical Solar Pv Module.Solar Pv Module.

VariationVariation of of characteristics of characteristics of Solar module with change in Solar module with change in the atmospheric conditionsthe atmospheric conditions

Variation due to isolation ChangeVariation due to isolation Change

VariationVariation of of characteristics of characteristics of Solar module with change in Solar module with change in the atmospheric conditionsthe atmospheric conditions

Variation due to Temperature change.Variation due to Temperature change.

Conclusion from the Conclusion from the Characteristics.Characteristics.

Power of the module has only single Power of the module has only single maxima.maxima.

Peak Power of the module changes Peak Power of the module changes with the change in temperature.with the change in temperature.

Peak power of the module changes Peak power of the module changes with the change in isolation level.with the change in isolation level.

Need to track the peak power in Need to track the peak power in order to maximize the utilizations of order to maximize the utilizations of the solar module/array.the solar module/array.

How Peak Power is tracked.How Peak Power is tracked.

Peak Power is tracked by adjusting Peak Power is tracked by adjusting the impedance of the load.the impedance of the load.

This is obtained by using an This is obtained by using an interface between the load and the interface between the load and the solar module.solar module.

A Dc/Dc converter can act as a A Dc/Dc converter can act as a interface between the load and the interface between the load and the module.module.

Block DiagramBlock Diagram

How Peak Power is tracked.How Peak Power is tracked.

Conclusion.Conclusion.

Dc/Dc converter is must in tracking Dc/Dc converter is must in tracking peak power.peak power.

Duty cycle of the converter needs to Duty cycle of the converter needs to be changed for adjusting the peak be changed for adjusting the peak power.power.

How to adjust the duty cycle?How to adjust the duty cycle? Manual or Automatic.?Manual or Automatic.?

DC/DC convertersDC/DC converters

Vi

Vo=D*Vi

D=duty cycle=Ton/T

Step Down Converter

RL

Pulse

L

1

g

2

m

Ideal Switch

G4G3

G2 G1

DC Voltage

a

k m

D

C

Step down converter Vo=D*ViStep down converter Vo=D*ViVo<ViVo<Vi

DC/DC convertersDC/DC converters

Vi

Vo=Vi/(1-D)

D=duty cycle=Ton/T

Step Up Converter

RL

Pulse

L

1 g

2 m

Ideal Switch

G4G3

G2 G1

DC Voltage

ak

m

D

C

Step up Converter Vo=Vi/(1-D)Step up Converter Vo=Vi/(1-D)Vo>ViVo>Vi

Duty CycleDuty Cycle

D=tD=tonon/t/t

Methods of obtaining Methods of obtaining Peak PowerPeak Power

Though Manual tracking is Though Manual tracking is possible but is waste of time.possible but is waste of time.

Automatic tracking is a better Automatic tracking is a better choice.choice.

Algorithms are used for Algorithms are used for Automatic Peak Power tracking.Automatic Peak Power tracking.

Different Algorithms.Different Algorithms.

Perturb & Observe. (P&O).Perturb & Observe. (P&O). Incremental conductance.Incremental conductance. Parasitic Capacitance method.Parasitic Capacitance method. Voltage Based Peak Power Voltage Based Peak Power

Tracking.Tracking. Current Based Peak Power Current Based Peak Power

Tracking.Tracking.

Perturb & Observe Perturb & Observe

Incremental Incremental Conductance Conductance

Parasitic Capacitance Parasitic Capacitance Account the parasitic capacitances ofAccount the parasitic capacitances of The solar cells in the PV array The solar cells in the PV array . . Parasitic Parasitic

capacitance uses the switching ripple of thecapacitance uses the switching ripple of the PPT to perturb the array. PPT to perturb the array. To account for the parasitic capacitance, To account for the parasitic capacitance,

the average ripple in the array power and the average ripple in the array power and voltage, generated by the switching voltage, generated by the switching frequency, are measured.frequency, are measured.

The incremental conductance algorithm is The incremental conductance algorithm is then used to determine the direction to then used to determine the direction to move the operating point of the MPPT. move the operating point of the MPPT.

Voltage Based Peak power Voltage Based Peak power Tracker.Tracker.

Peak Power point of the module is at Peak Power point of the module is at 76% of the module open circuit voltage.76% of the module open circuit voltage.

This value is fixed and does not vary This value is fixed and does not vary much with the changes in the much with the changes in the environmental conditions.environmental conditions.

By measuring the open circuit voltage By measuring the open circuit voltage and adjusting the module voltage to and adjusting the module voltage to about 76% of Voc the peak power can about 76% of Voc the peak power can be tracked.be tracked.

Current Based Peak Power Current Based Peak Power Tracker.Tracker.

Peak Power of the module lies at Peak Power of the module lies at about 95% of its short circuit about 95% of its short circuit current.current.

Measuring the short circuit current Measuring the short circuit current Isc and adjusting the operating the Isc and adjusting the operating the converter at 95% of Isc the module converter at 95% of Isc the module can be made to operate at Peak can be made to operate at Peak power.power.

Algorithm Used in the Algorithm Used in the Present Report.Present Report.

AlgorithmAlgorithm Module Voltage and Current Module Voltage and Current

measured at kmeasured at kthth instant. instant. Power is calculated at kPower is calculated at kthth instant. P(k) instant. P(k) P(k) stored in the memory.P(k) stored in the memory. Module Voltage and current Module Voltage and current

calculated at k+1calculated at k+1thth instant. instant. Power at k+1Power at k+1thth.. ∆∆P=P(k+1)-P(k).P=P(k+1)-P(k).

AlgorithmAlgorithm Also ∆V=V(k+1)-V(k).Also ∆V=V(k+1)-V(k). Depending on the sign of the ∆P and ∆V Depending on the sign of the ∆P and ∆V

the duty cycle of the module is varied.the duty cycle of the module is varied. If ∆P>0 and ∆V>0 then D=D- ∆D.If ∆P>0 and ∆V>0 then D=D- ∆D. If ∆P>0 and ∆V<0 then D=D+ ∆D.If ∆P>0 and ∆V<0 then D=D+ ∆D. If ∆P<0 and ∆V <0 then D=D+ ∆D.If ∆P<0 and ∆V <0 then D=D+ ∆D. If ∆P<0 and ∆ V>0 then D=D- ∆D.If ∆P<0 and ∆ V>0 then D=D- ∆D. Were D= duty cycle and ∆D is Were D= duty cycle and ∆D is

perturbation.perturbation.

Simulation of the Peak Simulation of the Peak Power trackerPower tracker

Simulation in Matlab/Simulink.Simulation in Matlab/Simulink. Model of solar PV module developed.Model of solar PV module developed. Model of Dc/Dc converter.Model of Dc/Dc converter. Load.Load. Development of PPT algorithm in Development of PPT algorithm in

Simulink.Simulink.

Solar PV Module Model.Solar PV Module Model.

Id

ILIph

V

> >

RL

Rs

IphD

Electrical Model of PV CellElectrical Model of PV Cell

Model of PV Module.Model of PV Module.1

+

-K-

temp coeficent Voc

-K-

temp coeficent Isc

25 room Temp constant

an

od

ec

ath

od

e

diodes

-K-

amps/W/m^2

+- v

Voltage 1

Product

L

signal

Iph

G4 G3

G2

G1

15.32

Display2

signal

+

-

Controlled Source

Rs

3 -

2

ambient temp

1

insolation

Simulink Model of Solar PV Module.Simulink Model of Solar PV Module.

Model of Solar PV Model of Solar PV Module.Module.

Simulink Model of the Simulink Model of the PPTPPT

Simulink Model of the Simulink Model of the AlgorithmAlgorithm

Peak Power Tracking.Peak Power Tracking.

dSPACEdSPACERR

A real time Control solution.A real time Control solution. Control of hardware through Control of hardware through

Personal computer.Personal computer. Works on Matlab/Simulink Platform.Works on Matlab/Simulink Platform. Automatic C code generation.Automatic C code generation. Easy to generate control logic in Easy to generate control logic in

Matlab/Simulink and downloading to Matlab/Simulink and downloading to the dSPACE add on card.the dSPACE add on card.

Experimental SetupExperimental Setup

Solar module Solar module Dc/Dc converter(step up and Dc/Dc converter(step up and

step down).step down). A load (resistive load)A load (resistive load) Personal computerPersonal computer

(installed with dSPACE (installed with dSPACE hardware)hardware)

Experimental Setup.Experimental Setup.

Solar Module Solar Module

Isc=2.9A.Isc=2.9A.Voc=20V.Voc=20V.Power=38W.Power=38W.Vp=17.7V.Vp=17.7V.Ip=2.2A.Ip=2.2A.

Hardware Setup.Hardware Setup.

SchematicSchematic

0

D 1

M 1

L o u t

C o u tR L o a d

C in

R 5

R 4

R c u rre n t _ s e n s e

PV module.

SCHEMATIC OF BUCK CONVERTER.

TRIGGERINGPULSES

Personel ComputerWith dSPACE cardPanel

Voltage

PanelCurrent

ResultsResults

Results.Results.

ResultsResults

Results.Results.

ConclusionsConclusions

Power output of the module improves Power output of the module improves by about 100%( doubles) with the PPT by about 100%( doubles) with the PPT system than it was with out the MPPT system than it was with out the MPPT system.system.

The power delivered to the load in The power delivered to the load in case of step-down and step up case of step-down and step up converter is almost same. Only converter is almost same. Only difference that was observed was with difference that was observed was with the output voltage. the output voltage.

ConclusionsConclusions

Temperature of the module is an Temperature of the module is an important parameter. The power output important parameter. The power output of the module changes by about 0.5% for of the module changes by about 0.5% for every degree rise in temperature. So a every degree rise in temperature. So a 38W module gives only a power of about 38W module gives only a power of about 29W peak29W peak

The module placement also plays an The module placement also plays an important role in power output. Module is important role in power output. Module is kept in south facing. Buts its elevation kept in south facing. Buts its elevation angle must be adjusted every month to angle must be adjusted every month to get high power output.get high power output.

Future Scope.Future Scope.

Perturb and observe (P&O) Perturb and observe (P&O) algorithm for peak power tracking is algorithm for peak power tracking is explained in the present report. explained in the present report.

Simulink models of algorithms other Simulink models of algorithms other than P&O can be developed and than P&O can be developed and tested on the real time platform tested on the real time platform using the dSPACEusing the dSPACERR. .

Microcontroller based dedicated Microcontroller based dedicated MPPT controller can be carried out MPPT controller can be carried out using the same algorithm.using the same algorithm.

Future Scope.Future Scope.

A whole stand alone system A whole stand alone system including the MPPT system and the including the MPPT system and the inverter system can be developed inverter system can be developed using the dSPACEusing the dSPACERR..

References.References.

1].Chihchiang Hua, 1].Chihchiang Hua, ,,Jongrong Lin, and Jongrong Lin, and Chihming Shen,“Implementation of a DSP-Chihming Shen,“Implementation of a DSP-Controlled Photovoltaic System with Peak Controlled Photovoltaic System with Peak Power Tracking”,IEEE TRANSACTIONS ON Power Tracking”,IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 45, NO. INDUSTRIAL ELECTRONICS, VOL. 45, NO. 1, FEBRUARY 1998 pp 99-107.1, FEBRUARY 1998 pp 99-107.

2].Chihchiang Hua and Chihming Shen, 2].Chihchiang Hua and Chihming Shen, “Control of DC/DC Converters for Solar “Control of DC/DC Converters for Solar Energy System with Maximum Power Energy System with Maximum Power Tracking”. Tracking”.

References.References. 3]. K. H. Hussein 3]. K. H. Hussein et al, et al, “Maximum “Maximum

photovolatic power tracking: An photovolatic power tracking: An algorithm for rapidly changing algorithm for rapidly changing atmospheric conditions,” atmospheric conditions,” Proc. Inst.Proc. Inst. Elect. Eng. Elect. Eng. vol. 142, pt. G, no. 1, pp. 59–vol. 142, pt. G, no. 1, pp. 59–64, Jan. 1995.64, Jan. 1995.

4].C.R. Sullivan and M.J. Powers,“A 4].C.R. Sullivan and M.J. Powers,“A High-Efficiency Maximum Power Point High-Efficiency Maximum Power Point Tracking for Photovoltaic Arrays in a Tracking for Photovoltaic Arrays in a Solar-Power Race Vehicle”, IEEE Solar-Power Race Vehicle”, IEEE PESC‘93, 1993, pp.574-580.PESC‘93, 1993, pp.574-580.

References.References. 5].B.K. Bose, P.M. Szczesny and R.L. 5].B.K. Bose, P.M. Szczesny and R.L.

Steigerwald,,“Microcomputer Control of Steigerwald,,“Microcomputer Control of a Residential Photovoltaic Power a Residential Photovoltaic Power Condictioning System”, IEEE Trans. on Condictioning System”, IEEE Trans. on Industry Applications, vol. IA-21, no. Industry Applications, vol. IA-21, no. 5,Sep. 1985, ppll82-1191.5,Sep. 1985, ppll82-1191.

6].Xuejun Liu and A.C.Lopes,,“An 6].Xuejun Liu and A.C.Lopes,,“An Improved Perturbation and Observe Improved Perturbation and Observe Maximum Power Point Tracking Maximum Power Point Tracking Algorithm for PV Arrays”Algorithm for PV Arrays”

IEEE PESC ‘2004, pp.2005-2010.IEEE PESC ‘2004, pp.2005-2010.

References.References. 7].D. P. Hohm, M. E. Ropp,“Comparative 7].D. P. Hohm, M. E. Ropp,“Comparative

Study of Maximum Power Point Tracking Study of Maximum Power Point Tracking Algorithms Using an Experimental, Algorithms Using an Experimental, Programmable, Maximum Power Point Programmable, Maximum Power Point Tracking Test Bed”,IEEE,2000.pp.1699-Tracking Test Bed”,IEEE,2000.pp.1699-1702.1702.

8]. Mohammad A. S. Masoum, Hooman 8]. Mohammad A. S. Masoum, Hooman Dehbonei, and Ewald F. Fuchs, Dehbonei, and Ewald F. Fuchs, “Theoretical and Experimental Analyses “Theoretical and Experimental Analyses of Photovoltaic Systems With Voltage- of Photovoltaic Systems With Voltage- and Current-Based Maximum Power-and Current-Based Maximum Power-Point Tracking”, IEEE TRANSACTIONS Point Tracking”, IEEE TRANSACTIONS ON ENERGY CONVERSION, VOL. 17, ON ENERGY CONVERSION, VOL. 17, NO. 4, DECEMBER 2002.NO. 4, DECEMBER 2002.

ReferencesReferences

9]. T. Markvart, “ Solar Electricity”, 9]. T. Markvart, “ Solar Electricity”, John Wiley & Sons,1994.John Wiley & Sons,1994.

10]. N. Mohan 10]. N. Mohan et al., et al., Power Power Electronics—Converter, Applications, Electronics—Converter, Applications, and Design.and Design.

New York: Wiley, 1995.New York: Wiley, 1995. 12]. 12]. www.ieeexplore.ieee.orgwww.ieeexplore.ieee.org 13]. 13]. www.mathworks.comwww.mathworks.com 14]. 14]. www.dspace.dewww.dspace.de

Questions?Questions?

??

Thank You.Thank You.

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