Design of Fuzzy Logic Based Maximum Power Point Tracking Controller for Solar Array for Cloudy Weather Conditions

 

ABSTRACT:

This paper proposes Maximum Power Point Tracking (MPPT) of a photovoltaic system under variable temperature and solar radiation conditions using Fuzzy Logic Algorithm. The cost of electricity from the PV array is more expensive than the electricity from the other non-renewable sources. So, it is necessary to operate the PV system at maximum efficiency by tracking its maximum power point at any weather conditions 111. Boost converter increases output voltage of the solar panel and converter output voltage depends upon the duty cycle of the MOSFET present in the boost converter. The change in the duty cycle is done by Fuzzy logic controller by sensing the power output of the solar panel. The proposed controller is aimed at adjusting the duty cycle of the DC-DC converter switch to track the maximum power of a solar cell array. MATLABI Simulink is used to develop and design the PV array system equipped with the proposed MPPT controller using fuzzy logic 12][31. The results show that the proposed controller is able to track the MPP in a shorter time with less fluctuation. The complete hardware setup with fuzzy logic controller is implemented and the results are observed and compared with the system without MPPT (Fuzzy logic controller).

KEYWORDS:

  1. MPPT
  2. Fuzzy Logic Control
  3. DC-DC Converter,
  4. Photo voltaic systems.

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Block diagram of MPPT of PV array.

EXPECTED SIMULATION RESULTS:

 Fig. 2. Power Vs output voltage

Fig. 3. Voltage Vs Current output of solar panel

Fig. 4. Output voltage of the solar panel without MPPT.

Fig. 5. Output of the solar panel with MPPT FLC under cloudy weather conditions.

Fig. 6. PWM output when driven by FLC

 CONCLUSION:

This paper presents an intelligent control method of tracking maximum power and Simulation and hardware result show that proposed MPPT controller increases the efficiency of the PV array energy conversion efficiency. Results are compared with the panel without MPPT controller.

REFERENCES:

[1] Chetan Singh Solanki,” Solar Photo Voltaics “, PHI Learning pvt. Ltd ,2009.

[2] Bor-Ren Lin,”Analysis of Fuzzy Control Method Applied to DCDC Converter controf’ , IEEE Prowe .h g APK’93, pp. 22- 28,1993.

[3] Rohin M.Hillooda, Adel M.Shard,”A rule Based Fuzzy Logic controller for a PWM inverter in Photo Voltaic Energy Conversion Scheme”, IAS’SZ, PP.762-769, 1993.

[4] Pongsakor Takum, Somyot Kaitwanidvilai and Chaiyan Jettasen ; ‘Maximum POlVer Point Tracking using jilzzy logic control for photovoltaic systems.’ Proceedings Of International Multiconference of Engineers and Computer scientists ,Vol 2,March 2011.

[5] M.S.Cheik , Larbes, G.F Kebir and A ZerguelTas; ‘Maximum power point tracking using a jilzzy logic control scheme.’; ‘Departementd’Electronique’, Revue des Energies Renouvelables, VoI.lO,No 32 , September 2007, pp 387-395

Backstepping Control of Smart Grid-Connected Distributed Photovoltaic Power Supplies for Telecom Equipment

ABSTRACT:

Backstepping controllers are obtained for distributed hybrid photovoltaic (PV) power supplies of telecommunication equipment. Grid-connected PV-based power supply units may contain dc–dc buck–boost converters linked to single-phase inverters. This distributed energy resource operated within the self consumption concept can aid in the peak-shaving strategy of ac smart grids. New backstepping control laws are obtained for the single-phase inverter and for the buck–boost converter feeding a telecom equipment/battery while sourcing the PV excess power to the smart grid or to grid supply the telecom system. The backstepping approach is robust and able to cope with the grid nonlinearity and uncertainties providing dc input current and voltage controllers for the buck–boost converter to track the PV panel maximum power point, regulating the PV output dc voltage to extract maximum power; unity power factor sinusoidal ac smart grid inverter currents and constant dc-link voltages suited for telecom equipment; and inverter bidirectional power transfer. Experimental results are obtained from a lab setup controlled by one inexpensive dsPIC running the sampling, the backstepping and modulator algorithms. Results show the controllers guarantee maximum power transfer to the telecom equipment/ac grid, ensuring steady dc-link voltage while absorbing/injecting low harmonic distortion current into the smart grid.

KEYWORDS:

  1. Backstepping
  2. Buck–boost converter
  3. Dc/ac converter
  4. MPPT
  5. Self-consumption
  6. Smart grids

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

 image001

Fig. 1. PV distributed hybrid self-consumption system and telecom load.

EXPECTED SIMULATION RESULTS:

 image002

 Fig. 2. MPPT operation.

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Fig. 3. Voltage and current waveforms when there is a change from inverter to rectifier.

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Fig. 4. (a)Voltage and current waveforms when there is a change from inverter to rectifier. (b) Center part zoom of (a).

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Fig. 5. Voltage and current waveforms when the load requires 25 W.

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Fig. 6. Voltage and current waveforms when the load requires 62 W.

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Fig. 7. DC–AC converter input power.

 CONCLUSION:

This paper proposes a novel backstepping controller for a PV panel feeding a buck–boost converter, and dc linked to a telecom load and a single-phase ac–dc converter connected to a smart grid, configuring a subset of a distributed hybrid photovoltaic power supply for telecom equipments within the self-consumption concept. This setup absorbs/injects nearly sinusoidal (THD = 1.6%, lower than the 3% required by the standards) grid currents at near unity power factor and the self consumption can contribute to the smart grid peak power shaving strategy.

New nonlinear backstepping control laws were obtained for the input voltage of the buck–boost converter, thus achieving MPP operation (MPPT efficiency between 98.2% and 99.9%) and for the dc–ac converter regulating the dc telecom load voltage and controlling the ac grid current. All the control laws, fixed frequency converter modulators, voltage and current sampling, and grid synchronization have been implemented using a low-cost dsPIC30F4011 microcontroller.

Obtained experimental results show the performance of the PV self-consumption system using the backstepping control method. Results show the system dynamic behavior when the dc–ac converter changes operation from inverter to rectifier to adapt itself to the telecom load requirements. The robustness of the control laws has been tested as well. Capacitance of real capacitors can vary almost ten times around the rated value, while inductances can vary from 30% to nearly 300% of the rated value.

 REFERENCES:

[1] N. Femia, G. Petrone, G. Spagnuolo, and M. Vitelli, Power Electronics and Control Techniques for Maximum Energy Harvesting in Photovoltaic Systems. Boca Raton, FL, USA: CRC Press, 2013.

[2] A.Maki and S. Valkealahti, “Effect of photovoltaic generator components on the number of MPPs under partial shading conditions,” IEEE Trans. Energy Convers., vol. 28, no. 4, pp. 1008–1017, Dec. 2013.

[3] Epia Org. (2013, Jul.). Self-consumption of PV electricity—Position paper. [Online]. Available:http://www.epia.org/fileadmin/user_upload/Position_Papers/Self_and_direct_consumption_-_position_paper_-_final _version.pdf

[4] SunEdison. (2011, Nov.). Enabling the European consumer to generate power for self-consumption. [Online]. Available: http://www. sunedison.com/wps/wcm/connect/35bfb52a-ec27-4751-8670-fe6e807e8063/SunEdison_PV_Self  consumption_Study_high_resolution_%2813_ Mb%29.pdf?MOD=AJPERES

[5] A. Nourai, R. Sastry, and T.Walker, “A vision & strategy for deployment of energy storage in electric utilities,” in Proc. IEEE Power Energy Soc. Gen. Meeting, 2010, pp. 1–4.

Grid-Connected PV Array with Supercapacitor Energy Storage System for Fault Ride Through

ABSTRACT:

A fault ride through, power management and control strategy for grid integrated photovoltaic (PV) system with supercapacitor energy storage system (SCESS) is presented in this paper. During normal operation the SCESS will be used to minimize the short term fluctuation as it has high power density and during fault at the grid side it will be used to store the generated power from the PV array for later use and for fault ride through. To capture the maximum available solar power, Incremental Conductance (IC) method is used for maximum power point tracking (MPPT). An independent P-Q control is implemented to transfer the generated power to the grid using a Voltage source inverter (VSI). The SCESS is connected to the system using a bi-directional buck boost converter. The system model has been developed that consists of PV module, buck converter for MPPT, buck-boost converter to connect the SCESS to the DC link. Three independent controllers are implemented for each power electronics block. The effectiveness of the proposed controller is examined on Real Time Digital Simulator (RTDS) and the results verify the superiority of the proposed approach.

KEYWORDS:

  1. Active and reactive power control
  2. Fault ride through
  3. MPPT
  4. Photovoltaic system
  5. RTDS Supercapacitor
  6. Energy storage

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

image001

Fig.1. Grid connected PV system with energy storage

 EXPECTED SIMULATION RESULTS:

 image002

Fig.2. Grid voltage after three phase fault is applied

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Fig.3. PV array power PPV with SCESS and with no energy storage

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Fig.4. Grid active power Pg for a three phase fault with and without energy storage

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Fig.5.SCESS power PSC for the applied fault on the grid side

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Fig.6. Grid reactive power Qg during three phase fault

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Fig.7. DC link voltage for the applied fault

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Fig.8. PV array voltage VPV during three phase fault

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Fig.9. MPPT output voltage Vref for the applied fault

CONCLUSION:

This paper presents grid connected PV system with supercapacitor energy storage system (SCESS) for fault ride through and to minimize the power fluctuation. Incremental conductance based MPPT is implemented to track the maximum power from the PV array. The generated DC power is connected to the grid using a buck converter, VSI, buck-boost converter with SCESS. The SCESS which is connected to the DC link controls the DC link voltage by charging and discharging process. A P-Q controller is implemented to transfer the DC link power to the grid. During normal operation the SCESS minimizes the fluctuation caused by change in irradiation and temperature. During a grid fault the power generated from the PV array will be stored in the SCESS. The SCESS supplies both active and reactive power to ride through the fault. RTDS based results have shown the validity of the proposed controller.

REFERENCES:

[1] T. Esram, P.L. Chapman, “Comparison of Photovoltaic Array Maximum Power Point Tracking Techniques,” IEEE Transaction on Energy Conversion, vol.22, no.2, pp.439-449, June 2007

[2] J. M. Enrique, E. Durán, M. Sidrach-de-Cardona, and J. M. Andújar,“Theoretical assessment of the maximum power point tracking efficiency of photovoltaic facilities with different converter topologies,” Sol. Energy, vol. 81, no. 1, pp. 31–38, Jan. 2007.

[3] W. Xiao, N. Ozog, and W. G. Dunford, “Topology study of photovoltaic interface for maximum power point tracking,” IEEE Trans. Ind. Electron., vol. 54, no. 3, pp. 1696–1704, Jun. 2007.

[4] J. L. Agorreta, L. Reinaldos, R. González, M. Borrega, J. Balda, and L. Marroyo, “Fuzzy switching technique applied to PWM boost converter operating in mixed conduction mode for PV systems,” IEEE Trans. Ind. Electron., vol. 56, no. 11, pp. 4363– 4373, Nov. 2009.

[5] A.Schneuwly, “Charge ahead [ultracapacitor technology and applications]”, IET Power Engineering Journal, vol.19, 34-37, 2005.

 

A Three-Phase Grid Tied SPV System with Adaptive dc link voltage for CPI voltage variations

 

ABSTRACT:

This paper deals with a three-phase two-stage grid tied SPV (solar photo-voltaic) system. The first stage is a boost converter, which serves the purpose of MPPT (maximum power point tracking) and feeding the extracted solar energy to the DC link of the PV inverter, whereas the second stage is a two-level VSC (voltage source converter) serving as PV inverter which feeds power from a boost converter into the grid. The proposed system uses an adaptive DC link voltage which is made adaptive by adjusting reference DC link voltage according to CPI (common point of interconnection) voltage. The adaptive DC link voltage control helps in the reduction of switching power losses. A feed forward term for solar contribution is used to improve the dynamic response. The system is tested considering realistic grid voltage variations for under voltage and over voltage. The performance improvement is verified experimentally. The proposed system is advantageous not only in cases of frequent and sustained under voltage (as in the cases of far radial ends of Indian grid) but also in case of normal voltages at CPI. The THD (total harmonics distortion) of grid current has been found well under the limit of an IEEE-519 standard.

KEYWORDS:

  1. Adaptive DC link
  2. MPPT
  3. Overvoltage
  4. Solar PV
  5. Two-stage
  6. Three phase
  7. Under voltage

 SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

 image001

Fig. 1. System configuration.

 CONTROL SYSTEM

image002

Fig. 2. Block diagram for control approach.

 EXPECTED SIMULATION RESULTS:

 image003

 Fig. 3. Simulated performance for, (a) change in solar insolation without feedforward for PV contribution,

image004

(b) change in solar insolation with feed forward for PV contribution,

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(c) normal to under voltage (415 V to 350 V),

image006

(d) CPI voltage variation from normal to over voltage (415 V to 480 V).

CONCLUSION:

A two-stage system has been proposed for three-phase grid connected solar PV generation. A composite InC based MPPT algorithm is used for control of the boost converter. The performance of proposed system has been demonstrated for wide range of CPI voltage variation. A simple and novel adaptive DC link voltage control approach has been proposed for control of grid tied VSC. The DC link voltage is made adaptive with respect to CPI voltage which helps in reduction of losses in the system. Moreover, a PV array feed forward term is used which helps in fast dynamic response. An approximate linear model of DC link voltage control loop has been developed and analyzed considering feed forward compensation. The PV array feed forward term is so selected that it is to accommodate for change in PV power as well as for CPI voltage variation. A full voltage and considerable power level prototype has verified the proposed concept. The concept of adaptive DC link voltage has been proposed for grid tied VSC for PV application however, the same concept can be extended for all shunt connected grid interfaced devices such as, STATCOM, D-STATCOM etc. The proposed system yields increased energy output using the same hardware resources just by virtue of difference in DC link voltage control structure. The THDs of the grid currents and voltages are found less than 5% (within IEEE-519 standard). The simulation and experimental results have confirmed the feasibility of proposed control algorithm.

 REFERENCES:

[1] M. Pavan and V. Lughi, “Grid parity in the Italian commercial and industrial electricity market,” in Proc. Int. Conf. Clean Elect. Power (ICCEP’13), 2013, pp. 332–335.

[2] M. Delfanti, V. Olivieri, B. Erkut, and G. A. Turturro, “Reaching PV grid parity: LCOE analysis for the Italian framework,” in Proc. 22nd Int. Conf. Exhib. Elect. Distrib. (CIRED’13), 2013, pp. 1–4.

[3] H.Wang and D. Zhang, “The stand-alone PV generation system with parallel battery charger,” in Proc. Int. Conf. Elect. Control Eng. (ICECE’10), 2010, pp. 4450–4453.

[4] M. Kolhe, “Techno-economic optimum sizing of a stand-alone solar photovoltaic system,” IEEE Trans. Energy Convers., vol. 24, no. 2, pp. 511–519, Jun. 2009.

[5] D. Debnath and K. Chatterjee, “A two stage solar photovoltaic based stand alone scheme having battery as energy storage element for rural deployment,” IEEE Trans. Ind. Electron., vol. 62, no. 7, pp. 4148–4157, Jul. 2015.

Control Scheme for a Stand-Alone Wind Energy Conversion System

 

ABSTRACT

Present energy need heavily relies on the conventional sources. But the limited availability and steady increase in the price of conventional sources has shifted the focus toward renewable sources of energy. Of the available alternative sources of energy, wind energy is considered to be one of the proven technologies. With a competitive cost for electricity generation, wind energy conversion system (WECS) is nowadays deployed formeeting both grid-connected and stand-alone load demands. However, wind flow by nature is intermittent. In order to ensure continuous supply of power suitable storage technology is used as backup. In this paper, the sustainability of a 4-kW hybrid of wind and battery system is investigated for meeting the requirements of a 3-kW stand-alone dc load representing a base telecom station. A charge controller for battery bank based on turbine maximum power point tracking and battery state of charge is developed to ensure controlled charging and discharging of battery. The mechanical safety of the WECS is assured by means of pitch control technique. Both the control schemes are integrated and the efficacy is validated by testing it with various load and wind profiles in MATLAB/SIMULNIK.

 KEYWORDS

  1. Maximum power point tracking (MPPT)
  2. Pitch control
  3. State of charge (SoC)
  4. Wind energy conversion system (WECS).

SOFTWARE: Matlab/Simulink

BLOCK DIAGRAM:

image001

Fig. 1. Layout of hybrid wind–battery system for a stand-alone dc load.

SIMULATION RESULTS:

image002

Fig. 2. (a) WT and (b) battery parameters under the influence of gradual variation of wind speed.

image003

Fig. 3. (a)WT and (b) battery parameters under the influence of step variation of wind speed.

image004

Fig. 4. (a) WT and (b) battery parameters under the influence of arbitrary variation of wind speed.

CONCLUSION

The power available from a WECS is very unreliable in nature. So, a WECS cannot ensure uninterrupted power flow to the load. In order to meet the load requirement at all instances, suitable storage device is needed. Therefore, in this paper, a hybrid wind-battery system is chosen to supply the desired load power. To mitigate the random characteristics of wind flow the WECS is interfaced with the load by suitable controllers. The control logic implemented in the hybrid set up includes the charge control of battery bank using MPPT and pitch control of the WT for assuring electrical and mechanical safety. The charge controller tracks the maximum power available to charge the battery bank in a controlled manner. Further it also makes sure that the batteries discharge current is also within the C/10 limit. The current programmed control technique inherently protects the buck converter from over current situation. However, at times due to MPPT control the source power may be more as compared to the battery and load demand. During the power mismatch conditions, the pitch action can regulate the pitch angle to reduce the WT output power in accordance with the total demand. Besides controlling the WT characteristics, the pitch control logic guarantees that the rectifier voltage does not lead to an overvoltage situation. The hybrid wind-battery system along with its control logic is developed in MATLAB/SIMULINK and is tested with various wind profiles. The outcome of the simulation experiments validates the improved performance of the system.

 REFERENCES

  • [1] Sahin, “Progress and recent trends in wind energy,” Progress in Energy Combustion Sci., vol. 30, no. 5, pp. 501–543, 2004.
  • [2] D. Richardson and G. M. Mcnerney, “Wind energy systems,” Proc. IEEE, vol. 81, no. 3, pp. 378–389, Mar. 1993.
  • [3] Saidur, M. R. Islam, N. A. Rahim, and K. H. Solangi, “A review on global wind energy policy,” Renewable Sustainable Energy Rev., vol. 14, no. 7, pp. 1744–1762, Sep. 2010.

Solar Grid-Tied Inverter, with Battery Back-up, for Efficient Solar Energy Harvesting

ABSTRACT:

Solar Grid-Tied Inverter system is an electricity generating system that is connected to the utility grid. This paper discusses the design of a Grid-Tied Inverter (GTI). The first stage is Maximum Power Point Tracking (MPPT) which is implemented using perturb and observe algorithm. Then push pull converter is used to convert DC output from MPPT stage to 330V dc. This DC voltage is then converted into AC voltage using full-wave inverter topology employing unipolar SPWM technique. Then synchronization is achieved between grid and photovoltaic system. Finally, power flow control mechanism controls the power flow from GTI system to the grid and the house load.

KEYWORDS:

  1. Grid-tied inverter
  2. SPWM
  3. Power flow
  4. MPPT

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

image001

Figure 1. Cuk converter.

image002

Figure 2. Full wave inverter topology .

EXPECTED SIMULATION RESULTS:

 image003

Figure 3. Inverter output before filter

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Figure 4. Inverter output after filter.

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Figure 5. Simulink circuit to demonstrate power flow.

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Figure 6. GTI output power.

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Figure 7. Grid output power.

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Figure 8. Power through inductor.

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Figure 9. GTI output power.

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Figure 10. Grid output power.

image011

Figure 11. Power through inductor.

REFERENCES:

[1] Power Electronics: Circuits, Devices and Applications, 3/E by M. H. Rashid, Prentice Hall, 2004J. Clerk Maxwell, A Treatise on Electricity and Magnetism, 3rd ed., vol. 2. Oxford: Clarendon, 1892, pp.68–73.

[2] Electric Machinery Fundamentals by Stephen J. Chapman, 4th Edition, McGraw-Hill, 2005K. Elissa, “Title of paper if known,” unpublished.

[3] M. A. Salam, Fundamentals of Power Systems, Alpha Science Oxford, UK International Ltd., 2009.

[4] T. Kwang and S. Masri, “Grid Tie Photovoltaic Inverter for Residential Application,” Modern Applied Science, vol. 5, No. 4, Aug. 2011, pp. 3-4, doi:10.5539/mas.v5n4p200

 

 

Modeling and Simulation of a Stand-alone Photovoltaic System

 

 ABSTRACT:

In the future solar energy will be very important energy source. More than 45% of necessary energy in the world will be generated by photovoltaic module. Therefore it is necessary to concentrate our forces in order to reduce the application costs and to increment their performances. In order to reach this last aspect, it is important to note that the output characteristic of a photovoltaic module is nonlinear and changes with solar radiation and temperature. Therefore a maximum power point tracking (MPPT) technique is needed to track the peak power in order to make full utilization of PV array output power under varying conditions. This paper presents two widely-adopted MPPT algorithms, perturbation & observation (P&O) and incremental conductance (IC). These algorithms are widely used in PV systems as a result of their easy implementation as well as their low cost. These techniques were analyzed and their performance was evaluated by using the Matlab tool Simulink.

 

KEYWORDS:

  1. Photovoltaic system
  2. MPPT
  3. Perturbation and Observation
  4. Incremental conductance

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

image002

Fig. 1. Block diagram of the stand-alone PV system.

CIRCUIT DIAGRAM

image004

Fig. 2. Model of the photovoltaic module

image006

Fig. 3. Schematic diagram of a DC Buck-Boost converter.

 EXPECTED SIMULATION RESULTS:

 image008

Fig. 4. Output current of PV module

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Fig. 5. Output voltage of PV module

image012

Fig. 6 Output power of PV module

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Fig. 7. Output current of MPPT+DC-DC converter

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Fig. 8. Output voltage of MPPT+DC-DC converter

image018

Fig. 9. Output power of MPPT+DC-DC converter

image020

Fig 10 : PV-Output power with and without MPPT+DC-DC converter

image022

Fig. 11. Output current of MPPT+DC-DC converter

image024

Fig. 12. Output voltage of MPPT+DC-DC converter

image026

Fig. 13. Output power of MPPT+DC-DC converter

image028

Fig. 14. PV-Output power with and without MPPT+DC-DC converter

CONCLUSION:

In this work, we presented a modeling and simulation of a stand-alone PV system. One-diode model for simulation of PV module was selected; Buck-Boost converter is studied and applied to test the system efficiency. Two Maximum Power Point Tracking techniques, P&O and IC, are presented and analyzed. The proposed system was simulated using the mathematical equations of each component in Matlab/Simulink. The simulation analysis shows that P&O method is simple, but has considerable power loss because PV module can only run in oscillation way around the maximum power point. IC method has more precise control and faster response, but has correspondingly higher hardware requirement. In practice, in order to achieve maximum efficiency of photovoltaic power generation, a reasonable and economical control method should be chosen. The following of this work is based on optimizing the performance of PV modules and stand-alone systems using more efficient algorithms to minimize the influence of the meteorological parameters on the PV energy production.

 REFERENCES:

[1] A.KH. Mozaffari Niapour, S. Danyali, M.B.B. Sharifian, M.R. Feyzi, “Brushless DC motor drives supplied by PV power system based on Zsource inverter and FL-IC MPPT controller”, Energy Conversion and Management 52, pp. 3043–3059, 2011.

[2] Reza Noroozian, Gevorg B. Gharehpetian, “An investigation on combined operation of active power filter with photovoltaic arrays”, International Journal of Electrical Power & Energy Systems, Vol. 46, Pages 392-399, March 2013.

[3] N. Femia, D. Granozio, G. Petrone, G. Spaguuolo, and M. Vitelli, “Optimized one-cycle control in photovoltaic grid connected applications”, IEEE Trans. Aerosp. Electron. Syst., Vol. 42, pp. 954- 972, 2006.

[4] T. L. Kottas, Y. S. Boutalis, and A. D. Karlis, “New maximum power point tracker for PV arrays using fuzzy controller in close cooperation with fuzzy cognitive net-work”, IEEE Trans. Energy Conv., Vol. 21, pp. 793–803, 2006.

[5] Mohamed A. Eltawil, Zhengming Zhao, “MPPT techniques for photovoltaic applications”, Renewable and Sustainable Energy Reviews, Vol. 25, P. 793-813, 2013.