Analysis and design of grid connected photovoltaic systems
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This paper proposes a new architecture for grid-connected photovoltaic systems called multiple-integrated converter modules sharing an unfolding full-bridge inverter with a pseudo dc link (MIPs). The proposed MIPs configuration can improve power conversion efficiency, reduce control circuit complexity, and lower costs. It consists of distributed flyback DC-DC converters and an unfolding full-bridge inverter with an AC filter. Experimental results validate the performance of the proposed design and confirm over 99% maximum power point tracking efficiency.
Analysis and design of grid connected photovoltaic systems
- 2. ABSTRACT In this paper describes the architecture of multiple-integrated converter modules sharing an unfolding full-bridge inverter with a pseudo dc link (MIPs) is proposed for grid-connected photovoltaic systems in this paper. The proposed configuration can improve the power conversion, the control circuit complexity, and the cost competitiveness. The proposed MIP is composed of distributed flyback dc–dc converters (DFCs) and an unfolding full-bridge inverter with an ac filter. The DFCs can eliminate the shading effect by using the individual maximum power point tracking. In conventional flyback-type single-phase utility-interactive inverters, discontinuous conduction mode and boundary conduction mode are popular because of the inherent constant current-source characteristics more desirable for grid connection and of the simple procedures for the controller design.
- 3. However, the operating mode suffers from a large current stress of the circuit components, which leads to the low power efficiency. To avoid this, the DFCs operate under continuous conduction mode that allows reduced current stresses and increased power efficiency, as well as low material cost. The current control loop of the converters employs primary-side regulation contributing to improvement of dynamics as well as the cost reduction significantly due to the elimination of the high-linearity photo coupler device. Development of a new dc-current loop that maintains the level of dc-current injection into the grid within the levels stipulated will be dealt as well. The performance validation of the proposed design is confirmed by experimental results.
- 4. INTRODUCTION The Maximum Power Point Tracker (MPPT) is needed to optimize the amount of power obtained from the photovoltaic array to the power supply. The output of a solar module is characterized by a performance curve of voltage versus current, called the I-V curve. See Figure 1. The maximum power point of a solar module is the point along the I-V curve that corresponds to the maximum output power possible for the module. This value can be determined by finding the maximum area under the current versus voltage curve. The objective of the project is to design a Maximum Power Point Tracking (MPPT) charge collecter which operate with photovoltaic module and produce maximum power to solar power collector. This component optimized the amount of power obtained from the photovoltaic array and charged the power supply.
- 5. The maximum power point tracker (MPPT) is now prevalent in grid-tied PV power systems and is becoming more popular in stand-alone systems. It should not be confused with sun trackers, mechanical devices that rotate and/or tilt PV modules in the direction of sun. MPPT is a power electronic device interconnecting a PV power source and a load, maximizes the power output from a PV module or array with varying operating conditions, and therefore maximizes the system efficiency. MPPT is made up with a switch-mode DC-DC converter and a controller. For grid-tied systems, a switch-mode inverter sometimes fills the role of MPPT. Otherwise, it is combined with a DC-DC converter that performs the MPPT function. In addition to MPPT, the system could also employ a sun tracker. According to the data in reference, the single-axis sun tracker can collect about 40% more energy than a seasonally optimized fixed-axis collector in summer in a dry climate. In winter, however, it can gain only 20% more energy. The effect of sun tracker is smaller because a larger fraction of solar irradiation is diffuse. It collects 30% more energy in summer, but the gain is less than 10% in winter.
- 6. HOW DOES IT WORK? The inputs of the MPPT consisted of the photovoltaic voltage and current outputs. The adjusted voltage and current output of the MPPT charges the power supply. See Figure. A microcontroller was utilized to regulate the integrated circuits (ICs) and calculate the maximum power point, given the output from the solar array. Hardware and software integration was necessary for the completion of this component.
- 7. LITERATURE SURVEY 1. T. V. Thang, N. M. Thao, Jong-Ho Jang, and Joung-Hu Park, Senior Member, IEEE “Analysis and Design of Grid-Connected Photovoltaic Systems With Multiple-Integrated Converters and a Pseudo-DC-Link Inverter:” IEEE Transactions On Industrial Electronics, VOL. 61, NO. 7, JULY 2014. 2. P.Dhandayuthabaani*, M.Hemalatha*, V.Gowtham*, M.Suresh, “An Improved Flyback Inverter for Photovoltaic Applications” International Journal of Advanced Research in Electrical, Electronics and Instrumentation Engineering, Vol. 4, Issue 3, March 2015. 3. Ali Ajami, Hossein Ardi, and Amir Farakhor, “A Novel High Step-up DC/DC Converter Based on Integrating Coupled Inductor and Switched-Capacitor Techniques for Renewable Energy Applications”, IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 30, NO. 8, AUGUST 2015.
- 8. EXISTING SYSTEM Existing system described an procedure to design a sliding controller for the PV system, which drives the PV voltage to follow a reference provided by an external MPPT algorithm. System used high power components so overall efficiency increased. The combination of the input capacitor current and the PV voltage error had occurred. The control system obtained in the sliding analysis indicated that a low-pass pre-filter had to be inserted between the MPPT module and the controller input, so that the usually large power was consumed and dissipated power increased. The controller parameters were calculated by solving a nonlinear set of equations.
- 9. PROPOSED SYSTEM In this paper, small-signal analysis and design guidelines of a MIP with a CCM flyback converter and an unfolding full bridge inverter have been proposed. A desirable feature of the work is the material-cost reduction from a new architecture of the dc-link multi module structure with the current and from a new analog-circuited dc-rejection controller. The output has two loads first one CFL bulb operates in AC and second one DC water pump motor has been used. The analog-circuited MPPT performance of the hardware prototype was mostly over 99%. Another issue is dc- current injection. To overcome the problem, a dc-rejection circuit that introduces a current reference waveform based on measurement of the dc component at grid current has been proposed. As a result, a dc-rejection circuit is applied to the MIP circuit, using costly persuasive devices. The proposed scheme achieves an acceptable dc-current level at the output of the MPPT system.
- 11. Circuit Diagram
- 12. DESCRIPTION The input of our design MPPT system is the DC power supply from the solar panel. The output of this system is the output voltage to the load supplying 80 W to the DC motor. The power that is harvested from solar panel is maximized using the MPPT system by using P&O algorithm. Basically, to have the maximum power transfer to the load, an impedance matching circuit design is required. Hence, our overall design can be divided into four simple stages as shown. The input solar panel is fed into the MPPT system and impedance matching to have the desired output at the load.
- 13. 1.INVERTER Most standard appliances are designed to accept only AC (alternating current) voltages because that's how electricity is supplied from the grid. In order to run an electronic device from a DC (direct current) source you obviously need to transform it into AC. A device that converts electricity from DC form to AC form using electronic circuits is known in power industry as inverter. Note that the same term is used in digital electronics for a circuit that switches the logic level of a signal. To avoid confusion, the device we are talking about is a power inverter. Its typical application is to convert a battery voltage into conventional residential AC. Inverters are used in a wide variety of applications from small car adapters to large grid-tie systems that can supply electricity to an entire home.
- 14. 2.BUCK AND BOOST CONVERTER A buck converter is a step-down DC to DC converter. Its design is similar to the step-up boost converter, and like the boost converter it is a switched-mode power supply that uses two switches (a transistor and a diode), an inductor and a capacitor. The operation of the buck converter is fairly simple, with an inductor and two switches (usually a transistor and a diode) that control the inductor. It alternates between connecting the inductor to source voltage to store energy in the inductor and discharging the inductor into the load. For the purposes of analysis it is useful to consider an idealised buck converter. In the idealised converter all the components are considered to be perfect. Specifically the switch and the diode have zero voltage drop when on and zero current flow when off and the inductor has zero series resistance. Further it is assumed that the input and output voltages do not change over the course of a cycle (this would imply the output capacitance being infinitely large).
- 15. INVERTOR AND BUCK BOOST CONVERTOR
- 16. 3.KA3525 PULSE WIDTH MODULATOR The KA3525 regulating pulse width modulator contains all of the control circuit necessary to implement switching regulators of either polarity transformer coupled DC to DC converters, transformer less polarity converters and voltage doublers, as well as other power control applications. This device includes a 5V voltage regulator capable of supplying up to 50mA to external circuit, a control amplifier, an oscillator, a pulse width modulator, a phase splitting flip-flop. FEATURES Complete PWM power control circuit Operation beyond 100KHz 2% frequency stability with temperature Total quiescent current less than 10mA Single ended or push-pull outputs Current limit amplifier provides external component protection On-chip protection against excessive junction temperature
- 17. COMPARISION: MPPT vs NON-MPPT
- 18. CONCLUSION In order to charge a power source at its maximum efficiency, a Maximum Power Point Tracker (MPPT) device is utilized. The MPPT design incorporated three systems – the Voltage Divider, Buck convertor, Solar Charging Unit, and Solar Array Protection. Although the final MPPT completely function as planned, so Maximum Power Point voltage was obtained. As the project came to an end, various changes could have been made which could benefit the design and implementation process. A smaller output range of the solar array would have helped to design a more efficient MPPT. Many problems with the component purchasing and software were encountered.
- 19. FUTURE WORK The non-renewable energy is running out nowadays, such as fossil fuels are depleting on earth. Therefore, changing to renewable energy source is a necessity. Solar energy will be the choice and it is easily acquired. However, most solar panel has low efficiency, so the MPPT system will help maximizing the power absorbed from the solar panel. Fast-switching components are necessary to operate the device intended for solar applications. The component choice is key in the design of the MPPT. High power efficiency is attained by carefully researching and selected the right components.
- 20. REFERENCES Chia S.L., Ahmad M.H., Ossen D.R. (2004). Impact of solar radiation on high-rise built form in tropical climate. Department Of Architecture, Faculty Of Built Environment, University Of Technology Malaysia. David C. H. and Yan H. L., 2000. Simple maximum power point tracker for photovoltaic arrays. Electronic Letters, Vol. 36, No. 11. Liu Y. H., Huang J. W. (2011). A fast and low cost analog maximum power point tracking method for low power photovoltaic systems. Solar Energy, 85, 2771-2780. Moorthy M. (2010). Performance of solar air-conditioning system using heat pipe evacuated tube collector. National Conference in Mechanical Engineering Research and Postgraduates Studies, 564-572. Muzathik A. M., Wan Nik W. B., Samo K. B. & Ibrahim M. Z. (2010). Hourly global solar radiation estimate on a horizontal plane. Journal of Physical Science,21(2), 51-66. Richard Corkish, Deo Prasad (2006) Integrated Solar Photovoltaics for Buildings. Journal of Green Building: Spring 2006, Vol.