An Effective and High Performance Approach of

7 downloads 0 Views 510KB Size Report
Solar panel provides peak output power when works at MPP. ... This technique make DC-DC converter very essential for the .... Fig: 13: PV Output Power at 1000W/m2 and 400W/m2 ... [9] ALTENER/GREENPRO: “Energia Fotovoltaica:Manual.
Ayushi Vaishy, et al International Journal of Research in Electronics & Communication Engineering [Volume 1, Issue 1, April 2013]

An Effective and High Performance Approach of Charging the Mobile Phones by using SMS with MPPT Technology Ms.Ayushi Vaishy1, Dr.Ajita Pathak2, Mr.Rajinder Tiwari3 Department of Electronics & Electrical Engineering, Amity University Uttar Pradesh, Lucknow 1 [email protected], 2 [email protected], [email protected]  Abstract - People who are living off grid can now charge their mobile phone just by sending an message by their mobile phone. It is possible by the solar powered cell phone charging station. This charging station is start working when it receives a message of charging the mobile by the user. This technology is very useful for the rural areas of developing countries where the supply of electricity is uncertain. It is the cheapest method found so far to charge mobile for rural areas. Rural areas need stronger signals from cell phones because there are few number of tower nearby. In this technique battery is charged by the solar panel. The battery extract the power to charge from the solar power charging station by a technique called Maximum Power Point Tracking (MPPT). Power output of solar panel depends on the environmental conditions like temperature, sunlight and the resistance of the circuit connected to it MPPT changes the resistance and monitors the conditions to get maximum possible power output within given time. Device important part is the way stored power is used to charge the phone. When a customer sends a text message to the device on receiving the message an LED above the socket of the battery starts lightning it indicates that the stored power is ready to charge the phone.

Large amount of power fed to the system will not be able to handled by the battery voltage in this way one can be unable to receive proper amount of power. If we transmit the data wirelessly than it will consume large amount of output power. In solar panels we use limited amount of power supply. On operating solar panels maximum power point and by intelligently using the amount of power from the panels energy can be consumed usefully When there is no sunlight and solar panel is not producing energy and providing to the cell phones then the electricity in the battery will flow in backward direction through the solar energy panel. MPPT in this situation disconnect the circuit to stop the reverse flow. Solar panels have relation between radiation, temperature and resistance by which an output efficiency produced which will be analysed by an I-V curve. By the proper resistance maximum power can be obtained in the certain circumstance which is the main purpose of MPPT technology.

Keywords - Solar powered cell phone charging station, MPPT, SMS Technique, Photo-voltaic Cell, Induction Procedure.

I. INTRODUCTION TO MAXIMUM POWER POINT TRACKING (MPPT) TECHNIQUE To maximize the output power it is necessary to continuously track the maximum power point of the system. MPPT stands for maximum power point tracking or tracker. MPPT are used with solar energy panels. When under given circumtances the solar energy panel are riches at its maximum electrical threshold level than it is known as maximum power point. The maximum power point will be decided by the sunnier day or cloudier day. Due to the uncertainty of sun light the maximum power point also will not be fixed. Because of the fluctuation in level of sun energy the capacity of solar energy panel will also be reduce.

Fig.1: Graph of solar panel’s MPP In MPPT technology we basically work with power and voltage. The maximum power point of a solar panel can be tracked. When solar panel is at its maximum power MPPT tracts that moment and also adjust the power accordingly to provide

Webpage: http://ijrece.org

Page 5

Ayushi Vaishy, et al International Journal of Research in Electronics & Communication Engineering [Volume 1, Issue 1, April 2013]

stability to the battery and increases electrical power production. MPPT stops battery from over charging and from system short circuiting. MPPT gernaly have digital display screen to view various readings. Solar panel provides peak output power when works at MPP. We can gernalize MPP as voltage and current corresponds to maximum output power obtained by the solar panel. The voltage of solar panel decreases as current drawn from the panel increases it is a characterstic of solar panels MPP technology. If the current drawn is very high than in this satuation voltage will be collapse and the power drawn from the panel will become too small. In fig output curren an output power versus output voltage graph of a particular solar panel has been taken. MPP is shown in between point 1 and point 2 on the power line. A horizontal line shows the in the graph is the output power is 90% of the MPP. The panels maximum power is between point 1 and point 2. There are many algorithms are used to calculate MPPT. Algorithm used in MPPT is based on to detect the maxima of the power. Radiance level at differ points of solar panel varied dependent on the temperature variation by which there are multiple local maxima in one system are generated. If a true maximum power point and local maximum power point is calculated than the efficiency and complexity of an algorithm can be defined easily and maximum electrical power will not be extracted from the panel. Perturb and Observe alogorithm is most commonly used in MPPT because of it is easy to implement on comparison of other algorithms. The aim behind this algorithm is to modify the voltage and current till the maximum power output get from the solar panel. If increasing in voltage increases the power output than voltage will be extent till the extant until the power will start decreasing. After this the voltage decreased to get bact the maximum power output. This satuation will go on until the satuation of maximum power point is obtained.

II. MAXIMUM POWER POINT TRACKING PHOTO-VOLTIC SYSTEM Photovoltic system is using as source of power for many application so far. It converts light energy to electrical energy with greater efficiency and lowest cost and to maximize the output power. PV system that lack MPPT is unable to operate at the efficient MPP. So the rated power of solar panel is difficult to analize when it is connected to the load. The Perturb and Observe (P& O) technique can be use to overcome with this problem of MPPT. According to this if the operating voltage of the PV system is Perturb in the given direction and if the power in the system is incrsing constantly than in this satuation the operating point will move towards the MPP so operating voltage must be further Perturb in the same direction and if the power drawn from the PV system decreses than the operating point will move away from the MPP and the direction of the operating voltage will be riversed. By adding P& O algorithm in the system it adds flexibility and find where the system can be easily constructed. Some components needed to use to overcome the problem occur in MPP when solar panel is connected to the load as solar panel, DC-DC converter, Digital controller, current sensor , voltage sensor and logic circuitry for connection.

Fig: 3: MPPT for PV system

Fig: 2: Flow chart of Perturb and Observe Tracking system It refered as hill climbing method because it depends on the rise of the curve of power against voltage below the maximum power point and the fall above that point. Petturb and Observe algorithm provides very high level of efficiency in MPPT.

Webpage: http://ijrece.org

DC-DC Converter: DC-DC converter which is a electronic circuit is used to convert direct current to one voltage level to another. This converters stores the input energy temporary and release the energy at the output at different current and voltage level. It is basically used as power converter and no energy is manufactured itself in the converter. It changes the energy at different impedance level and the output power is totally dependent on the input power.In this convertr a electrical load is connected to the solar panel which varies according to the output voltage of the panel. This changes is load changes the voltage and current characterstics so by controlling the converters characterstics the power can be controlled and obtain maximum power for the panel. This technique make DC-DC converter very essential for the MPPT. The MPPT Controler- Microcontroler provides control in the PV system. Controler used must be cost effective, good performance and must be flexible for the entire system. Controler must provide real time control applications which improve system efficiency, reliable and flexible when complex algorithms are used.

Page 6

Ayushi Vaishy, et al International Journal of Research in Electronics & Communication Engineering [Volume 1, Issue 1, April 2013]

I IN 

Fig 4: MPPT Circuit for a Pulsed Load There are few single-device, cost-effective solutions that operate from the wide voltage range of power-limited solar-panel inputs while efficiently providing a regulated output voltage, a quick start-up, and operation within 90% of the MPP. However, the Texas Instruments TPS62125 is one such device that accepts input voltages of up to 17 V, operates with efficiencies in excess of 90%, starts up in less than 1 ms, and has an enable input pin with a precise thresh-old that can be directly wired to the solar panel’s voltage for MPPT. This eliminates the need for an additional device to per-form this function. Figure 2 shows a complete solution. The voltage divider, formed by R1 and R2, is configured to turn on the power supply at Point 1 in Figure 1. Until the power supply is enabled, the device itself holds the node between R2 and R3 at ground potential. After the supply is enabled, the device releases this node, and R3 is then part of the voltage divider. When the solarpanel voltage falls to Point 2, the device turns off and holds the node low between R2 and R3 again. At this point, the panel voltage begins to rise again until it reaches the turn-on threshold. This provides a fully programmable turn-on and turn-off voltage that can be configured to any solar panel. The bulk input capacitor, C3, stores enough energy from the solar panel to power the load for the required duration and provides the charge for starting up the power supply. The panel delivers a current corresponding to its voltage to either the power supply or C3. When the power supply is off, the solar panel delivers its current to the capacitor. When the power supply is on, the capacitor and solar panel provide the necessary current to power the load. Since C3 merely stores energy and this energy is released over a relatively lengthy period of time, C3 can be a low-cost electrolytic capacitor. The first step in designing the MPPT circuit is determining the load’s power needs and then computing the amount of required bulk input capacitance based on these power requirements and the chosen solar panel. As an example, assume a remote sensing circuit requires 3.3 V at 250 mA (825 mW) for a duration of 15 ms. These are typical needs for a system that contains a measurement device, a micro-processor, and an RF transmitter. After the load’s power needs are determined, the required value for C3 is calculated. First, the input current required to power the load is found from Equation 1:

Webpage: http://ijrece.org

OutputPower VIN 

(1)

VIN is the average solar-panel voltage between Points 1 and 2 in Figure 1, and η is the power-supply efficiency at the given output power. Notice that the typical efficiency of the power supply at a VIN of about 7.8 V and an output power of 825 mW is around 87%. Using these numbers, IIN = 122 mA. This is much greater than what Figure 1 shows the solar panel to be capable of providing, so C3 must store enough energy to provide the remaining current for 15 ms. Equation 2 determines the required C3 value based on the load requirements and solar-panel characteristics:

C3 

I

IN



 I Panel  Avg   tON VP1  VP 2

(2)

VP1 and VP2 are the voltages at Points 1 and 2, which are respectively about 9 V and 6.5 V for this panel, and correspond to the voltage change across C3 as it discharges. The required load operating time, given by tON, is 15 ms. Finally, IPanel(Avg) is the average current from the solar panel when the panel is operated within 90% of its MPP. As seen in Figure 1, this current is about 19 mA. From Equation 2, it is determined that C3 should be greater than 618 µF. A 680-µF capacitor is used to provide some margin in the operating time. R1, R2, and R3 form a fully configurable voltage divider with hysteresis for the enable (EN) pin. Equations 3 and 4 are used to set the resistor values:

R  VP1  1.20V   1  1  R2 

(3)

 R1  VP 2  1.15V   1  R2  R3 

(4)

R1 is chosen first, and 1 MΩ is a good starting value. With this, R2 is calculated to be 153.8 kΩ. The closest standard value of 154 kΩ is chosen. R3 should be 60.9 kΩ, and 60.4 kΩ is the nearest standard value. Voltage SensorTo measure the voltage which is provided by the solar panel two resistorsR1 and R2 act as as voltage devider when employed in parallel with the solar panel. The voltage across R2 is fed in to a ADC converter and in the voltage follower configuration that is fed to the low pass filter before fedding to the ADCINA0 which is a channel of MPPT controller. If we take R1 1.07 MΩ and R2 165 kΩ respectively than the maximum amount of current from the load is 12. The voltage range is 0-3 Vdc for MPPT controller.

Page 7

Ayushi Vaishy, et al International Journal of Research in Electronics & Communication Engineering [Volume 1, Issue 1, April 2013]

the panel voltage decreasing to 6.5 V and the power supply disabling, the current from C3 goes negative—the capacitor recharges from the panel and stores energy for the next cycle. The current from C3 spikes briefly before the load is enabled, as the power supply turns on when the panel voltage is sufficiently high. Additional input current provided by C3 is needed during start-up.

Fig. 5: Sensing circuit of voltage sensor

Fig: 7: Operation of MPPT circuit within 90% of MPP

Fig: 6: Sensing circuit of Current Sensor To measure current which is provided by the solar panel a resistor is placed in between solar panel and DC-DC converter in series. Current sensors are made by analog devices by which output voltage is fed to the ADC. The voltage across resistor is fed to the ADCINA1. OP-AMP is in voltage follower configuration that pass through a low pass filter before feding to ADCINA1 channel of of MPPT controler. By choosing the value of resistor 51 mΩ maximum voltage drop across the resistor occurs. The voltage range of ADC channel of MPPT controller 0-3 Vdc so the output voltage of AD8215 current sensor which is voltage representation of solar panel’s current should not exceed to 3 Vdc.

Fig: 8: Bulk input capacitor (C3) supplying a circuit operating within 90% of MPP

III. SIMULATION RESULTS & ANALYSIS Figure 3 shows the MPPT circuit in operation. The panel voltage, VIN, remains between 9 V and 6.5 V (VP1 and VP2, respectively). Once VOUT enters regulation, the load enables and draws 250 mA. When the panel’s voltage drops to 6.5 V, VOUT is disabled and thereby disables the load current. The solar panel provides an average of 19 mA at all times. The load has a run time of around 18 ms in Figure 3, meeting the 15-ms requirement. This run time roughly matches the calculations, since the value of C3 increased above the result of those calculations. Figure 4 replaces the output-voltage trace in Figure 3 with the trace for ICap, the current from C3. As VIN decreases, the current leaving the capacitor is positive—the capacitor provides its stored energy to the power supply, which then supplies that energy to the load. Once the load turns off, due to

Webpage: http://ijrece.org

Fig: 9: RS vs Reciprocal of Irradiance

Page 8

Ayushi Vaishy, et al International Journal of Research in Electronics & Communication Engineering [Volume 1, Issue 1, April 2013]

IV. CONCLUSIONS

Fig: 10: Angle of Incidence vs Relative Output Current

Fig: 11: VOC vs ln(irradiance)

When the battery in the off grid system are fully charged and the PV production exceeds to the local load so the excess power has no load to absorb it and MPPT no more operate at its maximumum power point. So MPPT must shift its operating point till production does not matches the demand. A well engineered renewable remote energy system, utilizing the principal of Maximum Power Point Tracking (MPPT) can improve cost effectiveness, has a higher reliability and can improve the quality of life in remote areas. A high-efficient power electronic converter, for converting the output voltage of a solar panel, or wind generator, to the required DC battery bus voltage has been realized. The converter is controlled to track the maximum power point of the input source under varying input and output parameters. Maximum power point tracking for relative small systems is achieved by maximization of the output current in a battery charging regulator, using an optimized hill-climbing, inexpensive microprocessor based algorithm. Through practical field measurements it is shown that a minimum input source saving of between 15 to 25% on 3–5 kWh/day systems are easily be achieved. A total cost saving of at least 10–15% on the capital cost of these systems are achieveable for relative small rating Remote Area Power Supply (RAPS) systems. The advantages at large temperature variations and high power rated systems are much higher. Other advantages include optimal sizing and system monitor and control.

ACKNOWLEDGEMENT The authors are thankful to Mr. Aseem Chauhan (Additional President, RBEF and Chancellor AUR, Jaipur), Maj. General K. K. Ohri (AVSM, Retd.) Pro-VC, Amity University, Lucknow, Prof. S. T. H. Abidi (Director ASET, Lucknow Campus), Brig. U. K. Chopra (Director AIIT & Dy. Director ASET), Prof O. P. Singh (HOD, Electrical & Electronics) and Prof. N. Ram (Dy. Director ASET) for their motivation, kind cooperation, and suggestions.

REFERENCES Fig: 12: VMP vs Illumination (Lux) for Low Irradiance

Fig: 13: PV Output Power at 1000W/m2 and 400W/m2 vs PV Voltage and Current

Webpage: http://ijrece.org

[1] G Hsiao Y.T. e C.H. Chen C.H., “Maximum Power Tracking for Photovoltaic Power System” in Proceedings of IEEE Industry Applications Conference - 37th IAS Annual Meeting, 2002. [2] Sera D., Kerekes T., Teodorescu R., Blaabjerg F., “Improved MPPT Algorithms for Rapidly Changing Environmental Conditions” in the Proceedings of Power Electronics and Motion Control Conference, EPEPEMC’ 06, 2006. [3] T. Noguchi, S. Togashi, R. Nakamoto, “Short-Current Pulse Based Maximum Power Point Tracking Method for Multiple Photovoltaic and Converter Module System”, IEEE Trans. Industrial Electronics, 2002. [4] Ortiz R. E. I., “A MPPT Method based on the Approximation of a PVM Model using Fractional Polynomials” in Proceedings of IEEE Power Electronics Specialists Conference, PESC’2007. [5] D. Casadei; G. Grande e C. Rossi.: “Single-Phase SingleStage based Photovoltaic Generation System Based on a

Page 9

Ayushi Vaishy, et al International Journal of Research in Electronics & Communication Engineering [Volume 1, Issue 1, April 2013]

Ripple Correlation Control Maximum Power Point Tracking”, IEEE Trans. Energy Conversion, 2006. [6] Markvart T.: “Solar Electricity”, John Wiley & Sons, 1994. [7] Lorenzo E., Araujo G.L., Cuevas A., Egidio M.A., Miñano J.C., Ziles R.: “Eletricidad Solar Ingenieria De Los Sistemas Fotovoltaicos”; PROGENSA, 1ª edición, 1994. [8] CRESESBE/CEPEL: “Energia solar Princípios e Aplicações”. Centro de Referência para Energia Solar e Eólica Sergio de Salvo Brito: Sistema Eletrobrás, Brasil, 2000. [9] ALTENER/GREENPRO: “Energia Fotovoltaica:Manual sobre tecnologias projeto e instalação”; União Européia, 2004. [10] C. Cabal; C. Alonso; A. Cid-Pastor; B. Estibals; L. Seguier, R. Leyva, G. Schweitz, J. Alzieu.: “Adaptive digital MPPT control for photovoltaic applications” in Proceedings of IEEE International Symposium on Industrial Electronic, 2007. [11] Energy comparison of MPPT techniques for PV Systems, ROBERTO FARANDA, SONIA LEVA [12] ADVANCED ALGORITHM FOR MPPT CONTROL OF PHOTOVOLTAIC SYSTEMS, C. Liu, B. Wu and R. Cheung [13] On the control of photovoltaic maximum power point tracker via output parameters, D. Shmilovitz [14] An investigation of new control method for MPPT in PV array using DC – DC buck – boost converter, Dimosthenis Peftitsis, Georgios Adamidis and Anastasios Balouktsis

had worked in Electronics for Societal Group, CEERI, Pilani, as a Project Scientist and a Multi – National Company as a Sr. Software Engineer (Bridge Instrumentation Division). He is also associated with the successfully implementation of the Hardware and Software for number of projects undertaken by him and in organizing number of International/National Conferences and Seminars. Ms. Ayushi Vaishy, M.Tech (P) from Amity University Uttar Pradesh, Lucknow in Electronics and Communication Engineering and did B.Tech from Saroj Institute of Technology and Management, Lucknow in Electronics and Communicationn engineering in the year 2010. Her area of intrest in research field is Wireless Communication. She has published research paper by the name “An Innovative Solution to Empower the WiMAX Grid Network for Smart Applications: An Innovation in Intelligent Networks Approach” in a international journal.. Presentely working on project wireless communications with MATLAB and Simulink : IEEE.802.16 (WiMax) Physical layer as the part of her M.Tech final dissertation.

AUTHOR’S BIBLIOGRAPHY Dr. Ajita Pathak PhD (Lucknow University), M.Sc ( Electronics) from Jivaji University Gwalior is a member of academic staff of Department of Electronics & Electrical Engineering (ASET), Amity University Uttar Pradesh, Lucknow, where she is serving in the capacity of Asstt. Professor in the Department of Electronics Engineering (ASET). Mr. Rajinder Tiwari, PhD (P), M.Tech, MIETE is a member of academic staff of Department of Electronics & Electrical Engineering (ASET), Amity University Uttar Pradesh, Lucknow, where he is serving in the capacity of Asstt. Professor in the Department of Electronics Engineering (ASET). He has done M.Tech (I&CE) and M.Sc (Electronics) from NIT, Kurukshetra and University of Jammu, respectively. Presently, he is pursuing Ph.D. (ECE) from Department of Electronics Engineering, Kumaon Engineering College, Dawarahat (Almora) under Uttarakhand Technical University. Mr. Tiwari has given his contribution to the area of Microelectronics (Modeling & Simulation of the Analog CMOS Circuits for ASP Applications), Embedded System Design, Digital System Design and Process Industries Automation and Control System Design (using Graphical Programming Language with dedicated Hardware). He has published several research papers in International/National Journals/Seminar/Conference. He is associated with several technical institutions and bodies as a life member. Before taking the assignment of Amity University, Uttar Pradesh, Lucknow, he

Webpage: http://ijrece.org

Page 10