Design and Development of Data Logger for Standalone SPV Systems

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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal, Volume 5, Issue 5, May 2015)

162

Design and Development of Data Logger for Standalone

SPV Systems

Girishkumar Malagond

1

, Gagan Bagewadi

2

, L Pooja

3

, Basanagouda F. Ronad

4

, Suresh H. Jangamshetti

5

1 ,2,3_{Undergraduate Students,}4_{Assistant Professor, Member IEEE,}5_{Professor, Senior Member IEEE, Department of}

Electrical and Electronics Engineering, Basaveshwar Engineering College (Autonomous), Bagalkot-587103, Karnataka, India.

Abstract- Solar energy is being utilized for electricity generation at large scale. Electricity generations in such units are monitored through SCADA systems. However, facilities to monitor the performance details of smaller sized systems or individual panels are not available. This necessitates need for data logger for small scale standalone SPV systems. This paper presents design and development of data logger for standalone SPV system. The proposed circuit includes ACS712 current sensor, Voltage divider, LM35 temperature sensor, LDR and PIC microcontroller. Real time values of current, voltage and irradiation are sensed and processed in microcontroller. LDR is calibrated to measure the solar radiation and used for assessing the efficiency of the panel. The measured data is transmitted through GSM to smart phone. Data is then stored in SD card using an android application. Proposed model is validated by conducting experiments on 75 W SPV panel. Thus it is concluded that proposed data logger will be an economic and effective way of assessing the performance of standalone SPV systems.

Keywords- SCADA (Supervisory control and data acquisition), GSM (Global System for Mobile Communications), SD card (secure digital memory card).

I. INTRODUCTION

Non-conventional energy sources are continuously produced by natural processes and forces occurring in nature. In that solar energy is most promising option. Sun produces enormous amount of energy, which reaches earth in the form of solar radiation. Solar energy is being utilized for electricity generation at large scale. Monitoring the generation needs data logging unit. Data Logger is an electronic device that continuously measures the parameters such as temperature, pressure, humidity, radiation and stores measured data in storage device. They are usually portable, battery-operated devices with internal storage and sensors to measure physical quantities [3].

Approximately 20 MW of SPV power generating units are installed in Karnataka. Performance of these units is monitored through SCADA system.

Nearly 5 kW of SPV panels are installed in Basaveahwar Engineering College campus Bagalkot. However, performance details of installed panels are not available. This has lead for improper utilization of the generated electricity. This indicates the need for development of data logger for smaller SPV systems. In this regard, efforts have been made for the smaller installed capacity.

K. N. Akposionu, proposed design and fabrication of low cost data logger for solar energy parameters. Data logger was designed for measurements of two parameters i.e temperature and voltage. Low cost data logger is a single board computer based embedded platform. Temperature and SPV voltage variations were logged successfully. Logged data is then transferred to the personal computer for further analysis [1].

Pratik Painjane, presented design of solar insolation level detector and data logger. In this system measurement of incident power per unit area and duration of maximum sunshine was carried successfully. The system comprises of photodiode, RTC (Real Time Clock), Servo Motors, Microcontroller and LCD. Photodiode gives output proportional to sun intensity. This output is then processed and converted into the unit of insolation level as watt per meter square [2].

In similar, the literatures were concentrated on the individual parameters only. Further, complete set of parameters are to be measured in a single logger. To satisfy this, in proposed circuit measurement of Current, Voltage, Temperature, Radiation and calculation of efficiency are carried out.

II. METHODOLOGY

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International Journal of Emerging Technology and Advanced Engineering

163 Microcontroller has inbuilt ADC, which converts analog signal to digital value. These values are displayed on the LCD and simultaneously sent to smart phone through GSM. Received data is stored in SD card using android application.

Fig.1. Block diagram of praposed work

Fig.2. presents circuit construction of said data logger. The topology of the circuit indicates the positioning of the sensors.

Fig.2. Cicuit cunctruction

A. Current Sensor

The ACS712 current sensor is based on the principle of Hall-effect. According to this principle, when a current carrying conductor is placed into a magnetic field, voltage is generated across its edges perpendicular to the directions of both the current and the magnetic field. A thin sheet of semiconductor material is carrying a current and is placed into a magnetic field which is perpendicular to the direction of current flow. Due to presence of Lorentz force, the distribution of current is no more uniform across the Hall element and therefore a potential difference is created across its edges perpendicular to the directions of both the current and the field.

This voltage is known as Hall voltage and its typical value is in the order of few micro volts. The Hall voltage is directly proportional to the magnitudes of current [5]. This is presented by (1) and principle of Hall effect is presented in Fig.3.

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Sensitivit

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Current

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Fig.3. Principal of Hall Effect [9]

The output of the device has positive slope when an increasing current flows through the copper conduction path. The ACS712 device comes in three variants, providing current range of ±5A (ACS712-05B), ±20A (20B), and ±30A (30A). The ACS712-05B can measure current up to ±5A and provides output sensitivity of 185mV/A, it means for every 1A increase in the current through conduction terminals in positive direction, output voltage also rises by 185 mV. The sensitivities of 20A and 30A versions are 100 mV/A and 66 mV/A, respectively [5].

B. Voltage divider

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International Journal of Emerging Technology and Advanced Engineering

164 Fig.4. Voltage Divider



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V

R

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Let R2=1 k Ω, Vout=5 V, Vin=21 V.

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C. Temperature Sensor

National semiconductor’s LM 35 IC is used for sensing the temperature. It is an integrated circuit sensor that can be used to measure temperature with an electrical output proportional to the temperature (in °C). The temperature can be measured more accurately. The output voltage of LM 35 is converted to temperature in °C is presented in (3) [6].

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Pin configuration of IC LM35 is shown in Fig.5.

Fig.5. Pin configuration of LM35

D. LDR

Light Dependent Resistor or photo resistor is a device whose resistivity is a function of the incident light radiation. Hence, they are light sensitive devices. They are also called as photo conductors.

They are made of semiconductor materials having high resistance. A light dependent resistor works on the principle of photo conductivity. It is an optical phenomenon in which the materials resistivity reduces when light is absorbed by the material. When light falls on the device, the electrons in the valence band of the semiconductor material are excited to the conduction band. The result of this process is that current starts flowing and hence resistance of the device has decreased. Then the voltage is measured across the LDR intern that voltage is directly proportion to the intensity of the light [7].

Calibration of LDR for the proposed work:

5 volts supply is given to the LDR as input, and output of LDR is observed between (0-5) volts. As sunlight falls on the device, resistance decreases with increase in the intensity of light. Hence the output voltage increases. Output voltage calibrated with standard pyranometer data which is installed in BEC, Energy Park. This method is cost effective as compared to conventional radiation sensors. Experimental setup for LDR calibration is shown in Fig.6.

Fig.6. Connection of LDR

E. LCD and PIC Controller

LCD (Liquid Crystal Display) screen is an electronic display module. LCDs are economical, easily programmable. A 16x2 LCD means it can display 16 characters per line and there are 2 such lines. In this LCD each character is displayed in 5x7 pixel matrix. This LCD has two registers, namely, Command and Data. The command register stores the command instructions given to the LCD. A command is an instruction given to LCD to carry out a predefined task like initializing it, clearing its screen, setting the cursor position, controlling display etc. The data register stores the data to be displayed on the LCD. The data is the ASCII value of the character to be displayed on the LCD. It is capable to display any character with ASCII values ranging from 0 to 255 [8].

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International Journal of Emerging Technology and Advanced Engineering

165 PIC18F4520 is 40 pin IC it has 32KB of program memory, 1536 Bytes of RAM, it has 13 channel 10-bit inbuilt ADC and operating voltage range of about 2 to 5.5 volts.

It has Four Crystal modes, up to 40 MHz. Before developing hardware model the circuit is implemented in Proteus and simulated as shown in Fig.7.

Fig.7.Circuit Connection in proteus software

F. Working Principle

ACS712 is connected in series with load and voltage divider across the load for measurement of current and voltage respectively. Output of these devices will be voltage in the range 0-5 volts. This output voltage is given to PIC controller. PIC controller has inbuilt ADC which converts Analog value to Digital Value, these values are displayed in LCD and simultaneously measured value is sent to smart phone by using GSM with a time interval of 1 min. Once message received from GSM, android application stores the values in the SD card as a text file. Complete methodology is described by flowchart, in Fig.8.

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International Journal of Emerging Technology and Advanced Engineering

166 III. RESULTS

The proposed circuit model was tested for validation in Renewable Energy and SCADA Lab, Dept of Electrical and Electronics Engg, Basaveshwar Engineering College (Autonomous), Bagalkot. 10 W and 75 W SPV panels were connected to bulb loads of 10 W and 7 W and different parameters were successfully logged and displayed in LCD. Further, data was sent through GSM to SD card. Fig.9 and Fig.10 shows the output demonstration of data logger.

Fig.9. Screenshot of mobile Android Application

Fig.10. LCD Output

The LCD display and screenshot of mobile display showing android application indicates the successful implementation.

IV. CONCLUSION

Design and Development of data logger for standalone SPV systems is presented in the paper. Experiments were conducted to validate sensors used for current, voltage, radiation and temperature measurement. A new technique for assessing the solar radiation is demonstrated and successfully implemented in the proposed circuit. Complete model was designed and simulated in Proteus software. Further, proposed model was tested for performance study of 75 watt SPV panel. Data obtained are stored in the SD card along with date and time as a text file. Thus it is concluded that, proposed data logger is an economic and effective solution for performance analysis of small scale standalone SPV systems.

REFERENCES

[1] K. N. Akposionu, “Design and Fabrication of A Low-Cost Data Logger for Solar Energy Parameters”, Journal of Energy Technologies and Policy, ISSN 2224-3232 (Paper) Vol.2, No.6, 2012.

[2] Pratik Painjan, Rahul Nangare, Anupsing Pardeshu, “Design of Solar Insolation Level Detector and Data Logger”, International Journal of Current Engineering and Technology E-ISSN 2277-4106, P-ISSN 2347-5161.

[3] Chetan Singh Solanki, “Solar Photovoltaic Technology and Systems”, A Manual for Technicians, Trainers and Engineers: 2nd

Edition, PHI Learning Pvt, 2014.

[4] Jacob Millman, Christos C. Halkias, “Electronic Devices and Circuits”, TATA McGraw Hill Edition.

[5] http://embedded-lab.com/blog/?p=4469

[6] http://www.facstaff.bucknell.edu/mastascu/elessonsHTML/Sensors/ TempLM35.html

[7] http://www.electrical4u.com/light-dependent-resistor-ldr-working-principle-of-ldr/

[8] http://www.engineersgarage.com/electronic-components/16x2-lcd-module-datasheet#