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Automatic Sun Tracking System (ASTS)
Automatic Sun Tracking System (ASTS)


INTRODUCTION:

In remote areas the sun is a cheap source of electricity because instead of hydraulic generators it uses solar cells to produce electricity. While the output of solar cells depends on the intensity of sunlight and the angle of incidence. It means to get maximum efficiency; the solar panels1 must remain in front of sun during the whole day. But due to rotation of earth those panels canâ„¢t maintain their position always in front of sun. This problem results in decrease of their efficiency. Thus to get a constant output, an automated system is required which should be capable to constantly rotate the solar panel. The Automatic Sun Tracking System (ASTS) was made as a prototype to solve the problem, mentioned above. It is completely automatic and keeps the panel in front of sun until that is visible. The unique feature of this system is that instead of taking the earth as its reference, it takes the sun as a guiding source. Its active sensors constantly monitor the sunlight and rotate the panel towards the direction where the intensity of sunlight is maximum. In case the sun gets invisible e.g. in cloudy weather, then without tracking the sun the ASTS keeps rotating the solar panel in opposite direction to the rotation of earth. But its speed of rotation is same as that of earthâ„¢s rotation2. Due to this property when after some time e.g. half an hour when the sun again gets visible, the solar panel is exactly in front of sun. Moreover the system can manage the errors and also provides the error messages on the LCD display. In manual mode, through the software (GUI) at computer, the solar panel can be rotated at any desired angle.

Fig. 1: Automatic Sun Tracking System”Dishes and PV.





Fig. 2: Automatic Sun Tracking System”Heliostat and Parabolic Trough.


ASTS can be used for Parabolic Trough tracker, Dishes tracker, PV (Photovoltaic generator) tracker, Heliostat, Solar Furnace and so on. Even though the theory of the controller system is similar to all the applications, there are some differences: the precision requirement for dishes tracker is more strict than PV tracker, while the Heliostat and solar furnace need the strictest precision requirement, and more difficult to apply solar sensor to make a closed-loop control system. So, when design these systems, selection of motor type, controller type and tracking mode should be different.











STRUCTURE OF ASTS:

ASTS is a hybrid hardware/software project. Its general structural diagram is shown in figure-3.

The software includes:
¢ VB 6.0 based GUI.
¢ Microsoft Access Database.
¢ Embedded Software (written in C) for microcontroller AT89c52.


The hardware includes:
¢ Solar panel assembly structure containing six functional sensors, stepper motor and solar cells.
¢ System Control Unit containing LCD, Keypad, Error Indicators and Emergency Stop switch.
¢ Complete PCB containing two microcontrollers (89c52). First one is the Master Microcontroller which controls the automatic operation of ASTS. While second one, the Slave Microcontroller serially communicates (RS232) with VB software in computer.



Figure3. General Assembly of ASTS




MOTOR SELECTION:

There are many types of motor can be selected in ASTS design. Currently, several types of motors being used in the area of ASTS around the world are: Step-motor, Servo-motor, AC asynchronous motor, permanent magnetic DC servo motor, permanent magnetic brushless synchronous motor, etc.
Generally speaking, as the gear ratio is high for the transmission system, motor control precision has very small impact to the tracking precision. For example, for a system with the gear ratio of 20000:1, the tracker only covers an angle of 0.314mrad when a one complete circle is finished by the motor. Therefore, all kinds of the motor can satisfy the precision of the tracking system. However the feature of each type of motor is different.

Fig. 4: AC asynchronous motor with encoder
First of all, letâ„¢s take a look at the AC asynchronous motor. To use this kind of motor, we need an encoder to locate the position of the tracker. In our project, we install an encoder at the end of AC motor. The PLC accepts the pulse to locate the tracker, while the transducer is used to adjust the trackerâ„¢s speed. Certainly, we can install an encoder at the end of the transmission to ensure the position of the tracker.
The obvious advantage to use AC asynchronous motor is its price. Even though it can achieve all the needed functions, AC asynchronous motor is too heavy, too large, and too low in efficiency to be installed. Also, for this type of motor, the torque at low speed is very small. In addition to these disadvantages, it needs the work frequency be above 5Hz to function properly. The lowest work frequency in our project is 10Hz. As such, the possibility for us to use AC asynchronous motor in the future is eliminated.


Secondly, letâ„¢s compare the features of DC Servo-Motor and AC servo-motor.

There are two types of DC servo-motor: motor with brush and motor without brush. Motor with brush is low in cost, simple in structure, and high in start torque. Also it has wide range of speed adjustment, is easy to control. Though it needs maintenance from time to time, it is very convenient to repair (replace the brush). However it produces electro-magnetic interfere. Motor without brush is small in size, light in weight, high in output, fast in response, small in inertia, smooth in spinning, stable in output torque, low motor maintenance fee, high in efficiency, low in electro-magnetic radiation, long life, and can be applied in different working environments. However it has more complex control system.
AC servo-motor is also a type of motor without brush. There are two types of AC servo-motor: synchronous AC motor and asynchronous AC motor. Currently, synchronous AC motor is generally used in movement control. It can cover a wide power range, which could be up to a very high power level. Nowadays, with the fast development of semiconductor technology, the shift frequency of power assembly, and the processing speed of micro-computer have been increased significantly. As such, it is possible to put the AC motor controller into a two-axial coordinate system to control the directional current components, in order to achieve the performance similar to the DC motor.

Fourthly, the comparison between AC servo-motor and step motor is done.

AC servo-motor runs smoothly during low speed period; while step-motor is apt to have low-frequency vibration.
In terms of the frequency-torque Characteristics, the output torque of step-motor decreases with the increasing of rotation speed. Furthermore the decrease is steep in high-speed range. AC servo-motor has a comparably stable output torque, when the rotation speed is within the rated rotation speed. It gives the constant output power when the rotation speed is beyond the rated value.
Step-motor doesnâ„¢t have the overload capability; while AC servo-motor posses a satisfactory overload capability. The Panasonic AC servo-system is an example: The maximum
Output torque is three times big of the rated output torque, which can be used to overcome the inertia load during the start period. As the step-motor doesnâ„¢t have the overload capability, a much bigger size of step-motor is needed. Obviously the step-motor will be over-sized during normal operation.
Controllerâ„¢s type of Step-motor is open-loop type. It is easy to have the error of step loss or blockage when the start frequency is high or the load is heavy. Also it is easy to have the error of overshoot when it is stopped. So, to make sure the precision of control be achieved, designer needs to pay more attention to the speed-increase or speed-decrease periods. AC servo-motor system is a closed-loop system. It is possible for the driver-component to sample the signal from the motor encoder to complete a position cycle and speed cycle internally. As such, AC servo-motor system generally will not have the errors of step loss or overshooting, and is more reliable in terms of controlling performance.
Step-motor needs 200 to 400 mil-seconds to accelerate from still to a typical working speed of several hundred rpm. AC servo-motor is better in terms of acceleration performance. For example, Panasonic MSMA 400W needs only a few mil-seconds to accelerate from still to its rated speed of 3000RPM. So it is clear that step-motorâ„¢s performance is not so good. However itâ„¢s cheaper. Started from late 70s and early 80s, with the development of micro-process technology, high-power, high-performance semiconductor technology, and manufacturing technology of permanent magnetic material, the performance price ratio of AC servo-system has been improved significantly. Price of AC servo-system also is gradually deceasing in recent years. AC servo motor is becoming the dominant product.
The conclusion is that all the motors, step-motor, AC asynchronous motor, DC motor with/without brush, AC servo-motor, can be applied in ASTS. Asynchronous AC motor is the cheapest. But it is big in size, and low in technical specification. The step-motor has a simple controlling mode and is also low in price. AC servo-motor has the best performance and wide power range. Its price is also the highest. As for the performance and price for permanent magnetic DC brushless motor, they are both rated between step-motor and AC servo-motor. Its performance is close to servomotor. For the situations that the output torque is not very high (less than 2 NM ), permanent magnetic DC brushless motor is a good option.









SOLAR SENSOR:

Dish type tracking controller and PV tracking controller can be both applied as four- quadrants solar sensor to correct tracking bias. It is known that solar sensor will lose its functionality temporally when itâ„¢s cloudy. In the area of solar thermal generation, solar sensor system usually follows the equation based on the astronomic formula to locate the position of the sun. When a MPU (micro-processor unit) is applied to calculate the sunâ„¢s position, because of its low process speed and low precision, itâ„¢s necessary to include a solar sensor to make a closed loop system. If the tracking system uses a PC or a high-performance DSP as the controller, the bias for the calculated sun position will be within one percent of mrad (milliradian), when the system clock is precisely set (Direct time from GPS is an option). No solar sensor is needed to track the sun, especially when the slope error and the gear-diastema are all small. Exception happens when the motor is a step-motor and the output torque is not enough. The situation can lead to a blockage of the motor (For example, a windy weather), which will fail the tracking system to track the sun precisely. As such, a closed loop solar sensor is recommended in such system. There are many kinds of solar sensor. The four- quadrants sensor was used in our project as shown in Figure 5.



Fig. 5: Four quadrant Sensor
In four quadrant sensor system, the Photovoltaic current will be bigger for the quadrant of bigger solar facular area, which will indicate whether the sunâ„¢s incident ray is parallel with the axial direction of the sensor, then to adjust the angle by the motor. It should be stressed during the solar sensor design that the inside wall of the solar sensor needs to be blacken to avoid misjudgment by the reflection of sunray inside the solar sensor

WORKING OF ASTS:

Basic Principle:

The basic functional blocks of this system are six sensors1, and their operation depends upon the intensity of light falling on solar panel. All sensors (each with different functionality) send their output to microcontroller AT89c52. Then the microcontroller executes predefined task in its software. These sensors are being used with following names and functionality:

Sun Tracking Sensors (STS)
These two sensors are mounted in V shape (figure-6) exactly in the middle of the solar panel (figure-8). The automatic sun tracking is accomplished according to following 3-step diagram.

Figure6. Basic Automatic Sun Tracking Operation
¢ Step-1 shows that when the sun is in front of solar panel, both sensors i.e. STS-1 and STS-2 are getting same amount of light.
¢ In step-2, after some time as the earth rotates the solar panel gets repositioned with respect to sun and STS-1 obtains less amount of light. At this point the LDR i.e. STS-1 sends signal to the microcontroller (figure 3). Then the controller1 rotates motor, resulting the rotation of solar panel towards the sun.
¢ Finally step-3 shows the reorientation of solar panel. The process continues until the end of day.

Figure7. Interface of LDR with Microcontroller
Night Time Fault Detector (NTFD)
In routine work of the system if a general fault2 occurs during nighttime then the next morning it would not work. So at the next sunrise, this sensor detects whether the solar panel is ready for tracking or not. As shown in figure-8, the NTFD is mounted in east of the solar panel so in normal conditions it does not work because it gets lesser intense light (predefined) as compared to the middle sensors i.e. STS-1 and STS-2, but as the fault arises, it starts working.
Day Time Fault Detector (DTFD)
Except some special conditions e.g. cloudy weather etc, the ASTS is supposed to track the sun the whole day. If the panel stops rotation then DTFD detects this type of fault. The mounting strategy of this sensor is same as that of NTFD except that it is mounted in the west.
Night and Cloud Detection
In a cloudy day light intensity is less than a normal day. Similarly during night, light intensity is far less than a cloudy day. So the night and cloud sensors work on this principle to detect the event. To sense a smaller change in light intensity cloud sensor is more sensitive than the Night sensor. In case of Night event, the microcontroller stops all operations of the system and repositions the solar panel towards east to track the sun for next morning.



Figure8. Sensor mounting assembly on solar panel


CONTROL STRATEGY OF ASTS
For a successful operation, the ASTS has two types of control approach:
¢ Automatic Control
¢ Manual Control
Automatic Control
With the help of an efficient algorithm (written in C) only one Master Microcontroller1 is being used to manage the automatic operation of ASTS. This controller has following functions:
¢ Senses all of six sensors.
¢ Drives stepper motor.
¢ Drives LCD.
¢ Controls the warning indicators e.g. buzzer, LED™s etc.
¢ Communicates (by parallel port) with the slave microcontroller. The central driving components of automatic control are only six sensors. Their operation has been explained on the previous page.
Manual Control
As no human made system is so perfect so an unpredictable fault may occur in the any system. That is why a manual control option was also kept in ASTS. While designing this part of control two objectives were kept in mind:
¢ The manual control should work efficiently.
¢ It should be as user friendly as possible. Following two approaches have been used to accomplish the manual control.
¢ Stand Alone System Control Unit
¢ Computer based control unit
Stand Alone System Control Unit
It is a simple user interface, which includes onboard LCD, Keypad, Buzzer and a complete PCB of the system circuit. The LCD (Hitachi HD44780) displays different messages, which can help the user in manually operating the system. While the keypad includes keys of Numeric Digits, Emergency Stop, clock wise rotation and counter clockwise rotation. Using keypad a user can manually rotate the solar panel by entering angle from 0o to 180o. The angle value is limited to only 180 values because after sunrise, the earth almost rotates only 180 degrees and then the sun disappears. The advantage of this unit is that to run the system it does not need computer but its disadvantage is that at a time it controls only one solar panel. In figure-3 this unit shown in yellow color, in middle of solar panel and computer terminal.

Figure 9. Flow Chart showing automatic operation of ASTS

Computer Based Control Unit
This is completely software based control, written in VB 6.0. It incorporates a GUI (figure-10) and a Database, linked with Microsoft Access. Using this software the computer serially communicates (RS232) with the ASTS. The Slave microcontroller (89c51) of the system makes this communication successful. Due to some fault if the solar panel stops rotating, then with the help of this software a user can:
¢ rotate the solar panel manually.
¢ stop all operations of ASTS (in emergency case)
The database of this system can be used to keep records, which can be retrieved even after a long time. While saving the new data, the database automatically takes the date and time from the computer and keeps them saved along with the data, entered by the human being. The advantages of computer-based control include:
¢ Facility of Database.
¢ At a time this software can handle three ASTS systems.
¢ It has an attracting GUI

Figure10. VB based GUI of ASTS







CONCLUSION

Although ASTS is a prototype towards a real system, but still its software and hardware can be used to drive a real and very huge solar panel. A small portable battery can drive its control circuitry. Therefore by just replacing the sensing instrument, its algorithm and control system can be used in RADAR and moveable Dish Antennas





FUTURE ENHANCEMENTS
Many modifications especially in hardware of ASTS are planned:
¢ The computer and System Control Unit would have a wireless communication with the mechanical structure of solar panel.
¢ More sensitive sensors would be used.
¢ To make emergency control better more powerful microcontrollers e.g. PIC 16F877A would be used.
¢ To reprogram the PIC microcontroller a wireless boot loader would be used.

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Solar Tracking system

The Project Entitled “Solar Tracking System” is used to trace the path of the sun and to position the Solar panel according to that .The system uses Microcontroller and a stepper motor for the above purpose . The stepper motor controls the panel direction.

The intensity of the light is sensed by using array of LDR’s the light sensing device the characteristic of LDR is to change its resistance according to the intensity of the light ,for example if the light intensity increases the resistance decreases and vice versa for other condition.

The array sensor value is converted into digital bits, the bits are sent to the microcontroller. Calculations are performed inside the microcontroller according the value given by the sensor.

By manipulating the value the value the controller controls the step angle of the stepper motor. The sensors are placed in such a way the if follows the path of the sun.

The placing of the sensor plays an important role in the system if the path fails the whole system will be disturbed. The motor angle is also sensed such that it must have ability to pull that much heavy load of the solar cell.

The system can be used in places where more current production is needed. The project can be advanced in future according to the user whishes.

STEPPER MOTOR:
It is a type of motor, which is digital i.e., it rotates according to the data given by the microcontroller the need for going for stepper motor is that the accuracy will be while comparing with normal motors.

PLEASE GIVE COMPLETE EXPLANATION ON SOLAR TRACKING SYSTEM.
PANEL CONTROLLED BY MICROCONTROLLER

to get documentation of solar tracking system please make a look on http://studentbank.in/report-solar-track...tem--12514

please inform me about the total cost and where i get this parts...

visit below thread for more details

http://alibabashowroom/automatic-solar-tracking-system.html

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Introduction
This project is about designing and implementing a Solar Tracking system. This system will be used to track and follow the sun during the daytime in order to increase the power which is absorbs by the panels. Since our country is under energy crisis due to shortage of electricity of which main reason is shortage of water and its storage(dams) so we have to find out alternatives of energy sources. The vast and complex system by which energy is produced and used is increasingly at the heart of environment and economic challenges facing the world.
Our country is heavily dependent on highly polluting fossil fuels, particularly coal and oil. Most of which has to be imported. thus reducing the use of fossil fuels is essential for India’s long term economic and long term well being.
Renewable energy is rapidly gaining importance as an energy resource as fossil fuel prices fluctuate. At the educational level, it is therefore critical for engineering and technology students to have an understanding and appreciation of the technologies associated with renewable energy.
One of the most popular renewable energy sources is solar energy. Many researches were conducted to develop some methods to increase the efficiency of Photo Voltaic systems (solar panels). One such method is to employ a solar panel tracking system .This project deals with a microcontroller based solar panel tracking system. Solar tracking enables more energy to be generated because the solar panel is always able to maintain a perpendicular profile to the sun’s rays.
Development of solar panel tracking systems has been ongoing for several years now. As the sun moves across the sky during the day, it is advantageous to have the solar panels track the location of the sun, such that the panels are always perpendicular to the solar energy radiated by the sun. This will tend to maximize the amount of power absorbed by PV systems. It has been estimated that the use of a tracking system, over a fixed system, can increase the power output by 30% - 60%. The increase is significant enough to make tracking a viable preposition despite of the enhancement in system cost. It is possible to align the tracking heliostat normal to sun using electronic control by a micro controller
Design requirements are:
1) During the time that the sun is up, the system must follow the sun’s position in the sky.
2) This must be done with an active control, timed movements are wasteful. It should be totally automatic and simple to operate. The operator interference should be minimal and restricted to only when it is actually required. The major components of this system are as follows.
1) Input photo transducer (LDR).
2) Analog to digital converter.
3) Microcontroller.
4) Tracking software.
5) Output mechanical transducer (stepper motor).
We will complete our discussion
 Phase I-SOLAR TRACKER
 Phase II-MICROCONTROLLER (AT89C51)
 Phase II-STEPPER MOTOR
 Phase III-DRIVER CIRCUIT (ULN2003)
4.OBJECTIVE:
Commercial made solar trackers are a nice addition to any solar panel array. They help increase the time that panels directly face the sun and allow them to produce their maximum power. Unfortunately they can be expensive to buy. We decided to make our own solar tracker to see if we could reduce the cost. We did not want to re-invent the wheel but wanted to make it more affordable. We started out small and came up with the idea of solar tracking using time instead of using a device that would sense where the sun is and move the panels toward it.
4.1Need for this project
Solar energy basically comes in the form of light and heat and has to be converted to electrical energy. The transducer used is a special semiconductor diode called a photovoltaic cell. These cells are usually made of silicon (si), selenium (se), cadmium sulphate (cds) and cadmium telluride (cite). Light falling on the junction induces a potential difference between the two electrodes, electrons are thus mobilized and an external circuit can be driven. More power can be generated out of these cells by increasing the intensity of light falling on them. This can be achieved by keeping the cells perpendicular to the light source. Beside this to make more precisely the use of energy produced from this system we need a such system which would continuously monitor and deliver the information about all the equipment we will install as load.
The Solar Panel.
Solar cells are usually in the form of very thin flat wafers. A number are connected in series or parallel and mounted on flat board to form what is know is Solar panel. Solar panel work by by converting Sun’s energy into electrical energy which is stored in battery. A charge controller between battery and solar panel which protect the battery from over charging. The energy can be taken out of the battery as required(12 or 24 V DC)using a transformer to convert to 220/240 V if required
Design Optimization.
Since we have to track the Sun this means that motor driving the motor continuously but as the motor receiving the power from panel, so the continuous running off the motor will cause the efficiency it suffer a great deal so in order to achieve the maximum efficiency. We have to design our tracker in such a way that the motor consume minimum power so we had to different ways to handle situation.
First was by using the stepper motor in which timing algorithm is implemented.
Second was by using DC motor in which direction is controlled by LDR sensors.
We select the second method because of its efficiency, in terms of not consuming the power continuously even in cloudy weather it is efficient also it don’t need a long and complex calculation

to get information about the topic Industrial control Using Cellphone" and "solar tracking system" full report,ppt and related topic please refer the page link bellow

http://studentbank.in/report-time-operat...tem?page=2

http://studentbank.in/report-automatic-s...sts?page=3

http://studentbank.in/report-time-operat...tem?page=1

http://studentbank.in/report-automatic-s...sts?page=1

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plese send me the code(program) of solar tracking system using 8051mc to my email.id ramesh.appana143[at]gmail.com

To get full information or details of Automatic Sun Tracking System please have a look on the pages



http://studentbank.in/report-automatic-s...ystem-asts

http://studentbank.in/report-automatic-solar-tracker

http://studentbank.in/report-automatic-s...ker?page=2




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