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ABSTRACT
The present thesis, Microcontroller Based Power Theft Identifier, introduces the concept of preventing the illegal usage of the electrical power. Here, the radio communication principles are employed and also the technology of Microcontrollers is utilized to find out the user trying for pilferage of power i.e., by displaying the respective consumer meter number and address.
For the complete operation, the system can be sub-divided into two major sections, one is the transmitting section and the other is the receiving section. The transmitting section has to be incorporated at the consumer’s end and the receiver section has to be placed at the electrical sub-station.
In the transmitting section, two types of automatic power theft detection schemes are provided. In the first scheme, within the meter (inside the bottom cover), an electro-optical sensor is placed and it is configured to feed trigger signal for the timer circuit. Whenever light falls on it (when user tries to open the bottom cover), the output of the timer circuit energizes a relay which provides supply for modulating input section which differs from user to user. An F.M Transmitter is designed with a carrier of 100 MHz. Here, the modulating input is superimposed over the carrier and is transmitted. In the second scheme, a transmitter is connected to the bottom cover. If the user touches this bottom cover, due to electro-static charge associated with human body, the transistor gets turned on and energizes the relay, which provides supply for modulating input section.
In the receiving section, the signal received is demodulated, amplified and digitized (using ADC) and is fed to Microcontroller (8051). Microcontroller identifies the frequency and its associated user. Then it energizes an alarm and displays the address of the user.
INTRODUCTION
The proposed project work aims on the design and development of energy theft prevention aspect. Thereby, energy pilferage can be reduced to a considerable extent. This project envisages the development of energy theft identification. Hence this project work is titled as “MICROCONTROLLER BASED POWER THEFT IDENTIFIER”.
Now-a-days the energy consumption and energy distribution has become a big subject for discussion because of huge energy pilferage. Hence the need has come to think in this line and a solution has to be emerged out. Thus this project work has been taken up which serves the purpose of energy monitoring so that the energy thief can be easily caught, thereby huge penalties can be imposed on energy thieves. By detecting the energy theft cases, people or electric consumers will become alert and thereby the energy theft can also be prevented.
This project work is basically related to Radio communication. As we know the modern communication plays a dominant role in the communication revolution, the proposed project work is aimed to use radio communication between energy consumer and centralized electric sub-station, where the energy theft monitoring is performed. Hence, this project work is divided into two units i.e. (1) energy theft detection at energy consumer’s place, (2) Centralized radio receiver, where the power theft information is received, decoded and monitored using Microcontroller.
The energy theft detection consists of energy theft detector, suitable tone generator and F.M Radio Transmitter. The frequency of tone generator differs from one energy consumer to the other. The frequencies are allocated according to the energy consumer’s identification code.
In this project work, for the demonstration purpose two analog energy meters are considered, one is equipped with light sensing circuit and the other one is equipped with touch sensitive circuit. Whenever, one tries for energy theft by opening the top cover of the energy meter, the light falls on the LDR which is arranged inside the meter, this in turn enables the relay which thereby enables the tone generator. The tone generator generates the tone signal as a modulating signal to the built in 100MHz F.M.Radio Transmitter. Thereby the F.M.Radio Transmitter transmits 100MHz Carrier signal super imposed with tone signal in the frequency modulation mode.
The centralized energy monitoring system receives the F.M signal with the help of F.M.Radio receiver. The received signal is demodulated and amplified with the help of transformer coupled amplifier. The detection is performed with the help of a versatile IC TEA 5591A. The advantage of this type of radio receiver is, it provides all the major functions required for modern FM designs of receivers.
The received audio tone signal is amplified using signal amplifier. The amplified tone signal is converted into the voltage proportional (using frequency to voltage converter) to the signal frequency. This conversion is performed by using phase locked loop (PLL) technique. The amplitude output of the PLL is proportional to the frequency of the tone signal, which is proportional to the electric consumer’s identity code. This signal amplitude is fed to the analog to digital converter circuit for converting the analog information into digital pulses.
For sensing the energy theft, in addition to the LDR arrangement, another technique is also incorporated in this project i.e. Touch Sensitive Circuit. If energy consumer touches the energy meter, the touch sensitive circuit actuates which energizes the relay and remaining is same as described above.
In the recent survey conducted by the state electricity departments, shows that the electric generation and consumption records are not tallying due to lot of energy pilferage. As there is no method to detect energy pilferage, the genuine energy consumers are charged with huge charges, thereby it is becoming a burden to them. Hence to avoid and to detect the energy theft, it is decided to put effort in this direction and our project is taken up to detect energy theft consumer and pass it on to the centralized energy monitoring station.
BLOCK DIAGRAM AND ITS BRIEF DESCRIPTION
The project work “MICROCONTROLLER BASED POWER THEFT IDENTIFIER” is categorized into to two sections viz. Energy theft detection unit (Transmitter Section) located at consumer’s place and centralized detection and display unit using Microcontroller (Receiver Section) located at electrical sub-station, where the anti- power theft squad of the State Electricity Department monitor system continuously.
TRANSMITTER SECTION:
The energy theft identification unit located at energy consumer’s location consists of LDR configured in mono stable mode using IC 555 timer. The timer consists of two comparators, which are enabled at 1/3vcc and 2/3vcc. Thus as long as the light does not fall on the LDR, the output of the timer is at low state. Whenever the energy meter is opened or tampered, the light falls on LDR. This makes the resistance of the LDR to fall to a low value of less than 500ohms from high value of more than 100Kohms. This in turn changes the threshold level of the timer and the output is made high. This will enable the relay driving transistor and in turn energizes the relay. This relay in turn provides supply to the tone generator circuit i.e., the modulating input block.
The audio tone generator is configured with 555 timer IC in astable mode. The frequency of the timer is selected with R-C of circuit. The audio tone generator generates tone frequency corresponding to the electric consumer involved in energy theft. In this project, for demonstration purpose, two theft detectors are provided. One is light sensing device and the other one is touch sensitive device, which generates 2 KHz and 3 KHz audio frequencies respectively. Output of both the tone generators are fed to the F.M Radio transmitter operating at 100MHz.
RECEIVER SECTION:
The circuit at centralized sub-station consists of F.M Radio receiver built with IC 5591A. In this case, it is used as a F.M detector and limiter with minimum of external components. This IC includes cascaded stages of IF limiter and balanced product detector with a very low harmonic distortion and high IF voltage gain. The detected signal of the FM receiver is fed to the audio amplifier, which amplifies the signal. The amplified signal is fed to frequency to voltage converter that uses phase locked loop IC CD 4046 and multiplexer CD 4053. This frequency to voltage converter circuit converts the input frequency into output D.C voltage. The phase locked loop IC contains a stable, highly linear voltage controlled oscillator for low distortion F.M demodulation, and double balanced phased detection. The characteristics of the closed loop system, bandwidth, response speed, capture and pull in range may be adjusted over a wide range with external resistors and capacitors. Thereby the D.C output voltage, which is proportional to the tone frequency, is fed to the analog to digital converter block.
Here, ADC0809 IC (8-bit A/D converter) is used to convert the output of frequency to voltage converter, which is an analog voltage, into an output binary word that can be used by a Microcontroller.
For monitoring and displaying of meter tampering (consumer number and address can be displayed on the LCD display which is connected at the output of Microcontroller) assembly language is used
OBSERVATIONS
ADVANTAGES:
The system consumes very little power for its operation.
System operation is independent of time (24 hours functioning).
Automatic user identification.
LIMITATIONS:
Since the techniques employed in this module are based on simple electronics, the chances of making the system inoperative are more. But, if a Microcontroller chip is used for feeding the modulating input, we can make the system more efficient.
Wide range of frequencies is required to facilitate large number of users. To overcome this, carrier levels can be changed from region to region.
Presently, it requires a power supply (230 V) for the operation, but a small battery with automatic charging facility can be provided in real time.
APPLICATIONS:
The system can be incorporated for almost all types of users.
The concept is well suited especially for villages and interior areas.
POSSIBLE FUTURE IMPROVEMENTS:
In addition to the power theft information, the same transmitter can be used for transmitting the data indicating the used energy (number of units). If this is done, then there will be no requirement of data collection (i.e. a lot of man power can be saved).
Two way communication can be designed, so that a signal (from sub-station) can be transmitted which disconnects the main line from meter if the user did not pay the bill in time or if the user is trying for power theft.
CONCLUSION
In this present project, the scheme for detecting the power theft is based on the concepts of electro-optical sensors and the electro-static charge associated with the human body. Also, the theme was successfully verified and proved. But, when the system has to be employed in real time, a lot of sophisticated schemes can combinely be employed so that the chances for power theft can almost be eliminated. As it is a prototype simulation, the distance between transmitter and receiver is restricted to 10 meters. The range between the transmitter and receiver can be increased based on the requirements to the desired extent with the usage of pre-amplifier stages and proper antennas. The concept can be applied to places where proper measure and preventive steps cannot be easily taken, especially for villages and interiors areas. The present system has to undergo lot of modifications and sufficient R & D has to be done to make the system more compact, handy and economical. With the implementation of this kind of systems in the real time, the need for regular vigilance can be avoided and power can be supplied at the economical rates, thereby improving the economy of the country
