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1460266540-fullreportonELECTRONICPREPAIDBILLINGSYSTEM.docx (Size: 1.08 MB / Downloads: 4)
Introduction
The present practice of electricity billing is manual method only. With this, the total billing is a time consuming process and it requires more manpower. The collection of billing is late procedure and so many consumers may not pay in time. Disconnecting of unpaid connections is also manual. Due to all these drawbacks we cannot have proper auditing. Lack of awareness on power consumption and also the present energy meters displays only units, so the user cannot plan his usage of power. To avoid all these problems, we are introducing this system.
The short message system (SMS) of a standard mobile phone can be used for much more than just exchanging cryptic message. The SMS service provides by the service providers are comparatively low cost. Hence the system is highly efficient and low cost. The Short Message Service allows text messages to be sent and received to and from mobile telephones. The text can comprise words or numbers or an alphanumeric combination. Because Simple person - to - person messaging is such an important component of total SMS traffic volumes, anything that simplifies message generation as well as extended utility of the SMS being sent is an important enabler of Short Message Service. Such extended utility of SMS fulfills certain important requirements.
Now a day’s no one is using this type of system in India, but in future in order to save the energy and get systems automated we should use this type of intelligent system. Wastage of power is inevitable in large industries. This is because the existing system.
line automatically with an alarm prior to that. The consumption data, card status and line status are transmitted to substation for auditing. With this system, we can determine the difference between the actual powers consumed and sold power easily. With this we can easily identify the tampered areas and we can avoid power thefting. In this project, the present billing system was eliminated completely and a new system namely prepaid billing system was introduced for embedded applications which overcomes the drawbacks in present billing system. If this system comes in our day to day life it will be useful for both the Government and the public. A Prepaid Energy Meter is used to collect the electricity bills from the consumers according to their consumption. The prepaid meter is not only limited to automate the meter reading(AMR) but also attributed with prepaid recharging ability and information of consumed data can be exchange between the grid and consumer .The detail of consumed data which is send by the prepaid energy meter can be stored in the grid computer for future verification. To automate the system of billing of energy is the main theme of this project. The front end of this project is user friendly and the employees can work on with minimum knowledge of computers.
. DESIGN PRINCIPLE
The Prepaid Energy meter with Mobile Based Recharging System is designed by using a 8 bit microcontroller. The Microcontroller receives the pulse by interfacing optical pickups from a traditional electromagnetic energy meter. The Prepaid Energy meter with Mobile Based Recharging System works with the principle as follows….
2.1 Pulse Counting
The electronic energy meter is interfaced to the microcontroller through opto-isolator. The energy meter receives its Input from two number of CT's, one is connected to the phase and the other one is connected to the neutral. A V.T. through bridge rectifier is used to provide (+5V/+12V) to the microcontroller & other component for their use. So the processor reads V from V.T., I(depends on Power Factor) from C.T. and their product is seen on the digital screen of the Meter. The energy meter internal circuit working with a low voltage (+5v) which is not isolated.
There are four LED on Energy Meter.
1. Phase (Mains ON)
2. Earth
3. Rev (Revolution)
4. Cal (Pulse counter)
The Microcontroller receives the pulse by interfacing optical pickups from a traditional electromagnetic energy meter. Since the energy meter is working with a non-isolated supply, we are using an isolation circuit to get a pulse from the energy meter called Opto-isolator circuit using a mct2e IC.
2.2 Overload Detection
This over current relay will work for A.C. Voltage and current. The sampling method in this design is based on the transformer principal. The load current passes through the primary of the transformer; the drop across the transformer is very negligible as the resistance of primary circuit is very less. But the flux developed due to primary current will induce an alternating voltage in secondary winding. That voltage is very small and also very much weak by strength. The signal developed at the secondary is very much linear with input current until the core saturation takes place. The transformer o/p is a proportional signal with respect to line current. As this signal is very weak we use a buffer amplifier which is a unity gain amplifier, which doesn’t change the value of the signal, but it increases the current or driving strength. Now this signal is sufficiently strong to be feed in to an amplifier which is an inverting amplifier which provide a fixed gain to the signal, the output of the amplifier is an alternating signal, which is filter rectified with a half weave rectifier and smoothen with a filter circuit. The rectifier output signal has to be companied with the set values. The existing comparator circuit has four comparator. So four reference values can be set with the help of presets. The comparator is always in line with the signal and indicates the level of current in the load line. With the help of a miniature rotary switch one of the comparator output will be chosen. The setting of that comparator reference voltage will be the indicative of tripping current.
2.3 Mobile Phone based recharging
In this project the Prepaid Energy meter can be charged from a remote by using a mobile. Once the user feel to recharge the prepaid energy meter, he can transfer the amount to the service provider bank account and the service provider will make a call to the system and log in to that and charge it by entering digits from its key pad. The recharging can be done from any mobile set but the system access code must be put in to the system to log into the energy meter. This type of systems are now days getting popular. Many popular and well known companies make products and sale in the market.
The energy meter sends a pulse to the microcontroller indicating a unit is consumed. The controller calculate the number of pulse and display the balance units left in the system. When the system do not have any balance it trips the main relay to disconnect the supply from load. When the user transfer money to the service provider’s account then the service provider rings up to the mobile connected to the system and sends a code through the DTMF coding system, the controller programmed in the system reads that and recharge the system to start again. The system is installed with an embedded operating system to provide a user friendly environment with the help of alphanumeric LCD.
DISCRIPTION OF BLOCK DIAGRAM
Discription of block diagram as given follows….
3.2.1 POWER SUPPLY
A power supply is an electronic device that supplies electric energy to an electrical load. The primary function of a power supply is to convert one form of electrical energy to another and, as a result, power supplies are sometimes referred to as electric power converters. Some power supplies are discrete, stand-alone devices, whereas others are built into larger devices along with their loads.
3.2.2 GSM MODULE
A GSM module assembles a GSM/GPRS modem with standard communication interfaces like RS-232(serial port), USB etc. So that it can be easily interfaced with a computer or a microprocessor/microcontroller based system. The power supply circuit is also built in the module that can be activated by using a suitable adaptor.
3.2.3 MAX 232
The MAX232 is an IC, first created in 1987 by Maxim Integrated Products, that converts signals from an RS-232 serial port to signals suitable for use in TTL compatible digital logic circuits. The MAX232 is a dual driver/receiver and typically converts the RX, TX, CTS and RTS signals.
3.2.4 MICRO CONTROLLER
A microcontroller is a small computer on a single integrated circuit containing a processor core, memory, and programmable input/output peripherals. Program memory in the form of NOR or OTP ROM is also often included on chip, as well as a typically small amount of RAM. Microcontrollers are designed for embedded applications, in contrast to the microprocessors used in personal computers or other general purpose applications.
3.2.5 LCD DISPLAY
A liquid-crystal display (LCD) is a flat panel display, electronic visual display, or video display that uses the light modulating properties of liquid crystals. Liquid crystals do not emit light directly.
3.2.6 ENERGY METER
An electricity meter, electric meter, or energy meter is a device that measures the amount of electric energy consumed by a residence, business, or an electrically powered device.
3.2.7 RELAY
A relay is an electrically operated switch. Many relays use an electromagnet to mechanically operate a switch, but other operating principles are also used, such as solid-state relays. Relays are used where it is necessary to control a circuit by a low power signal (with complete electrical isolation between control and controlled circuits), or where several circuits must be controlled by one signal.
A type of relay that can handle the high power required to directly control an electric motor or other loads is called a contactor. Solid-state relays control power circuits with no moving parts, instead using a semiconductor device to perform switching.
DISCRIPTION OF CIRCUIT DIAGRAM
a. VOLTAGE SENSOR
In this scheme, energy meter IC (AD7751) is biased around the neutral wire and a resistor divider is used to provide a voltage signal that is proportional to the line voltage. A voltage divider is made in combination of 1 MΩ resistor and 1 kΩ resistor. The output voltage across the 1 kΩ resistor is applied to the voltage channel of the energy meter IC. b. CURRENT SENSOR
The voltage outputs from a calibrated resistor of 3.335 mΩ connected with the neutral wire is applied to the current channel of the energy meter IC. Current channel has a programmable gain amplifier with gains of 1, 2, 8, or 16. The maximum peak differential voltage is ±660 mV divided by the gain selection.
c. ENERGY METER IC
Energy meter IC has two ADCs that digitizes the voltage and current signals from the supply main. These ADCs are 16-bit second order sigma-delta converters with an over sampling rate of 900 kHz. A high-pass filter in the current channel removes any dc component from the current signal. The real-power calculation is derived from the instantaneous power signal. The instantaneous power signal is generated by a direct multiplication of the current and voltage signals. In order to extract the real-power component, the instantaneous power signal is low-pass filtered .The low frequency output of the energy meter IC is generated by accumulating this real-power information .The output frequency is therefore proportional to the average real-power. This average real-power information can in turn be accumulated by a counter to generate real-energy information.
d. MICROCONTROLLER
Microcontroller is a programmable device which contains a microprocessor, memory, input-output ports etc, which can be compared with the microcomputer. Microcontroller is a single chip computer. As microcontroller is a low cost programmable device. It is used in the automatic control application. Now the pulses produced at the pin CF is directly applied to the counter pin of the microcontroller. The microcontroller counts the pulses that appear at pin 1 of Microcontroller within every 20 seconds. The number of pulses per second appeared at pin 22 of Energy Meter IC is directly proportional to the instantaneous real power information for a particular load. Information such as power, energy, and maximum demand are stored at the EEPROM of the Microcontroller .
e.SMART CARD AND Its COMMUNICATION WITH SERVER TERMINAL AND ENERGY METERING SYSTEM
A microcontroller (ATtiny13) is used as a smart card in which the numbers of units to be recharged are loaded by interfacing with the USB port and the user operated PC of server terminal. The ATtiny13 will send the information contained on it to the microcontroller ,when the DIP switch connected with the two microcontrollers is switched on. Then the information of microcontroller (ATtiny13) will be transferred to the microcontroller (ATmega32) and stored in the EEPROM of the microcontroller while erasing the content of the ATtiny13.The number of recharged units are contained in the EEPROM of the microcontroller and will be gradually decreased with the increment of the energy consumption by the load. The updated value after the execution of the every step will be stored in the EEPROM of the microcontroller. Now the consumers have to recharge the smart card from server terminal for further use of energy after finishing the previously recharged units.
f. RELAY CONTROL UNIT
Five relays each of rating 10A are used. One relay is only used to provide the coil current. When this relay will conduct then it energizes the rest of the relays and consequently the load current will flow through the four relays only which acts as one relay of rating 40A. When the number of units stored in the EEPROM reaches zero, the microcontroller (ATmegs32) initiates a pulse to the base of the transistor. Then the transistor will be switched on which initiates the operation of the relay and consequently the relay will be off. When the credit card is again recharged, the ATmega32 will send a pulse for which the relay establishes a connection between the load and the supply mains. g. DISPLAY UNIT
The liquid crystal display controller displays alphanumeric characters and symbols. It can be configured to drive a dot-matrix liquid crystal display under the control of microcontroller. In this paper, LCD is mainly used to display energy consumption of the load, the number of units recharged by the consumer, rest units, maximum demand of consumer. h. POWER SUPPLY UNIT
Every electronic circuit needs appropriate power supply for its operation. Basically Microcontrollers, Energy Meter ICs, Liquid crystal display and relays operate on ±5 volts supply. For this reason, we have used a ±5volt power supply. We have taken into consideration the small energy consumed by the power supply itself that will be paid by the consumers.
4.3.WORKING The figure 4.1 shows the circuit diagram of our project. The impulse detector circuit detects the blinking of the Energy meter with the help of a photo detector. When the energy meter’s led blinks the photo detector detects it and the impulse detector circuit trigger a interrupt pin of the microcontroller , The transmitter and the receiver pin of the GSM is connected to the receiver and transmitter pin of the microcontroller that will be used to have transmission of control messages between the two . The programming is made as so that it counts the number of pulses that is detected by the sensor and stores the count in the controller. The controlling commands of the GSM is also sent from the controller like the AT+CMGF=1 and the AT+CNMI=1,2,0,0,0 . This two commands will enable the GSM to start and allow the text mode. The LCD is used to display the count and the impulse of the energy meter. It is connected to port 0 and port 1 of the microcontroller. The register, read and write is connected to the port 1 and controls the reading and writing in the LCD. The power supply to the system is provided using a 12V/750mA transformer and is bride rectifier and finally reduced to 5V using a voltage regulator.
MICROCONTROLLER
8051 is the name of a big family of microcontrollers. The device which we used in our project was the 'AT89S52' which is a typical 8051 microcontroller manufactured by Atmel .The block diagram provided by Atmel in their datasheet that showed the architecture of 89S52 device seemed a bit complicated. A simpler architecture can be represented below. The 89S52 has 4 different ports, each one having 8 Input/output lines providing a total of 32 I/O lines. Those ports can be used to output DATA and orders do other devices, or to read the state of a sensor, or a switch. Most of the ports of the 89S52 have 'dual function' meaning that they can be used for two different functions.The first one is to perform input/output operations and the second one is used to implement special features of the microcontroller like counting external pulses, interrupting the execution of the program according to external events, performing serial data transfer or connecting the chip to a computer to update the software. Each port has 8 pins, and will be treated from the software point of view as an 8-bit variable called 'register', each bit being connected to a different Input/Output pin.
There are two different memory types: RAM and EEPROM. Shortly, RAM is used to store variable during program execution, while the EEPROM memory is used to store the program itself, that's why it is often referred to as the 'program memory'. It is clear that the CPU (Central Processing Unit) is the heart of the micro controllers. It is the CPU that will Read the program from the FLASH memory and Execute it by interacting with the different peripherals.
5.2. LEVEL SHIFT IC
A voltage regulator is designed to automatically maintain a constant voltage level. A voltage regulator may be a simple "feed-forward" design or may include negative feedback control loops. It may use an electromechanical mechanism, or electronic components. Depending on the design, it may be used to regulate one or more AC or DC voltages.
Electronic voltage regulators are found in devices such as computer power supplies where they stabilize the DC voltages used by the processor and other elements. In automobile alternators and central power station generator plants, voltage regulators control the output of the plant. In an electric power distribution system, voltage regulators may be installed at a substation or along distribution lines so that all customers receive steady voltage independent of how much power is drawn from the line.
LCD
A liquid-crystal display (LCD) is a flat panel display, electronic visual display, or video display that uses the light modulating properties of liquid crystals. Liquid crystals do not emit light directly.
5.5.LED
A Light emitting diode(LED) is two lead semiconductor light source. It is a basic p-n junction diode ,which emits light .when a suitable voltage is applied to the leads, electrons are able to recombine with electrons hole with in the device , releasing energy in the forms of photons .This effect is called electroluminescence, and the colour of the light is determined by the energy band gap of the semiconductor
RESISTORS
A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. Resistors act to reduce current flow, and, at the same time, act to lower voltage levels within circuits. Resistors may have fixed resistances or variable resistances, such as those found in thermistors, varistors, trimmers, photoresistors and potentiometers. The current through a resistor is in direct proportion to the voltage across the resistor's terminals. This relationship is represented by Ohm's law:
I = V/R
where I is the current through the conductor in units of amperes, V is the potential difference measured across the conductor in units of volts, and R is the resistance of the conductor in units of ohms (symbol: Ω).To determine the value of a resistor without any test equipment, we must know the resistor color code. Each color stands for a number and place holder.
CAPACITOR
A capacitor (originally known as a condenser) is a passive two-terminal electrical component used to store energy electro statically in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors (plates) separated by a dielectric (i.e. insulator). The conductors can be thin films, foils or sintered beads of metal or conductive electrolyte, etc. The "non-conducting" dielectric acts to increase the capacitor's charge capacity. A dielectric can be glass, ceramic, plastic film, air, vacuum, paper, mica, oxide layer etc. Capacitors are widely used as parts of electrical circuits in many common electrical devices. Unlike a resistor, an ideal capacitor does not dissipate energy. Instead, a capacitor stores energy in the form of an electrostatic field between its plates.
There are various types of capacitors available in the market. Some of them are as follows:
Ceramic Capacitor
Electrolytic Capacitor
Mica Capacitor
Paper Capacitor
Variable Capacitor
Tantalum Capacitor
Film Capacitor