15-11-2012, 12:52 PM
PREPAID ENERGY METER WITH TARIFF INDICATOR
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Abstract
A scheme of Electricity billing system called PREPAID ENERGY METER WITH TARIFF INDICATOR can facilitate in improved cash flow management in energy utilities and can reduces problem associated with billing consumer living in isolated area and reduces deployment of manpower for taking meter readings. Every consumer can buy a memory card (is nothing but an EEPROM IC) with a password stored inside it using a MC program. The memory card is available at various ranges (i.e. Rs 50, Rs 100, Rs 200 etc?).In our project we have given the name for memory card as smart card.
When the consumer insert a smart card into the card reader which is connected in ?prepaid energy meter with tariff indicator kit. Then the card reader will read the stored information and delete the information from the EEPROM IC (smart card) using the MC program. So that the smart card cannot be reused by others. Suppose if a consumer buys a card for Rs.50/- he / she can insert this amount through the card reader so that prepaid energy meter with tariff indicator kit will be activated. According to the power consumption the amount will be reduced. When the amount is over, the relays will automatically shutdown the whole system. In our project we also have a provision to give an alarm sound to consumer before the whole amount is reduced.
Introduction
The Electrical metering instrument technology has come a long way from what it was more than 100 years ago. From the original bulky meters with heavy magnets and coils, there have been many innovations that have resulted in size & weight reduction in addition to improvements in features and specifications. Resolution and accuracy of the meter have seen substantial improvements over the years. Introduction of the digital meter in the later part of last century has completely changed the way Electrical parameters are measured. Starting with Voltmeters & Ammeters, the digital meter has conquered the entire spectrum of measuring instruments due to their advantages like ease of reading, better resolution and rugged construction. Of particular significance is the introduction of the Electronic Energy Meter in the mid eighties.
Now a days, the energy consumption and energy distribution has became a big subject for discussion because of huge difference in energy production and consumption. In this regard, energy consumers are facing so many problems due to the frequent power failures; another important reason for power cuts is due to the un-limited energy consumption of rich people. In this aspect, to minimize the power cuts and to distribute the energy equally to all areas, some restriction should have over the power consumption of each and every energy consumer, and according to that the Government should implement a policy, by introducing Autonomous Energy Meters everywhere in domestic sector. Hence, the need has come to think on this line and a solution has to be emerged out.
Electrical Metering Instrument Technology
Today the metering instrument technology grown up significantly, such that the consumed energy can be calculated mathematically, displayed, data can be stored, data can be transmitted, etc. Presently the microcontrollers are playing major role in metering instrument technology. The present project work is designed to collect the consumed energy data of a particular energy consumer through wireless communication system (without going to consumer house), the system can be called as automatic meter reading (AMR) system. The Automatic Meter reading system is intended to remotely collect the meter readings of a locality using a communication system, without persons physically going and reading the meters visually.
Low Current Performance
Most of the electromechanical meters tend to run slow after a few years and stop recording at low loads typically below 40% of their basic current. This is due to increased friction at their bearings. This results in large losses in revenue since most of the residential consumers will be running at very low loads for almost 20 hours in a day. Electronic meters record consistently and accurately even at 5% of their basic current. Also they are guaranteed to start recording energy at 0.4% of their basic current.
Low Voltage Performance
Most of the mechanical meters become inaccurate at voltages below 75% of rated voltage whereas electronic meters record accurately even at 50% of rated voltage. This is a major advantage where low voltage problem is very common.
Installation
The mechanical meter is very sensitive to the position in which it is installed. If it is not mounted vertically, it will run slow, resulting in revenue loss. Electronic meters are not sensitive to their mounting position.
Tamper
The mechanical meters can be tampered very easily even without disturbing the wiring either by using an external magnet or by inserting a thin film into the meter to touch the rotating disc. In addition to these methods, in the case of a single-phase meter, there are more than 20 conditions of external wiring that can make the meter record less. In the case of 3 Phase meter, external wiring can be manipulated in 4 ways to make it slow. Hence, any of these methods cannot tamper electronic meters. Moreover they can detect the tampering of meter by using LED.
Remote Metering of Energy Meters
The introduction of electronic energy meters for electrical energy metering has resulted in various improvements in the operations of utilities apart from the increase in revenue due to better recording of energy consumption. One such additional benefit is the possibility of reading the meters automatically using meter-reading instruments even without going near the meter. Meter reading instruments (MRI) are intelligent devices with built in memory and keyboard. The meter reader can download the energy consumption and related information from the electronic meter into the meter reading instrument either by connecting the MRI physically to the meter using their communication ports or by communicating with the meter from a distance using Radio Frequency (RF) communication media. RF communication method is similar to a cordless telephone, which is quite common these days. The meter and the MRI are provided with an antenna. When the meter reader presses a button on the MRI, it communicates with the meter through RF and asks for all the data that are preset.
Prepaid Energy Metering
Energy meters, the only direct revenue interface between utilities and the consumers, have undergone several advancements in the last decade. The conventional electro-mechanical meters are being replaced with electronic meters to improve accuracy in meter reading. Asian countries are currently looking to introduce prepaid electricity meters across their distribution network, buoyed up by the success of this novel methodology in South Africa. The existing inherent problems with the post-paid system and privatization of state held power distribution companies are the major driving factors for this market in Asia.
Over 40 countries have implemented prepaid meters in their markets. In United Kingdom the system, has been in use for well over 70 years with about 3.5 million consumers. The prepaid program in South Africa was started in 1992, since then they have installed over 6 million meters. Other African counties such as Sudan, Madagascar are following the South African success. The concept has found ground in Argentina and New Zealand with few thousands of installations.
General Description
Microcontroller
In this project work, the Microcontroller unit is designed with ATMEL controller, The ATMEL AT89C51 is a low power, higher performance CMOS 8-bit microcomputer, with 4K bytes of flash programmable and erasable read only memory (PEROM). Its high-density non-volatile memory compatible with standard MCS-51 instruction set makes it a powerful controller that provides highly flexible and cost effective solution to control applications.
Micro-controller works according to the program written in it. Most microcontrollers today are based on the Harvard architecture, which clearly defined the four basic components required for an embedded system. These include a CPU core, memory for the program (ROM or Flash memory), memory for data (RAM), one or more timers, as well as I/O lines to communicate with external peripherals and complementary resources — all this in a single integrated circuit. A microcontroller differs from a general-purpose CPU chip in that the former generally is quite easy to make into a working computer, with a minimum of external support chips. The idea is that the microcontroller will be placed in the device to control, hooked up to power and any information it needs, and that's that.
Memory Organization
A RAM stands for Random Access Memory, it has basically the same purpose of the RAM in a desktop computer, which is to store some data required during the execution time of different programs. While an EEPROM, also called FLASH memory is a more elaborated ROM (Read Only Memory) which is the memory where the program being executed is stored. Even if that's not exactly true, you can compare an EEPROM to the Hard-Disk of a desktop computer from a general point of view. The EEPROM term stands for Electronically Erasable and Programmable Read Only Memory.
In microcontrollers, like in any digital system, memory is organized in Registers, Which is the basic unit of construction of a memory. Each register is composed of a number of bits (usually 8) where the data can be stored. In the 8051 family of microcontrollers for example, most registers are 8-bit register, capable of storing values ranging from 0 to 255. In order to use bigger values, various register can be used simultaneously.
Software Description
A firmware developed in C language is programmed into the microcontroller’s code memory area. The firmware control’s the working of the entire hardware part. Usually the microcontrollers and the processors execute their instructions which are in machine code. In early days the applications were written in assembly language. The development of the huge application is very difficult by using the normal assembly language, because of their less readability. Later for the fast developments, the high level languages are introduced into the embedded system. C language is one of the most commonly used in the embedded system field. The ANSI C version is modified by adding specific hardware related functionality and information. The modified C language is commonly termed as Embedded C. The Keil Uvision 3 IDE is used for the development of the embedded system application development.