24-01-2011, 02:14 PM
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INTRODUCTION
1.1 General Background on AMR
Automatic meter reading (AMR) is the technology of automatically collecting data from energy metering devices (water, gas, and electric) and transferring that data to a central database for billing and/or analyzing. This saves employee trips, and means that billing can be based on actual consumption rather than on an estimate based on previous consumption, giving customers better control of their use of electric energy, gas usage, or water consumption.
This means that billing can be based on actual consumption rather than on an estimate based on previous consumption, giving customers better control of their use of electric energy. The Transmitter is connected to the meter and it counts the pulses from it and displays it over the seven segment display. It transmits the data over radio frequency. At the receiver end the data is received by a receiver module and the microcontroller will display it over the seven segment display.
1.2 Objectives of Projects
The main focus of this research and implementation project is to investigate currently existing adaptive routing techniques used in analogous telecommunication networks and from computer networks, to see what can be adopted and hence implementing them into the particular AMR system.
Development of a software model of the AMR system operation using chosen software will be used to demonstrate the findings and results. The model will incorporate a designed adaptive routing technique, running in a modeled AMR system over the low voltage power line distribution network. To do this the LV distribution network channel characteristics will need to be thoroughly investigated with suitable assumptions to be made to simplify the modeling process.
1.3 Overview of Chapters
The report is organized as follows. Firstly, Section One of the report covers a general background on Automatic Meter Reading System; this is followed by an outline of the project objectives. In Section Two a general description of the AMR technology is given, this includes its historical development and its present progresses. Section Three talks about the Automatic Meter Reading system. Section Four starts with the modes of theft & its control. Simulation & Results are presented in Section Five. The applicability of the model to practical problems is discussed in Section Six, with a conclusion in Section Seven. Any future development are discussed in Section Eighth.
LITERATURE REVIEW
In the following paper “A Low Complexity Multi carrier Proposal for Medium Rate Demanding Automatic Meter Reading Systems” [1], In Automatic Meter Reading (AMR) technology, electrical utilities (EUs) have been exploiting their own infrastructure to bill their customers in an efficient and economical way. Since the amount of data that has to be send is quite low related to the available time to perform this task, AMR applications have been demanding low bit rates. At this moment, EUs are exploring and demanding other services as load and alarm management, remote monitoring and disconnections, etc. In this context, the Low Voltage modems should provide more throughout while keeping the cost of the hardware low.
The results of this low complexity AMR technology are that in order to deploy an AMR network, the cost of the equipment on the customer premises and the added value services that the system provides are two key factors in its business case.
In the following paper “Load Allocation Based upon Automatic Meter Readings” [2], it describes the different methods by which distribution transformer loads can be allocated for power-flow studies. Individual distribution loads are calculated using four different methods of allocation. The results of the power-flow studies are compared to those determined using the actual customer meter readings.
The allocation methods to be studied are as follows:
• Daily kWH
• Monthly kWH
• Transformer kVA
• REA
In this paper, we described the characteristics of GPRS technology and Web Services technology, and introduced how to build the Web Services based GPRS Automatic Meter Reading System with these technologies. This system has such merits as: real time, wide coverage, open and easy to maintenance and extension. At present, this GPRS Automatic Meter Reading System has gained good application in practical work and been proved to be correct.
In this paper “Design of an Automatic Meter Reading System” [4], a microprocessor-based automatic meter reading system is implemented, which provides a cost-effective, reliable, and interference free data transfer between remote meter reading units and the utility control centre. The meter reading and management processes are free from human involvement. Based on the existing telephone networks, it is very flexible for the utility companies to access, service and maintain this meter reading system. A user friendly and window based user interface is designed which fully utilizes the personal computer's terminate and stay resident programming technique to achieve communications between the remote meter reading units and the personal computers in the utility control center. This paper describes the hardware design of the remote reading unit and the software implementation of the communication module and user interface.
The AMR system consists of Remote Reading Units (RRU) and Communication Front End (CFE) as shown in Fig. below. The Remote Reading Unit (=U) is an intelligent end-user premises device that constantly monitors and accumulates utility usage. It reports to the Communication Front End (CFE) through the telephone network either according to a predetermined schedule or on demand. The CFE collects information sent from the RRUs, and then assembles and transmits it to the utility host for administrative processing and billing.
The paper concludes on the note that An Automatic Meter Reading (AMR) system is developed, which consists of Remote Reading Units (RRU) and the Communication Front End (CFE). The capabilities of the AMR system are described. The functions and features of the AMR system can really be enhanced to include Home Automation (HA), Alarm/status monitor, and loop maintenance for telephone companies and remote electric load distribution/control. The potential opportunity of the AMR system seems to be bright.
AUTOMATIC METER READING SYSTEM
3.1 General Description
To survive in today’s business environment, companies have to be innovative. Whether it’s for the need to match the increasing competitions among electric utilities, or for meeting the ever-increasing demand from the end-users. The need to utilize electricity distribution, consumption, and to develop more efficient load management techniques have become increasingly more important on the day-to-day basis. One potential solution to all of those issues is the development of automatic meter reading systems, or AMR systems for short.
Like the name suggests, AMR refers to the collection of data from electronic meters or other devices and then automatically transmit the collected data via communication links without any human intervention. A general AMR system mainly consists of three parts - the meter interface module, the data concentrator system and a central computer system,
The meter interface normally consists of a backup power supply, together with meter sensors, controlling electronics, memory for storing data and a communication interface that allows data to be transmitted from this remote device to a central location. This communication interface is normally bi-directional and allows central computer signals to be received by the remote unit as well. The data concentrator is used for the transmission of data and controls the sending of signals between the meter interface units and the central office. In this particular system the communication page link takes the form of power line carrier technology, which is explained in the following section. The central computer system generally is made up from the host computer and the communication devices used for receiving and sending data to the data concentrators that exists the system.
AMR systems offers many advantages over the conventional metering system, such as the elimination of manual meter reading costs, improves customer service by reducing the mishandling of data. An English study shows that on average a meter reader achieves an information rate of only around 1 bit/s, which is highly inefficient in terms of modern standards.
AMR also reduces the problems and costs associated with reading meters at difficult-to-access locations. Additional significant cost savings can be achieved by identifying the tampering of meters; this includes reverse rotation, meter slowing and bypass. These can be detected because most of these AMR systems offer bi-directional communications, which allows the current meter data to be checked against the historical data for any suspicious discrepancies. Bi-directional communication is the very basic requirement to enable energy saving measures and value-added services to be introduced, such as allowing the AMR system to perform home alarm monitoring and call-out services. The application of automatic meter reading can also be incorporated into other types of meters, such as checking the status of parking meters. This application has now been used in Amsterdam, the Netherlands, where the status of parking meters are checked automatically by a central host on predefined time intervals
3.2 Ongoing Development of AMR’s
The earliest form of AMR systems developed were fixed carrier, analogue systems that was first put to trial in the 1950s using the ripple control signalling method. These systems were originally used for residential and commercial load control and tariff switching that helps utilities to offset peak demand to maintain their services. Back then the systems used conventional high voltage (HV) transformers to couple communication signals between 30 Hz to 50 kHz to and from the HV power lines. The ripple control systems deployed used carrier frequencies that were kept between 30 Hz to 1 kHz with their data transmission rates at a bandwidth of 10 Hz. All of the earlier systems were only capable of providing one-way communication.
New systems were not developed until the early 1980s. These systems offer a slightly higher data transmission rate. Then investigations were made in the mid 1980s by several utility corporations to analyze the characteristic properties of the electric grid as a medium for communication. Signaling frequencies in the range of 5 - 500 kHz were looked at. Main areas of investigation were the signal-to-noise levels affected by the power channel, as well as the attenuation of the signal by the transmission grid. As a result of the extent of the researches bi-directional communication was developed in the late 1980s and the early 1990s, where the present systems came onto the market during this time frame. The main difference in the newer system was the use of much higher frequencies (the wideband frequency range, often in the MHz range) and a substantial reduction of the signal levels. Through this development, two-way communication became realistic.
Today, advanced routing protocols are being implemented into AMR systems to make them adaptive to network changes and to achieve better management of data transmissions. The anticipated future development will mainly be looking at the use of frequencies in the GHz range, providing a much higher bandwidth and an even higher data throughput, possibly in the order of mega-bit/second speed range.
3.3 AMR system
It is the process by which data signals are superimposed on the power transmission lines. The point of signal injection is normally intended to be at the zone substation bus bar. Below is a diagram showing the overall structure of an AMR system:
3.5 AMR Technologies
There are many different technologies which are used in the AMR. Using these technologies data can be send from transmitting end to the receiving end. In our project we are using RF technology for transmitting the meter reading from one point to other point. The different types of technologies are described below. Out of which handheld technology is uses rarely.
3.5.1 Handheld:-
In handheld AMR, a meter reader carries a handheld computer with a built-in or attached receiver/transceiver (radio frequency or touch) to collect meter readings from an AMR capable meter. This is sometimes referred to as "walk-by" meter reading since the meter reader walks by the locations where meters are installed as they go through their meter reading route. Handheld computers may also be used to manually enter readings without the use of AMR technology.
3.5.2 Touch Based:-
With touch based AMR, a meter reader carries a handheld computer or data collection device with a wand or probe. The device automatically collects the readings from a meter by touching or placing the read probe in close proximity to a reading coil enclosed in the touchpad. When a button is pressed, the probe sends an interrogate signal to the touch module to collect the meter reading. The software in the device matches the serial number to one in the route database, and saves the meter reading for later download to a billing or data collection computer.
3.5.3 Mobile:-
Mobile or "Drive-by" meter reading is where a reading device is installed in a vehicle. The meter reader drives the vehicle while the reading device automatically collects the meter readings. With mobile meter reading, the reader does not normally have to read the meters in any particular route order, but just drives the service area until all meters are read components often consist of a laptop or proprietary computer, software, RF receiver or transceiver, and external vehicle antennas.
3.5.4 Fixed Network:-
Fixed Network AMR is a method where a network is permanently installed to capture meter readings. This method can consist of a series of antennas, towers, collectors, repeaters, or other permanently installed infrastructure to collect transmissions of meter readings from AMR capable meters and get the data to a central computer without a person in the field to collect it.
There are several types of network topologies in use to get the meter data back to a central computer. A star network is the most common, where a meter transmits its data to a central collector or repeater. Some systems use only collectors which receive and store data for processing. Others also use a repeater which forwards a reading from a more remote area back to a main collector without actually storing it. A repeater may be forwarded by RF signal or sometimes is converted to a wired network such as telephone or IP network to get the data back to a collector. Some manufacturers are developing mesh networks where meters themselves act as repeaters passing the data to nearby meters until it makes it to a main collector. A mesh network may save the infrastructure of many collection points, but is more data intensive on the meters. One issue with mesh networks it that battery operated ones may need more power for the increased frequency of transmitting.
3.5.5 Radio Frequency Network:-
Radio frequency based AMR can take many forms. The more common ones are Handheld, Mobile, and Fixed network. There are both two-way RF systems and one-way RF systems in use that use both licensed and unlicensed RF bands. In a two-way or "wake up" system, a radio transceiver normally sends a signal to a particular transmitter serial number, telling it to wake up from a resting state and transmit its data. The Meter attached transceiver and the reading transceiver both send and receive radio signals and data. In a one-way “bubble-up” or continuous broadcast type system, the transmitter broadcasts readings continuously every few seconds. This means the reading device can be a receiver only, and the meter AMR device a transmitter only.
Data goes one way, from the meter AMR transmitter to the meter reading receiver. There are also hybrid systems that combine one-way and two-way technologies, using one-way communication for reading and two way communication for programming functions.RF based meter reading usually eliminates the need for the meter reader to enter the property or home, or to locate and open an underground meter pit. The utility saves money by increased speed of reading, has lower liability from entering private property, and has less chance of missing reads because of being locked out from meter access.
3.5.6 Power Line Communication:-
AMR is a method where electronic data is transmitted over power lines back to the substation, then relayed to a central computer in the utility's main office. This would be considered a type of fixed network system the network being the distribution network which the utility has built and maintains to deliver electric power. Such systems are primarily used for electric meter reading. Some providers have interfaced gas and water meters to feed into a PLC type system.
3.5.7 Wireless Fidelity(Wi-Fi):-
Today many meters are designed to transmit using Wi-Fi even if a Wi-Fi network is not available, and they are read using a drive-by local Wi-Fi hand held receiver. Narrow-banded signal has a much greater range than Wi-Fi so the numbers of receivers required for the project are far fewer the number of Wi-Fi access points covering the same area. These special receiver stations then take in the narrow-band signal and report their data via Wi-Fi Most of the automated utility meters installed in the Corpus Christi area are battery powered. Compared to narrow-band burst telemetry, Wi-Fi technology uses far too much power for long-term battery-powered operation. Thus Wi-Fi is the efficient mean of communication in AMR technologies, which allows communication between the central data base and the end users, and defines the efficient reliability of the system. Thus offering a ultimate mean to fulfill the requirement.
MODES OF THEFT & THEIR CONTROL
4.1 Modes of Theft
It has been seen that there are 4 common methods of power theft as given below:-
• Bogus seals and tampering of seals.
• Meter tampering, meter tilting, meter interface and
• Meter bypassing.
• Changing connection.
• Direct tapping from line.
Due to introduction of modern electronic metering equipments, power thieves are utilizing more technological methods. Recent cases of power theft discovered by British inspectors included customers tunnelling out to roadside mains cables and splicing into the supply, a garage taking its night time power supply from the nearest lamp post and domestic customers drilling holes into meter boxes and attempting to stop the counter wheels from turning. Another method of Power theft is by keeping a strong magnet in front of the disc in the energy meter and thus arresting the rotation of the disc, connecting the load directly to the power line bypassing the energy meter. But, it can be avoided easily by providing a non magnetic enclosure.
4.2 Modern Detecting Tools
There are many modern tools that assist in power theft identification.
Some of them are:-
• Tamper proof seals and labels.
• Tamper resistant screws / locks.
• Check meter and remote meter readers.
• Tamper alarms and sensors.
SIMULATION AND RESULTS & DISCUSSIONS
5.1 What is MatLab
MATLAB is a high-performance language for technical computing. It integrates computation, visualization, and programming in an easy-to-use environment where problems and solutions are expressed in familiar mathematical notation. Typical uses include:
• Math and computation
• Algorithm development
• Modeling, simulation, and prototyping
• Data analysis, exploration, and visualization
• Scientific and engineering graphics
• Application development, including Graphical User Interface building
MATLAB is an interactive system whose basic data element is an array that does not require dimensioning. This allows you to solve many technical computing problems, especially those with matrix and vector formulations, in a fraction of the time it would take to write a program in a scalar no interactive language such as C or Fortran.
The name MATLAB stands for matrix laboratory. MATLAB was originally written to provide easy access to matrix software developed by the LINPACK and EISPACK projects, which together represent the state-of-the-art in software for matrix computation.
MATLAB has evolved over a period of years with input from many users. In university environments, it is the standard instructional tool for introductory and advanced courses in mathematics, engineering, and science. In industry, MATLAB is the tool of choice for high-productivity research, development, and analysis.
MATLAB features a family of application-specific solutions called toolboxes. Very important to most users of MATLAB, toolboxes allow you to learn and apply specialized technology. Toolboxes are comprehensive collections of MATLAB functions (M-files) that extend the MATLAB environment to solve particular classes of problems. Areas in which toolboxes are available include signal processing, control systems, neural networks, fuzzy logic, wavelets, simulation, and many others.
5.2 For Single-Phase (1-Phase) Load:-
Here in the AMR system the Meters data such as Meter number, Active Power and Distortion in waveform are transmitted to the remote Server On the basis of TDM technique. To implement the TDM the ‘Repeating Sequence Stair (RSS)’ is used. Set values for RSS are ‘1’ and ‘2’,with a sample time of 0.002s.It would select the Input port of Switch named as ‘Data selection Switch’. When the RSS output is ‘1’ SubSystem1-is selected and when RSS output is ‘2’ SubSystem2-is selected.
Bill of Active Power used is calculated on the basis of the power used by the individual customer, which is calculated by the subsystem-Tariff.
APPLICATIONS OF AMR & IT’S BENEFITS
6.1 Applications of AMR
As technology continues to improve in price/performance, the number of municipal utilities implementing automatic meter reading (AMR) systems continues to grow. Today, most AMR deployments are “walk-by” or “drive-by” systems. A battery-operated transmitter in each meter sends a radio frequency (RF) signal that is read by a special receiver either carried by hand or mounted in a vehicle. These solutions require a much smaller staff of meter readers, who merely need to walk or drive by the many meters in any neighborhood. Although this form of AMR is an enormous improvement over manual meter reading, continued high labor and vehicle costs are driving the industry to an even better solution.
Among the many advantages are the ability to monitor daily demand, implement conservation programs, create usage profiles by time of day, and detect potentially hazardous conditions, such as leaks or outages. But there is still one drawback with these AMR deployments: the costly network backhaul required by leased lines or cellular services from a local telephone company, or Power Line Carrier (PLC) solutions from the local power company.
AMR is the remote collection of consumption data from customers’ utility meters using telephony, radio frequency, power lines and satellite communications technologies. AMR provides water, gas and electric utility-service companies the opportunity to increase operational efficiency, improve customer service, reduce data-collection costs and quickly gather critical information that provides insight to company decision-makers.
6.2 Benefits of AMR
Benefits of AMR:-
The automatic meter reading (AMR) technology is very useful in many applications. By using AMR technology we can accommodate a lot of benefits. Some benefits of AMR are as follow-
Electrical Company Benefits:-
• Smart automated processes instead of manual work.
• Accurate information from the network load to optimize maintenance and investments.
• Customized rates and billing dates.
• Streamlined high bill investigations.
• Detection of tampering of Meters.
• Accurate measurement of transmission losses.
• Better network performance and cost efficiency.
• Demand and distribution management.
• More intelligence to business planning.
• Better company credibility.
Customer Benefits:-
• Precise consumption information.
• Clear and accurate billing.
• Automatic outage information and faster recovery.
• Better and faster customer service.
• Flag potential high consumption before customer gets a high bill.
CONCLUSIONS
Today utility owners are using energy based tariffs when distributing electricity. If implementing a load-demand based tariff the possibilities to control the consumption pattern increase because the economical revenues become more connected to the peak loads within the system. The new demand-based tariffs meet the Swedish regulations as long as the total yearly revenue does not exceed the fixed limit. However, the monthly revenues are varying depending on which tariff is being modelled. The demand based tariffs move the revenues to the high-peak period, November - March, and the utility operator gets a good matching between system peaks and revenues. Further investigations needs to be done in order to determine the adequate pricing level from the utility operators' as well as the customers' points of view.
FUTURE DEVELOPMENTS & ENHANCEMENTS
The simulated model was far from a completed model and was intended to fulfil mainly the task:
To demonstrate the findings in a software format and to implement adaptive and optimal discovery of Time-Division Multiplexing (TDM), for Automatic Meter Reading System.
As shown in the graph below, with development in the field of AMR/AMI will result in the reduction of Investment/Service Cost and will lead to better Functionality.
