Web Enabled Meter Dessertation

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CHAPTER 1

Electricity and its metering An overview

1.1 IntroductionElectricity, since its invention, has always been one of the fundamental

requirements for any modern civilization and its development. It is now at the heart of any

property, whether it is residential, commercial or industrial. Thinking for a while, we can

imagine how deep electricity goes through our lives. Factories, mills, laboratories, commercial

institutions, traffic, communication, home lights, televisions, PCs and cell phones are just few

examples on the present situation of Electricity Empire.

Since beginning, research and development in the field of electrical energy has been

concentrated on its generation, transmission, distribution, protection and line losses, etc.

But, in all the generations of electrical power technologies, no significant changes in

measuring methods of electricity consumption were noticed. Electric meter remains the very

basic and traditional meter in its shape or functionality. It had nothing to do as a part of the

whole electrical system except the electrical energy consumption calculation in a very

conventional manner. The conventional meters in two different forms, are shown in Fig.1.1.

Fig.1.1 Conventional Electric Meters

But the scene turned far different in the last few years particularly from the last decade of the

last century. Main causes for this, envisage are:

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Resources necessary to produce electricity particularly fossil fuels are

depleting rapidly,

Electricity consumption is increasing in geometrical progression,

World population is increasing day by day and proportionally the demand for

electricity is also increasing many folds. Change in human mindset and life style with more and more demand of

comfort has further loaded the electric grid in terms of electric supply required

for air conditioners, refrigerators, fans, ovens mixer grinders etc.

Cumulative effect of all the above factors has enhanced the industrial and

commercial growth world over, which is further reflected in tremendous

demand for electricity.

Transmission, distribution losses and poor efficiency of generating systems

have proved the term that conserving three units of electricity is equivalent to

producing five units. The total emphasis is thus diverted towards the

conservation of electricity.

In view of the above, new field of research and development has emerged in the form

of metering technology. The objectives of such technology were not limited merely to

measure the consumed units of the electricity but far above.

1.2 Objectives of electricity metering in todays perspective

Metering of utilities, including electricity, should be designed to allow the following

objectives to be met with in the existing system [1]:

To provide sufficient data for allowing correct financial charges to be made to each

consumer with appropriate periodicity,

To provide sufficient data for periodic energy forecasts;

To provide sufficient data for yearly energy budget standards;

To provide sufficient data to take corrective action on energy-usage control, as per

need,

To provide sufficient data to measure the efficiency of all major sub-systems in the

utility area.

To provide detail about the quality of electricity

To provide information in case of tempering of any kind;

1.3 Conventional System and its Drawbacks

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With the passage of time and also need, conventional meters have undergone changed

shape and design. Electromechanical induction meters have gradually been replaced by

electronic and digital meters. In India it has become mandatory to use the electronic meters in

all new installations. Commercial and Industrial institutions are required to get digital meters

installed in their premises.

Electronic and digital energy meters are shown in Fig.1.2 and 1.3 respectively.

Fig.1.2 Electronic Energy Meter Fig.1.3 Digital Energy Meter

1.5 Alternative systems for Meter Reading

Various drawbacks and limitations of the conventional manual metering system motivated the

technologists to go for alternative automatic approach for determining the electricity

consumption. The primary driver for the automation of meter reading is not so much to reduce

labour costs, but to obtain data that is otherwise unattainable. Mostly electric meters,

especially in multystoried buildings in metro cities, are located in places that are inaccessible

to the meter reader and require an appointment with the homeowner for the purpose of meter

reading. Electricity tends to be more valuable commodity as compared to others, and the

consumed energy must be measured through actual readings instead of estimated readings.

This has driven the electricity utility companies to consider for automation. This is commonly

called Automatic Meter Reading orAMR.

1.6 Types of Automatic Meter Reading (AMR)

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Advent of electronic and digital energy meters facilitated the process of automatic meter

reading. AMR may be based on various methods and designs. Few important methods are

given below:

On-site automatic meter reading

In this method, 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 serialnumber to one in the route data-base, and saves the meter

reading for later download to a billing or data collection

computer. Since the meter reader still has to go to the site of the

meter, this is referred to as "on-site" AMR.

Power Corporation Ltd, in the state of Uttarakhand, also uses similar method for

the purpose of recording of data in industrial and domestic units. Instead of using

rf signal optical contact using IR is being used as shown in Fig.1.4. This method

avoids the chances of recording incorrect reading due to human error. But even

this method still requires the exercise to access each and every meter in person.

Switch IR Port

Fig. 1.4 Digital meter being used in the state of Uttarakhand

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AMR using Mobile Van

Mobile or "Drive-by" meter reading is used 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/transceiver,

and external vehicle antennas. Wi-Fi technique is also implemented for this

type of data collection system.

Power Line Communication

It is a method in which 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 as 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.

Web-Enabled AMR

Broad-band availability at nominal cost and without much complexity, web-

enabled AMR system is emerging at very fast pace. In this method electric

meter is made net enabled so that useful data from the meter is periodically

uploaded to the relevant site of the utility, from where analysis and billing job

be performed automatically. The author has made a successful attempt to

utilize this technique for executing the present work.

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CHAPTER 2

Literature Review

2.1 Introduction

Severity of energy crises was realized in the decade of 1990, hence reforms in all the related

fields started only after that. Most of the literature published there after, belongs to the diverse

fields of new sources of energy, fuel efficiency, fuel economy etc. The topic which the author

has undertaken in this work, belongs to the energy saving and monitoring techniques.

Literature shows that various efforts are being made constantly at laboratory as well as in the

field level to demonstrate a usefulmeteringsystem. In consequence to this, use of electronic

(digital and analog) meters in all upcoming domestic and all commercial locations have been

made mandatory.

2.2 Literature Survey

The author has reviewed a large number of literature including research papers, technical

broachers, specification sheets, government rules and project reports in connection with the

proposed work. These are described below:

Wayne L Stebbins emphasized in [1] on managing energy in industry, with many test

measurements and recordings to determine usage patterns before deciding what can

be done to reduce consumption. The author also mentioned the developments in digital

metering over the past several years that have significantly improved both meter

accuracy and repeatability. The advent of microprocessor based test devices and

meters has greatly improved the ease of operation, making the equipment "user-

friendly" even to the novice. Details presented in this paper include an introduction to

metering objectives, practical metering applications, latest metering techniques to

employ in the process of measurement and certain pitfalls in the process that should be

avoided.

Gambhir Ajay has mentioned in [2] in year 2001, regarding the use of internet enabled

modem chip for the benefit of the service provider and the end user. As per the author, de-

regulation, new technologies, energy shortages, price increases, heightened attention to

conservation and increased global competition are all causing sweeping changes to the utility

industry, in both residential and commercial sectors. These changes heighten the importance

of load management and motivate consumers to change their usage patterns to balance theloads. In order to efficiently adapt to these changes and facilitate load balancing, utility

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companies and their customers require new management and control capability. Advanced

communications techniques can provide these new capabilities and improve operating

efficiency.

Reaz M.I.,Rahman et al. reported in [3], the development of an efficient algorithm that

implements a flexible and affordable digital energy meter intended for home usage. As

a first step, the algorithm is downloaded into an FPGA prototype board. The algorithm

architecture comprises four main modules: power, energy, billing and display. Two

digitized inputs, which are assumed to come from single-phase voltage and single-

phase current, will be fed into the digital energy meter and the output is expected to be

the energy consumed and the corresponding billing. The timing analysis and circuit

synthesis, have been performed on suitable platforms. Using digital synthetic test data

it has been proven that the model is tested successfully. This work forms the first

phase of developing a commercial but affordable digital energy meter for home usage

employing digital techniques. Another step will be to make the meter communicable

with remote control unit.

Application note, Atmel, AVR465 in [4] describes a single-phase power/energy meter

with tamper logic. The design is such that, the meter measures active power, voltage,

and current in a single-phase distribution environment. It differs from ordinary single-

phase meters in that it uses two current transducers to measure active power in both

live and neutral wires. This enables the meter to detect, signal, and continue to

measure reliably even when subject to external attempts of tampering. The heart of the

meter is an AVR microcontroller. All measurements have been carried out in the

digital domain and measurement results are available in the form of frequency-

modulated pulse outputs and as plain-text values, accessible over the USART

interface. This enables the design to be used in cost-effective applications based on

mechanical display counters. Alternatively, the design easily fits more computerized

applications with features such as remote reading, demand recording, multiple tariffs,

and several others.

Nagarju M. et al. mentioned in [5], regarding Smart meteringusing the IEEEP1451.2

Protocol, Energy meter standards have also been described in this paper along with the

requirements for such a meter and use of the technique for the quality power

measurement are also mentioned.

M/S Energy Tracking, NJ, USA have produced a web enabled meter. Installation and

Operation procedures of this are mentioned in [6]. This manual describes the

installation and operation procedure for companys standard commercial meter. This

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meter consists of an embedded network module that has a web-server and is capable of

transmitting reports via Email and /or FTP. But it has no facility to upload the site of

the concerned utility periodically. This can send periodic reports only.

Paranhos I. et al. in [7] emphasized that nowadays, the control over every minimal cost

is being very important for the market competition. Since the electric energy billsrepresent a great amount of expenses for the companies, the monitoring of the power

quality helps to lower the energy costs and to prolong the machines life. But, not

every company can pay for an expensive resource that helps to minimize the expenses.

This paper presents study and development of a low cost electrical energy monitoring

system, that consists of a digital energy meter, a software for the system management,

a data-base to store the measurements and a web-page to monitor the energy quality

from anywhere, through the internet. Algorithms based on calculus, were proposed for

implementation. Physical environment and communication protocols have also been

proposed.

Coca Eugen, in [8] presented an energy meter reading interface application. Energy

pulses for every quarter of an hour are counted by a microcontroller and stored on a

non-volatile medium, all required data being transmitted to the energy dispatcher

control unit via an Internet communication embedded controller. The idea may be

applied in power substations but is also useful for medium-size consumers who have

multiple exchange points with the energy supplier, equipped with standard meters that

are able to provide only free potential relay contacts for billing applications. Using

standard Ethernet network communications is also a very new idea in this field, all

data may be available in real time to the energy management unit.[8]

Markow John, in [9] described microcontroller based energy metering using the IC

AD 7755. The author also described how the Energy Meters IC AD 7755 could be

used in three-phase energy metering with power outage detection and measurement

backup, remote, automated, multiple-rate metering.

Specification sheet of IC ADE 7754 in [10], described multifunction poly-phase

energy metering IC with serial port interface, from Analog Devices. It described the

use of this IC as interface between measuring equipment and serial port of the

computer. This can be used as an analytic tool for electrical measurement.

Specification sheet of IC ADE 7758 from Analog Devices, in [11],described

multifunction poly-phase energy metering IC with serial port interface. The

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specifications for the microcontroller based IC ADE 7758 to be used as analytic tool

for electrical measurement, are also described in this.

Loss P.A.V. et al. presented in [12] a microcontroller based energy meter, a totally

electronic single-phase energy meter for residential use, based on Microchip

Technology Inc. PIC family of microcontrollers. In this paper author explained thebasics of energy measurement, in integration with the use of microcontroller. This

paper has demonstrated the possibility of measuring the electrical energy consumption

with a microcontroller based meter, as an alternative to the conventional

electromechanical meters.The design proposed in the said paper takes into

consideration the correct operation in the event of an outage or blown out, by

recording the energy consumption in EEPROM memories internally available in the

microcontroller. When the supply is restored, the energy consumption computation is

properly initialized. Also, a four digit display is used to show the energy consumption.

Chavan S et al in [13] proposed an open standard protocol for networking of energy

meters under the simple network-management protocol (SNMP) environment. Since

the SNMP is quite popular for network enabling uninterruptible power supplies, the

necessary support hardware and software already exist. Hence, migrating energy meter

connectivity to the transfer control protocol/Internet protocol-based SNMP would be

an easy task. A sample network has been created under the LabVIEW virtual

instrumentation environment and studied to validate the proposed open standard

protocol for networking of energy meters.

Ayurzana Odgerel et al. in [14] described an automatic remote water measurement

system. This system sends remotely collected water meters data automatically from

the transmitter with CDMA modem through SK-Telecom network. The water meter

data are received through LAN TCP/IP and displayed as test file on Internet browser.

This paper is all about the water meter reading but the objective is same, that can also

be used for electricity measurement.

Cao Liting et al. in [15] suggested the mesh technology for cluster of networked

meters. As per the authors, meters at a particular location are networked together and

connected to one gateway server from where wireless link is made to the main control

centre. This paper gave an insight to the connections of the meter.

Cao Liting et al. in [16] mentioned how to network remote meter reading system,

based on wireless technology. Heart of the system is ARM MPU S344B0X with

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embedded software system. In this system different residences are connected with

local management centre by GSM medium, where as local management centre was

connected with utility using wired or wireless technology.

Artur Krukowski et al. in [17] presented an alternative route to transfer Simulink

model into VHDL. Such an idea would be a very attractive way of designing test chipsquickly. It takes less time to get the final synthesised version from the Simulink

model. However the process of transferring the design on FPGA chip, has not been

mentioned in this report.

Naphade S.P. in [18], has focused, on the cost reduction benefits of the automatic

meter reading. This is a motivational paper to promote the use of automatic meter

reading further.

Doraswami Anand in [19] has insisted upon the need for an electronic meter at

domestic as well as industrial level.

Specification sheet [20] provided by Atmel for 8-Bit microcontroller IC AT89S52

with 8KB in system programmable flash memory provides the methods to develop the

circuit as per the requirement.

Specification sheet [21] provided by Atmel for Energy metering IC ADE 7755 with

pulse output, provides great insight for power measurement in digital domain. This

paper also provides the way to incorporate microcontroller in the process of energy

measurement.

2.3 Inferences Drawn out of the Literature Survey

A thorough literature survey revealed that after the decade of nineties, concern over the need

for accurate and transparent electricity measurement [19] has arisen. Simultaneously

manufacturers have started developing electronic products to suit this need [10,11,16,20].

Main observations as inferences drawn out of the literature survey are summarized below:

Electric energy generation and demand are not comparable. Demand is much more

than the generation. This gap is increasing day by day and there is no way out because

conventional resources are limited. Non-conventional sources are not at the state to

feed the large demand. In view of this, conservation of electricity is the only probable

solution.

Proper data acquisition and correct measurement of the consumption are necessary for

demand analysis, fault finding and on the top, executable planning for the future.

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There should be a phased program to replace the inefficient electromechanical meters

by the precise electronic meters,

Manual meter reading is not feasible because of the large number of users staying in

multistoried buildings and none is available at the home during working hours.

Increased literacy rate and awareness of the consumer rights, have prompted thetransparency requirement in energy reading also. Every consumer has the right to

know the actual consumption of electricity measured.

The methods for collecting data regarding use of electric energy, must be transparent,

and there must be proper record of the collected data and which may be open to the

consumer,

The technology is now advanced enough and there are various electronic products

available in the market which along with the latest technical knowhow, may be used to

fabricate the system for achieving the objectives of transparency and efficient datacollection,

Among others, Atmel Corporation US has already been engaged in producing low cost

microcontrollers which, along with suitable software and hardware support, can

economically be used for this purpose of fabricating such systems [20].

Atmel Corporation have also produced front end IC ADE 7755 that can be used in an

energy metering system as an ideal replacement for the conventional electromagnetic

energy meters [21].

Work on the net enabled electric meters, is already in pipeline. Products based on the

preliminary designs, are already available in the market [11,14,16].

2.4 Scope of the Work

The scope of the present work is limited to the use of microcontroller Atmels AT 89 S 52

along with support hardware like serial port interfacing IC HIN 232, Energy metering IC ADE

7755, external serial EEPROM IC 2402 and 16 x 2 LCD display IC. Suitable software to

program the microcontroller and to capture and display the data on the screen of the computer

working in server mode, are also used. Software are responsible to read the consumption of

electrical energy from the hardware and display number of consumed units at site as well as to

transmit the data to the web page of the internet for electricity supply company and the

consumer also.

The present work is limited to the following:

Measurement of the single- phase parameters,

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Voltage, current and power factor have been taken as the main parameters sampled

for processing,

Electrical energy consumption has been recorded and transferred to the utility with

time stamp,

Sampling of the above data periodically and provision of maintaining the records, for at leastone year on the computer itself.

Data processing is performed with the use of microcontroller AT 89 S 52 module.

2.5 Problem Definition

Design, development and implementation of a reliable, efficient and cost effective

Web Enabled Automatic Electrical Energy Meter comprising microcontroller based

hardware and compatible software to capture, transmit, display and maintain the record of the

electricity consumption data of a particular user on the internet page.

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CHAPTER 3

Power and Energy Measurement

3.1 Energy Measurement

Active power is defined as the power used by a device to produce useful work.

Mathematically it is the definite integral of voltage, u (t), times current, i (t),

Active Power Definition:

P = x i (t) = U x I x cos () 3.1

Here U and I are the respective voltage and current root mean square (RMS) values of in

coming signal and is the phase lag between current and voltage.

The discrete time equivalent is:Active Power Definition in Discrete Time:

P = x i (n) 3.2

Here u(n) and i(n) are the sampled instances of u(t) and i(t) and N is the number of

samples. Small n indicates the discreet nature of the equation. Active power is calculated

simply as the average of N voltage-current products. It can be shown that this method is valid

for both sinusoidal and distorted waveforms. The implementation uses 32-bit data types

(signed long) for storing accumulated data. The result is stored as a floating-point number.

When the meter has been calibrated, the active power results are in units of watts.

3.2 Theory of Power Measurement in Digital Domain

In a common digital system for measurement of the power, voltage and currents are

monitored using resistor and current transformer respectively as transducers. The two ADCs

digitize the voltage signals from the current and voltage transducers. These ADCs are of 16-

bit, second-order - with an oversampling-rate of fairly high frequency. A high-pass filter in

the current channel removes any dc components from the current signal. This removal

eliminates any inaccuracies in the active power calculation due to offsets in the voltage or

current signals.

The active 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. To extract the active power component (that is, the dc component), the instantaneous

power signal is low-pass filtered.

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Fig. 3.1 Power measurement and conversion to frequency

Fig. 3.1 shows the two inputs CH1 and CH2 corresponding to current and voltage respectively.

Current value at CH1 is usually read by the current transformer. Input voltage is amplified

with programmable gain amplifier (PGA) and then goes to sigma-delta second order

modulator with a sampling frequency of 900 kHz. Then signal is passed through high pass

filter and then delayed to compensate phase shift in filter.

In second input CH2, available voltage is proportional to the load voltage. This voltage

is modulated with second sigma-delta modulator. Then instant current and voltage values are

digitally multiplied to get instant active power. Results are then passed through low pass filter

to get current active power. Instantaneous power value is converted into proportional

frequency and this frequency is made available at output terminals F1. Another terminal F2

has the same frequency but in inverted phase. Frequency signals at F 1 and F2 are applied to

drive low rpm motors such as stepper motor.

Another digital to frequency output terminal is CF. Signal frequency available at this

terminal is proportional to the instantaneous active power. This frequency is higher than

frequency available at terminal F1, and called calibration frequency (CF). This high output

frequency has shorter integration time, and this is useful for system calibration purposes

under steady load conditions. The same CF output is taken to run external microcontroller

device for manipulation and display purpose.

Having obtained this data there are many ways to display and register energy. One of

the ways is to use stepper motor and other one is to implement microcontroller based display.

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3.3 Power Factor Consideration

The method used to extract the active power information from the instantaneous power

signal (that is, by low-pass filtering) is valid even when the voltage and current signals are not

in phase. Fig. 3.2(a) displays the unity power factor condition and Fig. 3-.2 (b) at 0.5 power

factor (PF), that is, current signal lagging the voltage by 60. Assuming that the voltage and

current waveforms are sinusoidal, the active power component of the instantaneous power

signal (that is, the dc term) is given by:

P = x Cos (60) 3.3

Fig. 3.2 DC Component of Instantaneous Power Signal

The active power calculation method also holds true for non-sinusoidal current and

voltage waveforms. All voltage and current wave-forms in practical applications have some

harmonic content. With the use of the Fourier Transform operation, instantaneous voltage

and current waveforms can be expressed in terms of their harmonic contents.

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3.4 Energy Measurement with the Microcontroller Interface

The easiest way to interface the microcontroller with power measurement module is to use

the high calibration frequency( CF) output of the power IC. With full-scale ac signals on the

analog inputs, the output frequency on CF is approximately 5.5 kHz. Fig.3.3 illustrates one

scheme that can be used to digitize the output frequency and carry out the necessary averaging

for estimating the amount of energy consumed.

Fig.3.3 Power IC and Microcontroller Unit Interfacing

The frequency output at terminal CF of the power measuring IC, is connected to a

microcontroller unit (MCU) counter, which counts the number of pulses in a given integrationtime that is determined by the internal timer of the MCU. The energy consumed during an

integration period is given by:

Average Frequency Average Active Power =

Energy = Average Power x Time = x Timer = Counter

For the purpose of calibration, this integration time can be 10 to 20 seconds to

accumulate enough pulses to ensure correct averaging of the frequency. In normal operation,

the integration time can be reduced to 1 or 2 seconds depending on the situation, for example,

on the required update rate of a display. With shorter integration times on the MCU, the

amount of energy in each update may still have some small amount of ripple, even under

steady load conditions. However, over a minute or more, there is a chance that the measured

energy has no ripple.

The circuit also includes a no load threshold and start-up current feature that

eliminates any creep effects in the meter.

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Any load generating a frequency lower than a minimum frequency would not cause a

pulse to be issued on terminals F1, F2, or CF of power IC 7755. The minimum output

frequency is given as 0.0014% of the full-scale output frequency.

International Electro-technical Commission standard IEC 1036 (1990) for alternating

current static watt-hour meters for active energy, states that the meter must start up with a load

current equal to or less than 0.4% nominal current. For a 5 A meter, 0.4% is equivalent to 20

mA. Therefore counting will start at 20 mA of the load current value.

Calculating and displaying power information always has some associated ripple that

depends on the integration period used in the microcontroller unit to determine average power

and also the load. For example, at light loads, the output frequency can be 10 Hz. With an

integration period of 2 seconds, only about 20 pulses are counted. The possibility of missing

one pulse always exists because the IC ADE7755 used in the current project, output frequency

is running asynchronously to the microcontroller unit timer. This possibility results in a 1-in-

20 (or 5%) error in the power measurement. Looking at this point in the present case 3600

pulses per kWh is maintained as the standard.

3.5 Microcontroller Unit

In industrial and domestic products, microcontroller is a device that can perform

automatic control, data storage and processing in cost effective and efficient way.

Microcontroller provides smaller size, flexible configuration, fast implementation of desired

job and low power consumption [20]. The microcontroller has changed the architecture of

instrumentation, measurement and control due to its custom build configuration and

computation capability. Microcontroller allows controlling the timing sequence of the

machines, processes and can carry out simple arithmetic and logic operations.

Microcontroller is an embedded system having all the functional blocks which can

fulfill the general need of automation. Microcontroller consists of central processing unit

(CPU), Airthmatic and logic unit (ALU), serial port, Accumulator, Timer, Stack and many

more functional blocks on a single chip. All these blocks can be programmed as per our

requirement. In other words microcontroller can be called as a single chip microprocessor.

Microprocessor require additional memory and other components to be added externally, but

microcontroller has all required components integrated in the chip. It is therefore

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microcontroller system is fabricated for a specific single job. Microprocessor based system is

fabricated keeping in view of its versatility for millions of jobs.

There are many brands of microcontrollers available commercially in the market. Mostpopular are Intel 8051, MCS -51, ATMELs 89C2051, and ATMELs 89S52. Fig.3.4 shows

the block diagram of a general microcontroller.

Fig. 3.4 Block Diagram of Generalized Microcontroller

As shown in Fig. 3.4 a microcontroller has the following functional blocks:

CPU: Central Processing Unit

I/O: Input /Output

Bus: Address bus & Data bus

Memory: RAM , ROM and/or Flash memory

Timer Oscillator

Interrupt

Serial Port

Parallel Port

Microcontroller has CPU, RAM, ROM, I/O and Timer on a single chip for cost

effectiveness, power and space consideration. Microcontroller is made for one application and

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it remains dedicated to the same work. Its functionality seldom changes. That is why it is

known as a dedicated or stand alone controller.

In the current work, author has used ATMELs AT89S52, an 8-bit Microcontroller

with 8K Bytes in-System Programmable (ISP) Flash.The device is manufactured using high-

density nonvolatile memory technology and is compatible with the industry-standard 80C51

instruction set and pin configuration. The on-chip Flash allows the program memory to be

reprogrammed in-system or by a conventional non-volatile memory programmer.Fig.3.5

shows the pin configuration of AT 89 S 52 microcontroller.

Fig. 3.5 Pin configuration of microcontroller AT 89S52

3.6 Microcontroller Programming Hardware and Software

A micro-controller can be compared to a small stand alone computer; it is a very

powerful device, which is capable of executing a series of pre-programmed tasks and

interacting with other hardware devices. But microcontroller requires some software in terms

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of the program burned into its memory before the execution of the project. This software

guides the hardware what and when to perform a desired action. In case of the current project

the microcontroller Atmels 89S52 is based on the core technology of Intels 8051 which is

compatible with the Intels assembly language used for its microprocessors and

microcontrollers. Long programs as with the current case may also be written in higher levellanguage such as most common language C with suitable software and hardware support.

The C source code is very high level language, meaning that it is far from being at the

base level of the machine language that can be executed by a processor. This machine

language is basically just zeros and one's and is written in Hexadecimal format, thats why it

is called HEX files. KEIL u-Vision is the name of proprietary software dedicated to the

development and testing of a family of microcontrollers based on 8051 technology, like the

89S52 which the author has used along this project. An evaluation version of KEIL was down

loaded from the website: http://www.keil.com/c51/.

KEIL software is used to convert a C program to machine language, it takes several

steps however, and the main idea is to produce a HEX file at the end. This HEX file was then

used by the 'burner' to write every byte of data at the appropriate place in the Flash memory of

the 89S52.

The Code memory array of the AT89S52 can be programmed using the serial In System

Programming (ISP) interface. The serial interface consists of pins SCK, MOSI (input) and

MISO (output) of the microcontroller IC 89S52. Before a reprogramming sequence can occur,

a Chip Erase operation is required. Fig.3.6 depicts the schematics of the connections made to

serially program the microcontroller.

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USB using USB to RS232 converter. In the block diagram five pull resistors are visible, which

makes the in system input and output pins MISO and MOSI pulled up to high status if data is

not available.

The Programmer is powered from the target board ie. microcontroller under programming. The

AT89C2051 microcontroller is programmed with the programmesr firmware. The PC softwareavailable with it, is easy to use and is designed especially for batch programming. This

hardware supports the microcontroller AT89S52.

The crystal for the programmer board is of the rating of 11059,2 kHz. To use this frequency S

(Slow mode) in the command line has been included. All command line parameters are

displayed by the program itself.

3.7 Display System

Electrical energy consumption depends upon the value of voltage and current at the

measuring input and output terminals. According to these values instantaneous active power is

calculated and in proportion to instantaneous power, pulses are produced. The number of

pulses and corresponding energy consumption is displayed on an LCD panel.

Microcontroller interfaces with this 5 volts display screen. In the current data

regarding the consumption of the electrical energy is made available on the internet but it is

also desirable to show the instant data locally at the site of meter installation. This objective is

met with the use of LCD panel, which shows pulse counts and the kWh consumed. The LCD

panel unit receives character codes (8 bits per character) from the microcontroller, latches the

codes to its display data RAM (80-byte DD RAM for storing 80 characters), transforms each

character code into a 5 x 7 dot-matrix character pattern, and displays the characters on its

LCD screen.

The LCD unit incorporates a character generator ROM which produces 160 different 5

x 7 dot-matrix character patterns. To display a character, positional data is sent via the data

bus from the microcontroller to the LCD panel, where it is written into the instruction register.

A character code is then sent and written into the data register. The LCD unit displays the

corresponding character pattern in the specified position. The LCD unit can either increment

or decrement the display position automatically after each character entry, so that only

successive characters codes need to be entered to display a continuous character string. The

display/cursor shift instruction allows the entry of characters in either the left-to-right or right

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to left direction. Since the display data RAM (DD RAM) and the character generator RAM

(CG RAM) may be accessed by the microcontroller, unused portions of each RAM may be

used as general purpose data areas. The LCD unit may also be operated with dual 4-bit or

single 8-bit data transfers, to accommodate interfaces with both 4-bit and 8-bit

microcontrollers.

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3.8 PC and Web Interfacing

Web interfacing can be achieved using microcontroller programmed in a way to

interface with the PC through serial port. In case of serial port interfacing all the data remains

available at the buffer of the serial port. To fetch and display the data from the serial port

following software packages are used

Visual Basic : Visual Basicis a tool that allows us to develop Windows (Graphic User

Interface - GUI) applications. The applications have a familiar appearance to the user.

It is an event-driven application, which means the program code remains idle until

called upon to respond to some event such as button pressing, menu selection, etc.

Visual Basic is governed by an event processor. Nothing happens until an event is

detected. Once an event is detected, the code corresponding to that event (event

procedure) is executed. Program control is then returned to the event.

Some important features of the Visual Basic are as follows:

Lots of icons and pictures for page design use,

Response to mouse and keyboard actions, Clipboard and printer access,

Full array of mathematical, string handling, and graphics functions,

Can handle fixed and dynamic variables and control arrays,

Sequential and random access file support,

Useful debugger and error-handling facilities,

Powerful database access tools,

ActiveX support,

Package & Deployment Wizard makes distributing ones applications

and

simple

In the current , It is used to design the window that fetches the data from serial port at

a periodic interval decided by the software program.

MySQL: It is a Relational Data-Base Management System (RDBMS). MySQL stands

for My Structured Query Language. The program runs as a server providing multi-

user access to a number of data-bases. It is the software used to prepare data-base of

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the fetched data. Many web applications use MySQL, as the data-base component of a

Linux based software stack. Its popularity for use with web applications is closely tied

to the popularity of PHP, which is often combined with MySQL. Several high traffic

web sites including Flicker, Facebook, Wikipedia, Google (not the search engine)

Nokia and YouTube use MySQL, for data storage and logging of user data. Keepingthis in view and free availability of this software, it has been used as data-base for the

current work. It is available free under General Public License.

ODBC: In computing, Open Data-base Connectivity (ODBC) provides a standard

software API method for using data-base management systems (DBMS). The

designers of ODBC aimed to make it independent ofprogramming languages,

database systems, and operating systems. It works as bridge to display the data from

database. In case of MySQL, ODBC driver is installed to fetch data from it and to

display on desktop as clint. ODBC aims to provide a common API for access to

SQL1-based data-base management systems (DBMSs) such as MySQL, The

connection to the particular DBMS needs an ODBC driver and these come with the

DBMS or the ODBC driver manager or be provided separately by the DBMS

developers.

PHP: This stands for "PHP: Hypertext Preprocessor" and is a widely-used Open

Source general-purpose scripting language that is especially suited for Web

development and can be embedded into HTML. Its syntax draws upon C, Java, and

Perl, and it is easy to learn. The main goal of the language in the current project is to

allow web developers to write dynamically generated web pages quickly. Instead of

lots of commands to output HTML (as seen in C or Perl), PHP pages contain HTML

with embedded codes. The PHP code is enclosed in special start and end processing

instructions, that allows to jump into and out of "PHP mode."

What distinguishes PHP from something like client-side JavaScript is that the code is

executed on the server, generating HTML which is then sent to the client. The client

would receive the results of running that script, but would not know what the

underlying code was. Author has configured the web server to process all HTML files

with PHP.

This is the most traditional and main target field for PHP. The PHP parser (CGI or

server module), a web server and a web browser are needed to execute the present

assignment. The PHP program output can be accessed with a web browser, viewing

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the PHP page through the server. In laymans language, it is used to make the web

page dynamic; otherwise normal html page remains static. In the current work data is

continuously varying and hence display should follow the same.

Apache: Internet or intranet connectivity is possible through a well defined server.

Apache is the available medium for this. It is generally recognized as the world's most

popular Web server (HTTP server). Originally designed for Unix servers, the Apache

Web server has been ported to Windows and other network operating systems (NOS).

The name "Apache" derives from the word "patchy" that the Apache developers used

to describe early versions of their software.

The Apache Web server provides a full range of Web server features, including

CGI, SSL, and virtual domains. Apache also supports plug-in modules for

extensibility. Apache is reliable, free, and relatively easy to configure. Apache

software is distributed free by the Apache Software Foundation.

Keeping all the points in view, in current work, the author has developed a

dynamic web page on the Apache server platform, for showing the electricity

consumption, to all connected computers.

Wamp Server: It is a special purpose server that runs Apache, PHP and My SQL

simultaneously in auto configured form. In the current work, Apache is the web server,which handles browser requests and sends the information across the internet to the

browser. PHP is the programming language and creates dynamic content which in turn

is sent to Apache, which further sends the data to the browser. And finally, MySQL is

the data-base which stores the information for programs. PHP is used to access this

data-base

In the same way a great majority of websites are run by a trio of services

Apache, MySQL and PHP. It is a tried and tested trio which works phenomenally well.

Usually to gain access to all three simultaneously, a package Wamp Server is available

and has been used in this work . The WAMP Server bundle includes Apache Server,

MySQL, and PHP. WAMP stands forWindows Apache, MySQL and PHP.

It is an open source software package and available on the web.

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CHAPTER 4

Hardware and Software Implementation

4.1 Introduction

The present work was undertaken by the author with the aim to develop and implement the

scheme of a Web Enabled Automatic Electric Energy Meter that provides the metered data to

a computer server from where it may be available to every authorized person over internet.

Fig. 4.1 shows the main block diagram of the system.

Fig.4.1 Block Diagram of the Web Enabled Energy Meter

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4.2 Voltage and Current Sampling

Module 1 comprises the embedded components and is applied to monitor the voltage

and current. This is a standard Bentex make integrated circuit 7755 based module. Fig.4.2

shows its block diagram.

Fig. 4.2 Block Diagram of Module 1

Module 1, is a DSP enabled system which monitors the voltages corresponding to supply

voltage and load current. As already been discussed in sections3.1 and 3.2 of chapter 3.This

module samples the voltages

This module, based on the Atmels IC ADE7755, provides a high accuracy electrical

energy measurement system. The part specifications surpass the accuracy requirements as

quoted in the statutory standards. The only analog circuitry used in the ADE7755 is in the

ADCs and the reference circuit. All other signal processing (for example, multiplication and

filtering) is carried out in the digital domain. This approach provides superior stability and

accuracy over extremes in environmental conditions and over time.Fig.4.3 shows the

functional block diagram of IC 7755.

Fig.4.3 Functional Block Diagram of IC ADE7755

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The IC ADE7755 supplies average active power information on the low frequency

outputs, F1 and F2. These logic outputs can be used directly to drive an electromechanical

counter, and the CF logic output gives instantaneous active power information. This output is

intended to be used for calibration purposes or for interfacing to a Micro Controller Unit.

The ADE7755 includes a power supply monitoring circuit on the AVDD supply pin.

The ADE7755 remains in reset condition until the supply voltage on AVDD reaches 4 V. If the

supply falls below 4 V, the ADE7755 resets and no pulse is issued on F 1, F2, and CF. Internal

phase matching circuitry ensures that the voltage and current channels are phase matched

whether the HPF in Channel 1 is on or off. An internal no load threshold ensures that the

ADE7755 does not exhibit any creep when there is no load. The easiest way to interface the

ADE7755 to a microcontroller is to use the high frequency output CF with the output

frequency scaling set to 2048 F1, F2. This is done by setting SCF = 0 and S0 = S1 = 1 [21].

With full-scale ac signals on the analog inputs, the output frequency on CF is approximately

3.6 kHz. These pulses are taken to an opto-coupler and then applied to microcontroller. Fig.

4.4 shows the embedded circuit of module 1 based on IC 7755.

Fig. 4.4 Embeded Circuit of Module 1, based on IC 7750

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4.3 Microcontroller Selection

The Web Enabled Automatic Electrical Energy Meter has been implemented using

Atmels microcontroller AT89S52. The AT89S52 is a low-power, high-performance CMOS

8-bit microcontroller with 8K bytes of in-system programmable Flash memory. The on-chip

Flash allows the program memory to be reprogrammed in-system or by a conventional non-

volatile memory pro-grammer. By combining a versatile 8-bit CPU with in-system

programmable Flash on a monolithic chip, the Atmel AT89S52 has become a powerful

microcontroller which provides a highly-flexible and cost-effective solution to many

embedded control applications. Fig.4.5 shows the simple architecture of this microcontroller

IC.

Fig 4.5 Architecture of ATMELs Microcontroller AT 89S52

The AT89S52 provides the following standard features:

8K bytes of In-System Programmable (ISP) Flash Memory,

256 bytes of RAM,

32 I/O lines, distributed in four ports,

Watchdog timer,

Two data pointers,

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Three 16-bit timer/counters,

A six-vector two-level interrupt architecture,

A full duplex serial UART Serial Channel port, on-chip oscillator, Clock circuitry.

4.0V to 5.5V Operating Range

Compatible with MCS-51 Products

Fully Static Operation: 0 Hz to 33 MHz

With the availability in the Indian market at economic rate and build in with these

features along with ease of programming made the microcontroller AT 89S52 the first choice

to be used in Web Enabled Automatic Electric Energy Meter. Fig.4.6 shows the internal

architecture of microcontroller AT 89 S 52.

Fig. 4.6 Internal Archietecture of Microcontroller

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4.4 Microcontroller Pin Connections

Microcontroller receives the signal from the terminal marked CF in IC 7755 through opto-

coupler in power module. Frequency of the signal is proportional to average power consumed.

This input is received at the pin no.12 which is an active low interrupt under port 3 of

microcontroller. Fig 4.7 shows the various input and out put connections of microcontroller

AT 89S52.

Fig.4.7 Pin Connections of Microcontroller AT 89S52

Pin 26 to 28 and 32 to 39 are connected with the LCD display board.These pins constitute the

Port 0 and partly port 3. Pin 21 and 22 are connected with the external EEPROM for

integration of the pulse data received from the power module 1. Pin 6 to 9 are assigned for In

System Programming (ISP) in serial mode. Crystal of 11.0592 MHz.is connected between

Pins 18 and 19, which are specifically assigned this function. Pin 40 and Pin 31, are connected

to the supply and pin 20 is grounded.

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4.5 External Code Memory

External memory exists off chip in the form of EEPROM. This is a serial in out

memory. Serial memory devices offer significant advantages over parallel devices in applica-

tions where lower data transfer rates are acceptable. In addition to requiring less board space,

serial devices allow microcontroller I/O pins to be conserved. This is especially valuable

when adding external memory to low-pin count microcontrollers such as the Atmel AT89S52

and AT89C4051. External memory is only of 2 KB and address bits A0, A1 and A2 are kept

high. Pin diagram of IC 2402 is shown in Fig. 4.8.

Fig.4.9 shows the connections of the external memory chip with the microcontroller.

Two wire serial EEPROM IC 2402 has been used in the current assignment, This EEPROM is

Internally organized with 256 x 8 bits (2k), in 32 pages of 8 bytes each, the 2K requires an 8-

bit data word address for random word addressing.

Fig. 4.8 Pin Diagram of IC 2402

Fig.4.9. External Memory Connection with Microcontroller

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4.6 Transmitter/ Receiver Hardware

Microcontroller AT 89S52 supplies the data of energy consumption, to the computer

through its serial port which is based upon the RS 232 standard. Matching of the

microcontroller to RS 232 is done through another IC HIN 232. The HIN232 family of RS-

232 transmitters/receivers interface circuits meet all RS-232E specifications, and are

particularly suited for those applications where 12V is not available. They require a single

+5V power supply and feature onboard charge pump voltage converters which generate +10V

and -10V supplies from the 5V supply.

This family of devices offer a wide variety of RS-232 transmitter/receiver combinations to

accommodate various applications efficiently hence has been preferred for developing the

hardware. The drivers with this device feature true TTL/CMOS input compatibility, The

receivers can handle up to 30V, and have a 3 to 7 k input impedance. The receivers alsofeature hysteresis to greatly improve noise rejection. The Fig. 4.10 shows the pin

configuration of IC HIN 232 CP

Fig.4.10 Pin Configuration of IC HIN 232 CP

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4.7 Liquid Crystal Display(LCD) Panel

Microcontroller also drive an LCD panel which remains available at the users

premises so that consumption of electrical energy may be visible at the measuring end also.

Sunrom make LCD panel has been used for this purpose.This is a high quality 16 character

by 2 line intelligent display module, with back lighting. It works very well with AT 89S52

microcontroller. It has the following features:

16 Characters x 2 Lines

5x7 Dot Matrix Character + Cursor

LCD Controller/driver Built-In

4-bit or 8-bit MPU Interface

Standard Type

Works with almost any Microcontroller

Fig.4.11 shows the LCD panel used in the circuit.

Fig. 4.11 LCD Panel

4.8 Complete Hardware Implementation

In case of hardware microcontroller is the heart of the work. It takes the pulses from the

power module and counts them to convert into the equivalent energy value. This energy value

is displayed in the LCD panel. At power on, microcontroller displays the kWh reading stored

in EEPROM IC.

Working of the microcontroller AT 89 S 52 is depicted in flow-chart shown in Fig.4.12.

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Fig. 4.12 Flow chart of Microcontroller Operation

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EEPROM IC 2402 maintains the kWh data in nonvolatile mode so that reading always

remain there in case of power failure also. Module 1, IC 7755 keeps the track of voltage,

current and corresponding power. In proportional to the average power pulses are made

available at its pin CF and which through isolation of an optocoupler sends these pulses at the

pin 12 marked as INT0 of Microcontroller AT 89S52. The same pin can also be used for other

interrupts also hence microcontroller checks for proper signal of pulse count. In case of power

pulses counting starts at the rate of total 3600 pulses per kWh. As soon as pulse count reaches

3599 next pulse resets the pulse display and microcontroller increments the EEPROM reading

of kWh by 1 and the cycle repeats.

Display of pulse count and kWh readings is on the same panel but both are controlled

separately. EEPROM IC 2402 is available for integration of energy as well as maintaining the

data secure in case of power failure.

4.9 Supporting Components

Complete circuit require some supporting components also for its working. These

components are as follows:

Miniature Transformer It is a 6-0-6 volts, 300 mA, centre tap transformer with 230

V in put winding. This provides the electrical power for the functioning of the

complete assembly. In case of working units this consumption would also be taken

into account.

Voltage Regulator IC 7805 is the common three legs IC used for the regulation of the

dc voltage before supply is made available to the different integrated circuits. This has

rated for a current up to 1 amp. In the present case total demand is limited within

200mA only.

Terminal Block It is the location where supply and load conductors are connected

with the meter. It is made of hardened fireproof plastic and chrome plated copper

terminals are moulded in it. All the connections are secured by the brass terminal and

screws for least resistance contacts.

Crystal Clock quartz crystal in metal can is also mounted with the microcontroller IC

to maintain the constant frequency of the microcontroller. This crystal has its

resonance frequency equal to 11.0592 MHz.

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Current Transformer Current monitoring is done with the use of a current

transformer (CT) shown in Fig. 4.13. This CT has 1000 turns in the secondary winding

and rated for 10 A of the current.

Fig. 4.13 Terminal Block and Current Transformer

Miscellaneous Items Various miscellaneous items such as indicating LEDs, resistors,

Capacitors, hook up wires, bakelite printed circuited board etc. are also included in the

final prototype working model of the present system. Complete circuit is developed on

hardboard and main components are tied by the metal screws.

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4.10 Complete Assembly of the Circuit

Fig. 4.14 shows the photograph of actual prototype assembly of the Web Enabled Automatic

Electric Energy Meter. On the board, microcontroller IC, module-1 based on IC 7755,

external EEPROM IC 2402, Serial port interface IC HIN 232, and LCD panel are mounted

with all the electrical connections.

Fig.4.14 Complete Assembly of Web Enabled Electrical Energy Meter without PC

Complete circuit is powered by a miniature center tap transformer, full-wave rectifier

with filter capacitors and 5 Volts regulator. This circuit delivers a current 300 mA maximum,

which is sufficient for this circuit. Plastic moulded connectors are provided for power

connections from supply and load sides. Current measurement has been done using a

miniature current transformer of 1000 : 1 ratio.

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4.11 Software Implementation

Electronic circuit as fabricated for this Web Enabled Automatic Electric Energy Meter

requires various software programs to run and perform the desired operation. Following

software were used for this purpose:

C / Assembly language compatible to 8051 series of microcontrollers,

Visual Basic Studio for data recorder set up as shown in Fig.4.15

Wamp Server comprising Apache, PHP and My SQL

Open Data Base Connectivity (ODBC) for bridging between data recorder and

database in My SQL.

Fig.4.15 Visual Basic Data Recorder Window

4.12 Web Page

A dynamic web page is prepared with the PHP software available in Wamp Server.

The same server also contains the Apache which floats this dynamic page for internet or

intranet.

Two web pages are prepared to show the following data on the net:

Hourly data page : Updates every minute to the data for one hour, as shown in

Fig.4.16

Daily data page: After every hour this page is updated and it keeps the data for

one year as shown in Fig. 4.17

Web page in background keeps the users identity, password and payment

made to utility.

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Fig.4.16 Hourly data page

Fig.4.17. Daily data page

4.13 System Operation

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Working of the system requires installation of all the software in main server PC.

These software are ODBC, VB studio-6, My SQL, Apache, and PHP. Although last three are

included in configured manner with Wamp Server itself. As per the fig. 4.18 connections from

the pins 10 and 11 along with the ground reaches to serial port of the PC through transmitter/

Receiver IC HIN 232.

Fig.4.18 Layout and connections of the complete circuit

All the electrical energy consumption is interpreted by the microcontroller and displayed at

the local LCD display. Corresponding data is also send to the serial port of the PC, where

whole of the data is fed to data-base MySQL. This data will remain for complete one year.

Frequency of data collection is set by the software as one reading per minute whereas

hardware is so tuned that 3600 pulses are generated for each one kilowatt-hour. Energy

consumption data is collected at the buffer of the serial port from where it is collected by the

software data- recorder. Data-storage-rate may be different from the one minute software rate

of data reading by the PC, therefore to avoid any dispute PC software always collects the

latest data available at the serial port buffer.

4.14 Complete Circuit Diagram

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Fig. 4.19 Complete Circuit Diagram

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CHAPTER 5

Results and Discussions

5.1 ResultsDesign and development of solid-state single-phase web enabled electric energy meter

was successfully completed. The electric energy was captured with integrated circuit AD7750

based module and processed by Atmels microcontroller AD 89S52. Instantaneous reading is

shown on the LCD panel where as hourly and daily log is maintained on the computer data-

base. This log on the PC will remain maintained up to one year and updated subsequently.

Rating of the system is designed for 2 kW load and standard pulses produced for the

calibration and for microcontroller are 3600 per KWH.It is clear from the databases created by

the prototype, that reading for energy consumption is available up to fourth place of the

decimal. With a load of as low as 60 W and for higher load of 1000 W, meter has recorded the

correct consumption reading and maintained the record.Fig.4.20 shows the section of the data-

base.

Fig. 4.20 Section of the data-base created by the proto-type developed in the work

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5.2 Discussions

Interfacing between the hardware and the PC is through serial port, whereas other

ports are also available in the PC. Serial port in smaller PCs such as laptops, is now phasing

out, even than serial port has been given priority over the others in the present work.

Serial port is based on the protocol defined by EIA specification RS 232 and has

numerous feature which suits the power level jobs. It has longer connectivity up to 100 feet

where as USB has only 16 feet. Speed is slower than the USB but it is compensated by its

cost.

Its Speed is around 20 kbps when used alone and up to 115 kbps maximum when used

with other external drivers. This speed is more than required to transfer the electric data from

metering module to the PC.

RS 232 also supports the asynchronous mode of data transmission; therefore UART ofthe microcontroller suits the serial port with minimum number of wires. It also makes this

system independent of the particular computer and thus any unit can be used by any computer.

In microcontroller crystal frequency 11.0592 MHz, is also within the range of UART

bit-rate frequency. In a PC, standard UART clock frequency is 1.8432 MHz, with respect to

this the bit rate would be 1.8432MHz / 16 = 1, 15,200 Hz. In microcontroller with crystal

frequency of 11.0592 MHz, hardware timer runs at 11.0592/12 = 921600 Hz and this allows

the bit rate of 921600 / 16 = 57,600 Hz only which is compatible with computers top rate.

Maintenance of data records for one year needs memory space of around 1.2 MB per

consumer. This figure is not enormously high and could be accepted.

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Conclusion

Scenario in power sector prompted the author to undertake the current project and a

prototype of Web enabled Automatic Electrical Energy Meter has been designed and

fabricated with indigenously available components. The meter has been tested successfully.

Implementation of microcontroller based energy meter can read the energy consumption successfully

within permissible limits of the error. It is found to be most suitable for the present day need, and it is

inevitable that within one decade, this would be the only option left with the electricity utility

companies and the consumers. Conclusions out of the current work are summarized below:

A web page is designed on which details of the kWh consumed are uploaded.

Consumption rate on one minute basis is also uploaded on the page. This

minute detail is maintained for every one hour.

Accumulated data for one hour is transferred to daily data log successfully and

record is maintained.

It is estimated that per consumer around 1.2 MB memory space would be

required for maintenance of the yearly record.

.

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Future Scope

This work is suitable for the domestic requirement of electricity in typical Indian

houses..Even then there exists scope of improvement. The future scope points are summarized

below:

There is scope to develop an integrated system in which power measurement and

processing should be in one module only. This can be achieved using FPGA or FPAA

technology. This will make the system more compact and modular.

This system has scope to provide more channels to record frequency, power factor and

reactive power. This can also be developed for three phase system also.

In the current work the author has used a PC to connect to the network. But there is

scope to make the modular power measuring apparatus directly connected to the cyber

space. For this purpose each device should be allotted an individual dynamic IP code.

Such system would directly link itself with the server situated remotely. Connection

with the remote server may be wired or wireless using broad band.

As far as software part is concerned a lot of scope exists in developing a compact

package to run the entire work and different isolated software may not be required. In

current project compatibility among different software packages and their versions

created lot of trouble.

In the current system data transfer is only one way, but in future this may be made two

way so that server can control the meter. In such a case, power control can be

implemented from the server end also. Consumer may also be alerted for some fault

from the consumer end.

There is further scope of enhancing this system to become a part of the network in

which issuance of the electricity bills and their payments would be on-line. This is not

an impossible preposition because all the banks are already on-line, meters can also be

on-line. In other words concept of prepaid meters may also be realized.

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References and Bibliography

1 Stebbins Wayne L New concepts in Electrical Metering for Energy Management IEEE

Transaction on Industry Application, Vol. 1A-22, No. 2 March/April 1986.

2 Gambhir Ajay Improving Billing and Load Management Communications ForEnergy Meter Manufacturers and Service Providers for Analog Devices, Inc.

September 2003.

3 Reaz M.I., Rahman M.S., Mohd-Yasin F, Sulaman M.S., Choong F., Development of

an efficient and flexible Algorithm for Implementing A Digital Household Energy

Meter: An FPGA Approach, 3rd International Conference on Electrical & Computer

Engineering, ICECE-2004, 28-30 December 2004, Dhaka, Bangladesh.

4 Application note, Atmel, AVR465: Single phase Power/Energy Meter with Temper

Detection, Source, available at Atmels web site www.atmel.com/literature.

5 Nagarju M, Praveen Kumar T., Networked Electronic Energy Meter with Power Quality

Analysis, Signion Systems Ltd., Hyderabad, IEEE Transactions on electric power, available

on IEEE Xplore, Power Quality 98, June, 18, 98, pages 45 - 57.

6 Installation and Operation Manual: Web enabled meter, WEM MX, Energy Tracking,

available at the companys sitewww.energytracking.com, updated Aug,19, 2008.

7 Paranhos I., Lbano F, Melchiors J, Mano O, Roenick A., Power Energy Meter in a low

cost Hardware/ Software, IEEE symposium on Power Electronics, volume 3, July, 9-13,

2006, pages 1712-1715.

8 Coca Eugen, A new Energy meter interface using internet communications, 7 th International

Conference on Development and Application Systems, Suceava, Romania, May 27-29, 2004;

9 Markow John, Microcontroller based Energy Metering using the AD 7755, Analog Dialogue

33-9 (1999): Technical specification of the IC AD 7755.

10 Specification sheet of IC ADE 7754, Multifunction Polyphase Energy Metering IC with Serial

port interface. Issued by Analog Devices Inc, revised on Jan, 2008.

11 Atmel 8-bit AVR Microcontrollers based AVR465: Single-Phase Power/Energy meter with

Tamper Detection, specification manual revised on Apr,2007.

12 Loss P.A.V, Lamego M.M, Sousa G.C.D. and Vieira J.L.F A Single Phase Microcontroller

based Energy Meter, IEEE Instrumentation and Measurement Technology Conference, St.

Paul, Minessota, USA, May, 18-21, pp 797-800.

13 Chavan Santosh S, Jayaprakash S. and Kumar Jagdeesh V, An Open Standard Protocol for

Networking of Energy Meters, IEEE Transactions no.0885-8977 on Power Delivery, Vol 23,

No.4, October, 2008.

50
http://www.energytracking.com/http://www.energytracking.com/http://www.energytracking.com/


51/51

14 Ayurzana Odgerel et al. Development of Telemetering system of water supply using RF

module and TCP/IP Socket programme Paper presented in the SICE-ICASE International

Joint Conference, Oct, 18-21, 2006 Busan Korea.

15 Cao Litting, Tian Jingwen and Liu Yanxia, Remote Wireless Automatic Meter Reading

System Based on Wireless Mesh Networks and Embedded Technology, 5th IEEE

International Symposium on Embedded Computing, DOI 10.1109/SEC.2008.57;Oct, 6 -8,

2008, pp 192-197.

16 Cao Liting, Tian Jingwen and Zhang Dahang, Networked Remote Meter-Reading System

Based on Wireless Communication Technology Proceedings of the 2006 IEEE International

Conference on Information Acquestion, Weihai, Shandong, China, August 20-23, 2006, pp

172 176.

17 Krukowski Artur and Kale Izzet, Simulink/MAtlab-to-VHDL Route for Full-Custom/FPGA

Rapid Prototyping of DSP Algorithm, Matlab DSP Conference(DSP99), Tempere, Finland,

November, 16-17, 1999.

18 Naphade S.P. The TATA power Co. Ltd. Mumbai, Automatic Meter Reading- Cost

Reduction Techniques, Note available on internet.

19 Doraswami Anand, Associate Editor, Energy for Sustainable Development, A Case for

electronic electricity meters in India, Energy for Sustainable Development, Volume II No.2

July, 1995.

20 Specification sheet [20] provided by Atmel for 8-Bit Microcontroller no. AT89S52

with 8KB in system Programmable Flash memory gives the methods to develop thecircuit as per the requirement.

21 Specification sheet [21] provided by Atmel for Energy metering IC ADE 7755.

22 Axelson Jan, Serial Port Complete, Penram Int. Publishing(India) Pvt. Ltd.

.000.

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