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Transcript of 6 Introduction
WIRELESS DISTRIBUTED LOAD SHEDDIND MANAGEMENT SYSTEM
CHAPTER-1
INTRODUCTION
Load shedding is a process in which electric power is cutoff on
certain lines of power transformers when the demand approaches the system
capacity. Load shedding is particularly important in isolated systems since
there is no interconnected supply of power if the demand exceeds the power
rating of the transformers. Typically load shedding is done by supervisory
and monitoring systems such as supervisory control and data acquisition
systems known as SCADA systems which continuously monitor vital
parameters of the power system. SCADA systems usually shed the
appropriate power load keeping a well-balanced system and at the same time
maintaining reasonable customer satisfaction.
Systems located in a hot climate zone, such as the emirates of
Sharjah and Dubai of the United Arab Emirates, have many remotely-
distributed transformers throughout the coverage area. During hot days, the
peak power consumption is significantly higher than normal days. Even
though the power grid is designed to handle such peak loads, it is possible
that spurious excessive demand may cause power shutdown.
1.1.OBJECTIVE
Wireless –Distributed Load-Shedding Management System which
is designed to handle remotely distributed transformers which is located in
hot climatic zone, lacking SCADA system using GSM technique. The
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proposed system is used to protect the distributed transformers and
proactively involves users in the shedding process.
1.2. SYSTEM DESIGN
The designed system called Wireless Distributed Load-Shedding
Management System consists of three main modules. The DCM, the
wireless communication module, and the CPM. The DCM is installed at the
physical location of the transformer site. It consists of a system status
monitor, that continuously records and processes current on each feeder. The
wireless communication module consists of a GPRS modem that sends SMS
messages over the GSM messages over the GSM network from the control
center to the transformer site. This module is the communication backbone
of the proposed system. The CPM processes the data, collected and fed-back
by the GPRS modem at the transformer site, and sends control signals
depending on the situations such as faults and overloads, or by special
requests from authorized employees.
1.3 MODES OF OPERATION
The system should be configured to operate in two different
modes: standard and caution modes.
In the standard mode the system sensors measure the current per
feeder, oil temperature and the location temperature of the transformer every
hour and send an end-of-day SMS (type-C) to the control center server.
Type-C SMS contains transformer number, average current readings on all
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feeders, and oil temperature readings of the transformer. The purpose of
these end-of-day SMS messages is to increase the reliability of data
collection and to frequently update the database. Physical fault at the
transformers site, a type-B SMS message is sent to the server.
WDL-SMS will operate in caution mode if current loads on any
of the transformer feeders exceed a specified preset values. A type-A
overload SMS message will be sent to the server. The control center server
then searches for respective consumers on that particular feeder inside its
database. The server initiates “Overload” SMS messages to these consumers,
asking them to reduce their power consumption. If the load is not reduced
within a certain period of time called grace period, the control center asks
the DCM at the transformers site to disconnect one or more feeders by
sending Disconnect SMS. The system will also operated in caution mode if
the oil and/or location temperature of the transformer exceed some preset
threshold values.
1.4 COMMUNICATION PROTOCOL
As the systems modules need to interact with each others during
system operation, several communications messages are used between
modules. These messages include microcontroller-to-server, server-to-
microcontroller, and server-to-consumer messages.
1.4.1 Microcontroller-to-server Messages
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Microcontroller messages are mainly used in reporting data from
the DCM module to the server of the CPM module. Three types of messages
are used :
Alarm Message
Update Message
Fault Message
Send-on-Request Message
1.4.2 Server-to-microcontroller Messages
The server communicates with the microcontroller using three
different types of message: Request, Disconnect and Connect.
Request Message:
Whenever the current reading of the transformer parameters are
required by the utility site, a message is sent to the microcontroller
Disconnect Message: This message is sent to the microcontroller if the feeders are to
be disconnected by the company.
Connect Message:
This message is sent to the microcontroller if the feeders are to
be reconnected by the company.
1.4.3 Server-to-consumer Messages
In the event of excess power consumption, the consumer
might receive the following alert message “Please reduce your power
consumption or else you might suffer power loss. Thank you”.This message
consists of 65 ASCII characters totaling 455 bits per SMS message per
alerted customer.
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CHAPTER-2
BLOCK DIAGRAM DESCRIPTION
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Fig2.1: Block diagram
2.1. INTRODUCTION
The block diagram comprises of ATMEGA 328, GSM modem,
Relay, Interfacing Device(RS 232 Serial port) and Temperature Sensor.
Each device in each block has its own duties and functions.
2.2. ATMEGA 328
Micro controller (ATMEGA 328) is the main heart of our system. It
operates in 5v supply. All the devices is being connected with
microcontroller including Temperature sensor, Relay, GSM modem .The
operating conditions were programmed and been loaded in the
microcontroller. It will work according to the operating conditions. The
relay will be turn on/off according to the instructions that are given by the
microcontroller. The GSM modem is connected through interfacing devices
known as RS 232 serial port.
2.3. GSM MODEM
The GSM modem is being interfaced with microcontroller
through RS 232 serial port. It will send early warning messages to the
customer for reducing the power consumption. A GSM modem can be a
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dedicated modem device with a serial, USB or Bluetooth connection, or it
may be a mobile phone that provides GSM modem capabilities. A GSM
modem exposes an interface that allows applications such as Now SMS to
send and receive messages over the modem interface.
2.4. TEMPERATURE SENSOR (LM35)
Temperature sensor will sense atmospheric temperature. The
temperature limit can be set in the program itself. Here LM35 is used as the
Temperature sensor. If the temperature exceed the fixed value it will send
message to the Electricity Board.
2.5. RELAY
Relay is an electrical switch that opens and closes under the
control of another electrical circuit. In the original form, the switch is
operated as an electromagnet to open or close one or more sets of contacts.
A Relay is able to control an output circuit of higher power than the input
circuit, it can be considered to be, in a broad sense, a form of an electrical
amplifier. The relay will turned off if any disturbance occur in the system.
2.6. RS 232 INTERFACE
It is a standard serial interfacing device used for interfacing PIC
and GSM modem. It will work with the voltages of -15V to +15V for high
and low. The voltage for logic 1 ranges from -3V to -12V and for logic 0 it
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ranges from +3V to +12V.Modern low-power logic operates in the range of
0V….+3.3V or even lower.
CHAPTER-3
HARDWARE DESCRIPTIONS
The main hardware equipments which were employed in our
project are Micro controller (ATMEGA 328), LCD Display, GSM modem,
Current Transformers (CT’s), Relays, Feeders, Loads, Temperature Sensor.
Each of them is been briefly explained one by one as follow:
3.1.ATMEGA 328
Fig.2 .ATMEGA 328
Micro controller (ATMEGA 328) is the main heart of our system. It
operates in 5v supply. All the devices is being connected with
microcontroller including Temperature sensor, Relay, GSM modem .The
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operating conditions were programmed and been loaded in the
microcontroller. It will work according to the operating conditions. The
relay will be turn on/off according to the instructions that are given by the
microcontroller. The GSM modem is connected through interfacing devices
known as RS 232 serial port.
Fig. PINOUT DIAGRAM
3.2.PIN DESCRIPTIONS
Write something here regarding the pin details below & start all
paragraph with a space
3.2.1.VCC
Digital supply voltage.
3.2.2 GND
Ground.
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3.2.3 Port B (PB7:0) XTAL1/XTAL2/TOSC1/TOSC2
…………Port B is an 8-bit bi-directional I/O port with internal pull-up
resistors (selected for each bit). The Port B output buffers have symmetrical
drive characteristics with both high sink and source capability. As inputs,
Port B pins that are externally pulled low will source current if the pull-up
resistors are activated. The Port B pins are tri-stated when a reset condition
becomes active, even if the clock is not running.
Depending on the clock selection fuse settings, PB6 can be used as input to
the inverting Oscillator amplifier and input to the internal clock operating
circuit. Depending on the clock selection fuse settings, PB7 can be used as
output from the inverting Oscillator amplifier. If the Internal Calibrated RC
Oscillator is used as chip clock source, PB7...6 is used as TOSC2...1 input
for the Asynchronous Timer/Counter2 if the AS2 bit in ASSR is set.
3.2.4 Port C (PC5:0)
……….Port C is a 7-bit bi-directional I/O port with internal pull-up resistors
(selected for each bit). The PC5...0 output buffers have symmetrical drive
characteristics with both high sink and source capability. As inputs, Port C
pins that are externally pulled low will source current if the pull-up resistors
are activated. The Port C pins are tri-stated when a reset condition becomes
active, even if the clock is not running.
3.2.5 PC6/RESET
If the RSTDISBL Fuse is programmed, PC6 is used as an I/O pin. Note that
the electrical characteristics of PC6 differ from those of the other pins of
Port C. If the RSTDISBL Fuse is unprogrammed, PC6 is used as a Reset
input. A low level on this pin for longer than the minimum pulse length will
generate a Reset, even if the clock is not running.
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3.2.6 Port D (PD7:0)
Port D is an 8-bit bi-directional I/O port with internal pull-up resistors
(selected for each bit). The Port D output buffers have symmetrical drive
characteristics with both high sink and source capability. As inputs, Port D
pins that are externally pulled low will source current if the pull-up resistors
are activated. The Port D pins are tri-stated when a reset condition becomes
active, even if the clock is not running.
3.2.7 AVCC
AVCC is the supply voltage pin for the A/D Converter, PC3:0, and ADC7:6.
It should be externally connected to VCC, even if the ADC is not used. If
the ADC is used, it should be connected to VCC through a low-pass filter.
Note thatPC6...4 use digital supply voltage, VCC.
3.3. LCD MODULE
Fig.3.LCD Module
Don’t under line
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A liquid crystal display (LCD) is a thin, flat electronic visual
display that uses the light modulating properties of liquid crystals (LCs).
LCs does not emit light directly.
They are used in a wide range of applications, including
computer monitors, television, instrument panels, aircraft cockpit displays,
signage, etc. They are common in consumer devices such as video players,
gaming devices, clocks, watches, calculators, and telephones. LCDs have
displaced cathode ray tube (CRT) displays in most applications. They are
usually more compact, lightweight, portable, less expensive, more reliable,
and easier on the eyes] They are available in a wider range of screen sizes
than CRT and plasma displays, and since they do not use phosphors, they
cannot suffer image burn-in.
LCDs are more energy efficient and offer safer disposal than
CRTs. Its low electrical power consumption enables it to be used in battery-
powered electronic equipment. It is an electronically-modulated optical
device made up of any number of pixels filled with liquid crystals and
arrayed in front of a light source (backlight) or reflector to produce images
in colour or monochrome.
3.4.GSM MODEM
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Fig.4.GSM Modem
A GSM modem is a specialized modem which accepts SIM
card and operates over a subscription to a mobile operator, just like a mobile
phone. A GSM modem has a serial connection. A GSM modem exposes an
interface that allows applications such as to send and receive messages over
the modem interface. A GSM modem is a wireless modem that works with
wireless network. Computers use AT commands (Attention commands) to
control modems. The number of SMS that can be processed by a GSM per
minute is about 6-10. A GSM modem is a wireless modem that works with a
GSM wireless network. A wireless modem behaves like a dial-up modem.
The main difference between them is that a dial-up modem sends and
receives data through a fixed telephone line while a wireless modem sends
and receives data through radio waves.
GSM modems can be a quick and efficient way to get started
with SMS, because a special subscription to an SMS service provider is not
required. The mobile operator charges for this message sending and
receiving as if it was performed directly on a mobile phone.
3.4.1. GSM MODEM FEATURES
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Quad Band GSM/GPRS
850/900/1800/1900Mhz
GPRS multi-slot class 10/8
GPRS Mobile station class B
Compliant to GSM Phase 2/2+
Class 4 (2W@850/900Mhz)
Class 1(1W@1800/1900Mhz)
Control via AT commands (GSM 07.07, 07.05 and enhanced AT
commands)
3.4.2. INTERFACES
RS-232 through D-TYPE 9 pin connector, Serial port baud rate
adjustable 1200 to115200 bps (9600 default)
Stereo connector for MIC & SPK
Power supply through DC socket
SMA antenna connector
Push switch type SIM holder
LED status of GSM / GPRS module
3.3.3. AT COMMANDS
Communication with the GSM modem is by using AT
commands. To perform these tasks, a GSM modem must support an
"extended AT command set" for sending/receiving SMS messages.
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Commands for Reading and Sending SMS is as follows
1. Set SMS mode
Command : AT+CMGF=1
2. Send SMS
Command : AT+CMGS=<”number”><Crriagereturn>(new line)
(>)<matter> <ctrl+z>
3. Read SMS
Command : AT+CMGR=<location>
3.4.4. SIM305/SIM345 (GSM MODEM)
The SIM305/345 is a complete Dual-band/Quad-band
GSM/GPRS solution in a compact plug-in module. Featuring an industry-
standard interface, the SIM305/345 delivers GSM/GPRS
50/900/1800/1900MHz performance for Voice, SMS, Data, and Fax in a
small form factor and with low power consumption.
The leading features of SIM305/345 make it ideal for M2M applications,
such as AMR, POS, Security, AVL etc.
3.4.4.1. General features
Dual-Band GSM/GPRS 900/1800MHz or Quad-Band GSM/GPRS
850/900/1800/1900MHz
GPRS multi-slot class 10
GPRS mobile station class B
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Compliant to GSM phase 2/2+
Class 4 (2 W @ 850/900MHz)
Class 1 (1 W @ 1800/1900MHz)
Dimension: 58mm x 32mmx 3.9 mm
Weight: <12g
SIM application toolkit
Supply voltage range 3.4 ... 4.5 V
Low power consumption
Normal operation temperature: -30°C to +80°C
Restricted operation temperature: -40°C to -30°C and +80°C to +85°C
Storage temperature: -45°C to +90°C
3.4.4.2. Specifications for SMS via GSM / GPRS
Point-to-point MO and MT
SMS cell broadcast
Text and PDU mode
3.5. CURRENT TRANSFORMER
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Fig.5.Different Types of Current Transformers
Here two Current Transformers are used to measure the
current across feeders. It will out the corresponding voltage values by the
principle of Electromagnetic Induction. The phase of each feeders were
passed through the core of CT’s. It is rated to be 5A. A bridge circuit is
necessary for connecting the Current Transformers.
It is not possible to use line current directly for
measurement and relaying purpose due to its high value and insulation
problem. CURRENT TRANSFORMER which is widely known as 'CT ' is a
piece of electrical equipment which converts line current (primary current)
in to small standard current values which are suitable for the devices to
which it is connected e.g. measuring instruments, meters, protection relays.
3.5.1. BASIC FUNCTIONS OF CT’s
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To reduce line current to a value which is suitable for standard
measuring instruments, relays etc.
To isolate the measuring instruments, meters, relays etc. from line
voltage of an installation.
To protect measuring instruments against short circuit currents.
To sense abnormalities in current and give current signals to
protective relays to isolate the defective system
Ring type (or rectangular type) CTs are normally preferred
over other types of CTs. because they are simple in construction,
mechanically stronger and cheaper. In a ring type/bar primary type CTs the
working ampere-turns are determined by the primary current and therefore
necessarily, the accuracy that can be offered with these CTs becomes
progressively inferior as the rated primary current decreases.'-If higher
accuracy and burdens are required for CTs of low primary current wound
types CTs are used.
3.6. MAX 232 LEVEL CONVERTERS
.
Fig.6. MAX 232 pin Fig.7.MAX 232 Interface
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For interfacing PIC and GSM modem Serial RS-232
communication is used. It works with voltages 15V to +15V for high and
low. On the other hand, TTL logic operates between 0V and +5V . Modern
low power consumption logic operates in the range of 0V and +3.3V or even
lower.
Thus the RS-232 signal levels are far too high TTL electronics,
and the negative RS-232 voltage for high can’t be handled at all by computer
logic. To receive serial data from an RS-232 interface the voltage has to be
reduced also the low and high voltage level has to be inverted.
Table-1
This module is primary of interest for people building their own
electronics with an RS-232 interface. Serial RS-232 communication works
with voltages (-15V ... -3V for high ) and +3V ... +15V for low) which are
not compatible with normal computer logic voltages. On the other hand,
classic TTL computer logic operates between 0V ... +5V (roughly 0V ...
+0.8V for low, +2V ... +5V for high). Modern low-power logic operates in
the range of 0V ... +3.3V or even lower.
So, the maximum RS-232 signal levels are far too high for
computer logic electronics, and the negative RS-232 voltage for high can't
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RS-232 TTL Logic
-15V … -3V +2V … +5V High
+3V … +15V 0V … +0.8V Low
WIRELESS DISTRIBUTED LOAD SHEDDIND MANAGEMENT SYSTEM
be grokked at all by computer logic. Therefore, to receive serial data from
an RS-232 interface the voltage has to be reduced, and the low and high
voltage level inverted. In the other direction (sending data from some logic
over RS-232) the low logic voltage has to be "bumped up", and a negative
voltage has to be generated, too.
RS-232 TTL Logic
-----------------------------------------------
-15V ... -3V <-> +2V ... +5V <-> high
+3V ... +15V <-> 0V ... +0.8V <-> low
All this can be done with conventional analog electronics,
e.g. a particular power supply and a couple of transistors or the once
popular 1488 (transmitter) and 1489 (receiver) ICs. However, since more
than a decade it has become standard in amateur electronics to do the
necessary signal level conversion with an integrated circuit (IC) from the
MAX232 family (typically a MAX232A or some clone). In fact, it is hard
to find some RS-232 circuitry in amateur electronics without a MAX232A
or some clone.
The MAX232 from Maxim was the first IC which in one
package contains the necessary drivers (two) and receivers (also two), to
adapt the RS-232 signal voltage levels to TTL logic. It became popular,
because it just needs one voltage (+5V) and generates the necessary RS-
232 voltage levels (approx. -10V and +10V) internally. This greatly
simplified the design of circuitry. Circuitry designers no longer need to
design and build a power supply with three voltages (e.g. -12V, +5V, and
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+12V), but could just provide one +5V power supply, e.g. with the help of
a simple 78x05 voltage converter.
3.7. RELAY
Fig.8.Relay
Here three relays are used, two for two feeders and one for
Temperature sensor. A relay is a simple electromechanical switch made up
of an electromagnet and a set of contacts. Relays are found hidden in all
sorts of devices. In fact, some of the first computers ever built used relays to
implement Boolean gates .
A simple electromagnetic relay consists of a coil of wire
surrounding a soft iron core , an iron yoke which provides a low reluctance
path for magnetic flux, a movable iron armature, and one or more sets of
contacts (there are two in the relay pictured). When an electric current is
passed through the coil it generates a magnetic field that attracts the
armature and the consequent movement of the movable contact(s) either
makes or breaks (depending upon construction) a connection with a fixed
contact. If the set of contacts was closed when the relay was de-energized,
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then the movement opens the contacts and breaks the connection, and vice
versa if the contacts were open.
Relays are used to and for:
Control a high-voltage circuit with a low-voltage signal, as in some
types of modems or audio amplifiers,
Control a high-current circuit with a low-current signal, as in the
starter solenoid of an automobile,
Detect and isolate faults on transmission and distribution lines by
opening and closing circuit breakers (protection relays).
3.8. LOADS
Fig.9. Electrical Appliances Fig.10. 60V bulb
The various loads were connected at the feeder side. When the
consumption of power exceed the feeder is overloaded .Now a day’s various
electrical appliances like bulb, mixy , motor consuming huge amount of
power in residual areas .In industries huge power consumption devices like
motors, transformers require large power for working .For working of the
hardware one 40V bulb and one 60V bulb is used.
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According to the type of load using consumption of power
varies. For starting of the certain equipment require large power. During hot
days, the peak power consumption is significantly higher than normal loads.
Even though the power grid is designed to handle such peak loads, it is
possible that spurious excessive demand may cause power shutdown.
Together with ambient temperature, this could be leveraged to give enough
lead time to take the necessary measures to avoid excess load and potentially
massive power outages.
Use SAME FONT & FONT SIZE FOR ALL DOC
& Align all paragraph like this below
According to the type of load using consumption of power
varies. For starting of the certain equipment require large power. During hot
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days, the peak power consumption is significantly higher than normal loads.
Even though the power grid is designed to handle such peak loads, it is
possible that spurious excessive demand may cause power shutdown.
Together with ambient temperature, this could be leveraged to give enough
lead time to take the necessary measures to avoid excess load and potentially
massive power outages.
CHAPTER-4
CIRCUIT EXPLANATIONS
In circuit explanation we are explaining about the various
inter connections of each device. Each pin in each device has its own
functions.
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4.1. POWER SUPPLY
Fig11:Power supply circuit
The above figure shows the power supply circuit. Input is given
through DC adaptor. Diode IN4007 is to avoid the polarity inversion when
plugging. LED is for displaying the status. Capacitive filters are used to
eliminate ripples. 1000uF capacitor is electrolytic and 0.1uF is disc
capacitor. The capacitor filter should be rated at a minimum of 1000uF for
each amp of current drawn and at least twice the input voltage. The 0.1uF
capacitor eliminates any high frequency pulses that could otherwise interfere
with the operation of the regulator. Voltage regulators are very robust. They
can withstand over-current draw due to short circuits and also over-heating.
In both cases the regulator will shut down before damage occurs. The only
way to destroy a regulator is to apply reverse voltage to its input.
A IN4004, 1 amp power diode is connected in series with the
power supply. If the supply is connected the wrong way around, the
regulator will be protected from damage.
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R 21 . 2 K C 4
1 0 3
C 11 0 0 u F / 1 6 V
D 3
L E D
J 1
C O N 3
123
0
+5 V C CU 1L M 7 8 0 5 C / TO 2 2 0
1 3
2
I N O U T
GN
D
D 2
1 N 4 0 0 7 C 3
1000
uF/2
5V
C 2
1 0 4
+1 2 v
WIRELESS DISTRIBUTED LOAD SHEDDIND MANAGEMENT SYSTEM
The LM78XX series of three terminal regulators is available
with several fixed output voltages making them useful in a wide range of
applications. One of these is local on card regulation, eliminating the
distribution problems associated with single point regulation. The voltages
available allow these regulators to be used in logic systems, instrumentation,
HiFi, and other solid state electronic equipment. Although designed
primarily as fixed voltage regulators these devices can be used with external
components to obtain adjustable voltages and currents. The LM78XX series
is available in an aluminum TO-3 package which will allow over 1.0A load
current if adequate heat sinking is provided. Current limiting is included to
limit the peak output current to a safe value. Safe area protection for the
output transistor is provided to limit internal power dissipation.
If internal power dissipation becomes too high for the heat
sinking provided, the thermal shutdown circuit takes over preventing the IC
from overheating. Considerable effort was expanded to make the LM78XX
series of regulators easy to use and minimize the number of external
components. It is not necessary to bypass the output, although this does
improve transient response. Input bypassing is needed only if the regulator is
located far from the filter capacitor of the power supply
4.2. LCD DISPLAY
The LCD module is a parallel interface sixteen pin module. The
first three pins of LCD module are used for contrast adjusting. Here the first
pin is connected to ground, second to the voltage supply and third to the
variable resistor. The pins, seven to fourteen are data lines (D0 to D7). In
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this particular circuit the data lines D4 to D7 are used because the LCD
driver available is 4 line data bus. 15th pin is connected to the 5 volt supply.
Pin 4, 5, 6 are control pins, R/W, RS and enable respectively.
16th pin is connected to the ground through a transistor. The voltage from
pic16f877a turn on the transistor and it in turn turns on the LCD
backlight .Resistor R9 controls the voltage supplied to the transistor.
4.2.1. PINOUT
LCD modules may have a parallel or serial interface. The module
discussed here has a 14-pin parallel interface. The pin out for this module is
shown below.
4.2.1.1. Enable (E) :
This line allows access to the display through R/W and RS
lines. When this line is low, the LCD is disabled and ignores signals from
R/W and RS. When (E) line is high, the LCD checks the state of the two
control lines and responds accordingly.
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Table-2
4.2.1.2. Read/Write (R/W):
This line determines the direction of data between the LCD and
microcontroller. When it is low, data is written to the LCD. When it is high,
data is read from the LCD.
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SL.NO. SYMBOL FUNCTION
1 Vss Ground
2 Vcc +5V
3 VEE Contrast
4 RS H=Data, L=Instruction
5 R/W H=Read, L=Write
6 E Latch, HL
7 DB0 LSB
8 DB1
9 DB2
10 DB3
11 DB4
12 DB5
13 DB6
14 DB7 MSB
WIRELESS DISTRIBUTED LOAD SHEDDIND MANAGEMENT SYSTEM
4.2.1.3. Register select (RS) :
With the help of this line, the LCD interprets the type of data on
data lines. When it is low, an instruction is being written to the LCD. When
it is high, a character is being written to the LCD.
4.2.1.4. Contrast:
A variable voltage applied to this pin controls the contrast. Use
a potentiometer and adjust until you see the background.
4.2.1.5. DB0-DB7:
Apply the data or commands to these pins.
LCDs are more energy efficient and offer safer disposal than
CRTs. Its low electrical power consumption enables it to be used in battery-
powered electronic equipment. It is an electronically-modulated optical
device made up of any number of pixels filled with liquid crystals and
arrayed in front of a light source (backlight) or reflector to produce images
in colour or monochrome. The earliest discovery leading to the development
of LCD technology, the discovery of liquid crystals, dates from 1888.By
2008, worldwide sales of televisions with LCD screens had surpassed the
sale of CRT units
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4.3. MAX232
It consists of 16 pins.pin 1&3connected by a capacitor. Pin 4&5
connected through a capacitor. Pin 11 &12 connected to a 24&25 pin of PIC.
Pin 14&13 are connected to 2&3 pin of RS232. Pin 6 of MAX232and pin 5
of RS232 to GND through a capacitor C7.Pin 2 is connected to supply
through a capacitor
. +-----v-----+C1+-|1 16|- VccV+ -|2 15|- GNDC1--|3 14|- T1outC2+-|4 13|- R1inC2--|5 12|- R1outV- -|6 11|- T1inT2o-|7 10|- T2inR2i-|8 9|- R2out +-------+
Fig.13.Pin Layout of MAX 232(A) DIP Package
The MAX232(A) has two receivers (converts from RS-232 to TTL
voltage levels) and two drivers (converts from TTL logic to RS-232 voltage
levels). This means only two of the RS-232 signals can be converted in each
direction. The old MC1488/1498 combo provided four drivers and receivers.
There are not enough drivers/receivers in the MAX232 to also
connect the DTR, DSR, and DCD signals. Usually these signals can be
omitted when e.g. communicating with a PC's serial interface. If the DTE
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really requires these signals either a second MAX232 is needed, or some
other IC from the MAX232 family can be used (if it can be found in
consumer electronic shops at all). An alternative for DTR/DSR is also given
below. Maxim's data sheet explains the MAX232 family in great detail,
including the pin configuration and how to connect such an IC to external
circuitry. This information can be used as-is in own design to get a working
RS-232 interface. Maxim's data just misses one critical piece of information:
How exactly to connect the RS-232 signals to the IC one.
4.4. RS232 SERIAL PORT
It consists of 6 pins, out of this pin 3&2 are connected to 13&14
of MAX232. Pin 5 is connected to gnd.
MAX232 to RS232 DB9 Connection as a DCE
MAX232 Pin No. MAX232 Pin Name Signal Voltage DB9 Pin
7 T2out RTS RS-232 8
8 R2in CTS RS-232 7
9 R2out CTS TTL n/a
10 T2in RTS TTL n/a
11 T1in TX TTL n/a
12 R1out RX TTL n/a
13 R1in TX RS-232 3
14 T1out RX RS-232 2
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15 GND GND 0 5
Table-3
4.5. FEEDERS
3 relays were used, out of this two for 2 feeders and one for
transformer. Relay has 3 pins N0, NC,C. if the switch is closed position then
connected to NC. Three resistors were connected across 3 relays. 3 resistor
pin connections were connected to 16,17,18 pin of PIC. A 12v supply is
taken from power supply circuit.
4.6.CIRCUIT FABRICATION AND SOLDERING DETAIL
4.6.1.Pcb fabrication
Printed Circuit Broad (PCB) is a mechanical assembly
consisting of layers of fiberglass sheet laminated with etched copper
patterns. It is used to mount electronic parts in a rigid manner suitable for
packaging.
The type of integrated circuit components used in the
fabrication process has an important role in the design of PCB. The
conductor width, spacing between the signal conductors etc, are calculated
to give optimum wave impedance of the conductor's lines. Optimum wave
impedance gives minimum delay or rising and trailing edge of the pulse in
digital circuit.
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4.6.2.Soldering
Soldering is an important skill for electrical technician. Good
soldering is important for proper operation of equipment.Solder is an alloy
of tin and lead. The solder that is most used is60/40 solder. This means that
it is made from 60% tin and 40% lead. Solder melts at a temperature of
about 400 degree Fahrenheit. For solder to adhere to join, the parts must to
enough to melt the solder. Rosin flux is contained inside the solder. It is
called rosin-core solder. A good mechanical joint must be made when
soldering. Heat is then applied until the material rare hot. When they are hot,
solder is applied to the joint. The heat of the metal parts is used to melt the
solder. Only a small amount of heat should be used sparingly. The joint
should appear smooth and thin. If it does not, it could be a "cold" solder
joint. This is called a “cold joint". Care should be taken not to damage PCB
when soldering parts on to them. Small, low wattage irons should be used
with PCB and semiconductor devices
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Fig.14.Board connection
Change with a new figure
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Fig.15.Circuit diagram of hardware
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CHAPTER-5SOFTWARE DEVELOPMENT TOOLS
Write about the software and how did you burn the
program to MC
Program codes are generally shown in appendix 1 or 2
Clarify this the project coordinator 5.1. PROGRAM FOR MICROCONTROLLER:
#include<16f877a.h>
#include"pic1.h"
#include"lcd1.h"
#define transformer rc1
#define fr1 rc2
#define fr2 rc3
int count,p,pflg=0,t;
int fr1flg=1,fr2flg=1,trflg=1,f1,f2,afl;
char kseb[]="9486669772";
void sms_send(void)
{
putchar(26);
delay_ms(200);
}
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void sms_start_kseb(char*ch)
{
printf("AT+CMGF=1\r");
printf("AT+CMGS=");
printf("\"+91");
printf("%s\"\r",ch);
}
#int_RTCC
RTCC_isr()
{
count++;
if (count>100000)
{
count=0;
fr1
flg=1,fr2flg=1,trflg=1;
fr1=fr2=transformer=afl=1;
set_timer0(0x00);
}
}
float feeder1()
{
set_adc_channel(0);
delay_us(20);
if(fr1flg&&trflg) // Checking status of F1
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return(read_adc());
}
float feeder2()
{
set_adc_channel(1);
delay_us(20);
if(fr2flg&&trflg) // Checking status of F2
return(read_adc());
}
float temp()
{
set_adc_channel(2);
delay_us(20);
if(trflg)
return(read_adc()*5.0/255*100);
}
void grace_period()
{
pflg=0;
while(p<18)
{
p=p+1;
delay_ms(2000); //20000
go(64);
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print(p);
delay_ms(300);
}
pflg=1;
clrscr();
}
void sms_start_c(char*ch)
{
printf("AT+CMGF=1\r");
printf("AT+CMGS=");
printf("\"+91");
printf("%s\"\r",ch);
printf("Please reduce your power consumption\r");
printf(" or else you might suffer Power Loss!\r");
printf("Thank You....");
sms_send();
}
void main()
{
int k,i,f1,f2,f1flg;
char msg[ ]="WDL SMS";
char F1C1[ ]="9791668561";
char F1C2[ ]="9655166177";
char F1C3[ ]="9787239229";
char F2C1[ ]="7708311801";
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WIRELESS DISTRIBUTED LOAD SHEDDIND MANAGEMENT SYSTEM
char F2C2[ ]="9487449774";
char F2C3[ ]="9496369807";
char trsf[ ]="Transformer is Off";
trisd=0x00;
trisc1=trisc2=trisc3=0;
enable_interrupts(global);
enable_interrupts(INT_RTCC);
setup_adc_ports(ALL_ANALOG);
setup_adc(ADC_CLOCK_INTERNAL);
setup_timer_0 (RTCC_INTERNAL|RTCC_DIV_256);
set_timer0(0x00);
TRISB=0X00;
fr1=fr2=transformer=1;
lcdinit();
go(4);
prints(msg);
delay_ms(800);
clrscr();
afl=0;
f1flg=1;
while(1)
{
f1=feeder1();
f2=feeder2();
if(f2>200)
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f1flg=0;
else
f1flg=1;
pflg=0;
go(0);
printc("F1=");
go(3);
//clrscr();
if(!f1flg)
f1=0;
print(f1);
delay_ms(700);
go(8);
printc("F2=");
go(11);
//clrscr();
print(f2);
delay_ms(700);
t=temp();
go(67);
printc("Temp=");
go(73);
print(t);
delay_ms(200)
if(t>45)
{
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sms_start_kseb(kseb);
printf("High Temp : TRANSOFRMER IS OFF\r");
sms_send();
transformer=fr1=fr2=0;
trflg=0;
go(64);
prints(trsf);
delay_ms(500);
clrscr();
}
if(f1>140)
delay_ms(200);
if(f1>140)
{
if(!pflg)
{
clrscr();
go(68);
printc("F1 HIGH");
delay_ms(200);
sms_start_c(F1C1);
sms_send();
sms_start_c(F1C2);
sms_send();
sms_start_c(F1C3);
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sms_send();
}
p=0;
grace_period();
}
if(f2>230)
{
delay_ms(200);
if(f2>230)
{
if(!pflg)
{
clrscr();
go(68);
printc("F2 HIGH");
delay_ms(200);
sms_start_c(F2C1);
sms_send();
sms_start_c(F2C2);
sms_send();
sms_start_c(F2C3);
sms_send();
}
p=0;
grace_period();
}
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}
if(pflg)
{
f1=feeder1();
if(f1>140)
{
fr1=0;
fr1flg=0; // If Feeder1 off
pflg=0;
sms_start_kseb(kseb);
printf("Feeder1 Is OFF");
sms_send();
clrscr();
printc("Feeder1 Is OFF");
delay_ms(500);
clrscr();
}
}
if(pflg)
{
f2=feeder2();
if(f2>230)
{
fr2=0;
fr2flg=0; //If Feeder2 off
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pflg=0;
sms_start_kseb(kseb);
printf("Feeder2 Is OFF");
sms_send();
clrscr();
printc("Feeder2 Is OFF");
delay_ms(500);
clrscr();
}
}
}
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WIRELESS DISTRIBUTED LOAD SHEDDIND MANAGEMENT SYSTEM
CHAPTER-6
CONCLUSION
Wireless Distributed Load Shedding Management System
(WDL-SMS) was implemented and tested. It was verified to operate
successfully under standard and caution modes. GSM network was
successfully used in remote monitoring and control .Recent advances in the
technology can be leveraged in order to make WDL-SMS more stable and
feature-rich.
NOT NEEDED
Here we are glad to present the project titled as “WIRELESS
DISTRIBUTED LOAD SHEDDING MANAGEMENT SYSTEM’’. We
have introduced our project in small scale manner to expose large ideas in
transformer side.
We are sure that this project is very useful and needful one to all.
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WIRELESS DISTRIBUTED LOAD SHEDDIND MANAGEMENT SYSTEM
CHAPTER-7
FUTURE SCOPE
In the future the system could call the mobile technicians
and use a pre-recorded voice to tell the fault rather than sending SMS .It can
also E-mail a summary of readings of all transformers to employees on a
regular basis. It can monitor, record and update transformer parameters more
frequently. In future an Artifical Neural Network(ANN)can be used in
forecasting, or predicting overloads and abnormal conditions.ANN can be
configured to recognize specific pattern or data classification, through a
learning process.
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DON’T PUT CHAPER NO FOR APPENDIX , Just write it as APPENDIX I or APPENDIX II
CHAPTER-8
APPENDICES
8.1.USART
The Universal Synchronous Asynchronous Receiver Transmitter
module is one of the two serial I/O modules
The USART can be configured
as a full duplex asynchronous system
or it can be configured as a half duplex synchronous
8.1.1.USART MODULE The USART can be configured in these modes:
Asynchronous (full duplex)
Synchronous - Master (half duplex)
Synchronous - Slave (half duplex)
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Bit SPEN (RCSTA<7>) and bits TRISC<7:6> have to be set to
configure pins RC6/TX/CK and RC7/RX/DT as the USART
The USART module also has a multi-processor communication
capability using 9-bit address detection.
8.1.2.FULL DUPLEX ASYNCHRONOUS OPERATION
The most common use of the USART in asynchronous mode is to
communicate to a PC serial port using the RS-232 protocol.
The UART can both transmit and receive
Full duplex operation - Both transmission and reception
can occur at the same time
The USART Asynchronous module consists of
Sampling Circuit
Asynchronous Transmitter
Asynchronous Receiver
8.1.3.BAUD RATE FORMULA
Formulas for baud rate
Baud rate = Fosc/(16(SPBRG+1)), BRGH=1
Baud rate = Fosc/(64(SPBRG+1)), BRGH=0
Formulas for SPBRG
SPBRG = (Fosc/(16 x Baud rate)) - 1, BRGH=1
SPBRG = (Fosc/(64 x Baud rate)) - 1, BRGH=0
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8.2.MC78XX/LM78XX/MC78XXA
3 –Terminal 1A positive voltage regulator
8.2.1.FEATURES:
Output current up to 1A
Output voltage of 5,6,8,9,10,12,15,18,24V
Thermal overload protection
Short circuit protection
Output transistor safe operating area protection
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Table-5
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8.3. CAD SOFT EAGLE
EAGLE (Easily Applicable Graphical Layout Editor) is a
proprietary ECAD program produced by Cad Soft in Germany (American
marketing division: Cad Soft USA). It is very commonly used by private
electronics enthusiasts, because there is a free limited version for non-profit
use and it is available in English and German. Cad Soft has released versions
for Microsoft Windows, Linux, and Mac OS X.
EAGLE contains a schematic editor, for designing circuit
diagrams and a PCB layout editor, which allows back annotation to the
schematic.
EAGLE includes a basic but functional autorouter, or
alternatively manual routing can be performed. PCBs designed in EAGLE
are accepted by a large amount of PCB fabrication houses without the need
to export. EAGLE is very popular with hobbyists because both a basic free
edition (with a lower feature set) and a low cost non-profit edition are
available.
Schematic capture or schematic entry is a step in the design
cycle of electronic design automation (EDA) at which the electronic
diagram, or electronic schematic of the designed electronic circuit is created
by a designer. This is done interactively with the help of a schematic capture
tool also known as schematic editor.
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Fig.19
The circuit design is the very first step of actual design of an
electronic circuit. Typically sketches are drawn on paper, and then entered
into a computer using a schematic editor. Therefore schematic entry is said
to be a front-end operation Therefore schematic entry is said to be a front-
end operation of several others in the design flow.
Despite the complexity of modern components – huge ball grid
arrays and tiny passive components – schematic capture is easier today than
it has been for many years. CAD software is easier to use and is available in
full-featured expensive packages, very capable mid-range packages that
sometimes have free versions and completely free versions that are either
open source or directly linked to a printed circuit board fabrication company.
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In past years, schematic diagrams with largely discrete
components were fairly readable however with the newer high pin-count
parts and with the almost universal use of standard letter-sized paper,
schematics have become less so. Many times, there will be a single large
part on a page with nothing but pin reference keys to connect it to other
pages.
Readability levels can be enhanced by using buses and super
buses, related pins can be connected into a common bus and routed to other
pages. Buses don't need to be just the traditional address or data bus directly
linked pins. A bus grouping can also be used for related uses, such as all
analog input or all communications related pin functions.
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REFERENCES
1. A.Saffarian,M.Sanaye pasand,H.Asadi,”Performance Investigation of
New combinational load shedding schemes”,joint Internatonal Conference
on Power System Technology and IEEE power India Conference,2008
2. “Architecture of PIC Micro controller ”, www.microchip.com
3. Dellon.T.Horn ‘How to test almost anything electronics’
4. F. Capitanescu , B. Otomega,H. Lefebvre ,V. Sermanson,T.Van Cutsem,
Decentralized tap changer blocking and load shedding against voltage
instability”: Prospective tests on the RTE system ,Electrical Power and
Energy Systems.
5. IEEE,”Guide for loading mineral-oil –immersed transformers,”,IEEE
std.C57.91-1995.
6. http://robosoftsystems.co.in/roboshop/index.php/electronics-components/
led-display/16x2-alphanumeric-lcd-hd44780 “ LCD Display”
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WIRELESS DISTRIBUTED LOAD SHEDDIND MANAGEMENT SYSTEM
7. http://en.wikipedia.org/wiki/555_timer_IC , “Working details of 555
Timer IC”
8. J. J.Ford ,H. Bevrani ,G. Ledwich ,”Adaptive Load shedding and
regional protection” ,International Journal of electrical power and energy
systems.
9. Ubald ‘Fundamentals Of Electronics’
10.“Voltage regulator LM 7805”, http://www.national.com/search/
LM7805.html
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