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Automatic Street Light Control
Based on traffic Density
Abstract
Monitoring of street lights and controlling is of utmost importance in developing country like
India to reduce the power consumption. This project presents a street light control system
which combines various technologies: a timer, Liquid Crystal Display (LCD), a statistics of traffic
flow magnitude, a photosensitive detector (LDR), infrared photoelectric control, Light Emitting
Diodes (LED), power transistors, dual relays and wireless communication (ZigBee). This system
contains light sensor to observe the day and night detection to turn lamps on, merely during
night time. It also includes infrared detectors to turn light on automatically when vehicles,
pedestrians pass by, later turn off after a certain predefined delay for even more energy
conserving. This system also includes fault detection and feedback circuit to indicate the present
state of the control system.
Understanding Pulse Width Modulation (PWM)
Pulse Width Modulation (PWM) is a commonly used technique for generally controlling
DC power to an electrical device, made practical by modern electronic power switches. However
it also finds its place in AC choppers. The average value of current supplied to the load is
controlled by the switch position and duration of its state. If the On period of the switch is longer
compared to its off period, the load receives comparatively higher power. Thus the PWM
switching frequency has to be faster.
Typically switching has to be done several times a minute in an electric stove, 120 Hz in a
lamp dimmer, from few kilohertz (kHz) to tens of kHz for a motor drive.
Switching frequency for audio amplifiers and computer power supplies is about ten to
hundreds of kHz. The ratio of the On time to the time period of the pulse is known as duty cycle.
If the duty cycle is low, it implies low power.
The power loss in the switching device is very low, due to almost negligible amount of
current flowing in the Off state of the device and negligible amount of voltage drop in its off state.
Digital controls also use PWM technique.
PWM has also been used in certain communication systems where its duty cycle has been
used to convey information over a communications channel.
Power delivery
PWM can be used to adjust the total amount of power delivered to a load without losses normally
incurred when a power transfer is limited by resistive means. The drawbacks are the pulsations
defined by the duty cycle, switching frequency and properties of the load. With a sufficiently high
switching frequency and, when necessary, using additional passive electronic filters the pulse
train can be smoothed and average analogue waveform recovered. High frequency PWM control
systems can be easily implemented using semiconductor switches.
As has been already stated above almost no power is dissipated by the switch in either on or off
state. However, during the transitions between on and off states both voltage and current are nonzero and thus considerable power is dissipated in the switches. Luckily, the change of state
between fully on and fully off is quite rapid (typically less than 100 nanoseconds) relative to
typical on or off times, and so the average power dissipation is quite low compared to the power
being delivered even when high switching frequencies are used.
Modern semiconductor switches such as MOSFETs or Insulated-gate bipolar transistors (IGBTs)
are quite ideal components. Thus high efficiency controllers can be built. Typically frequency
converters used to control AC motors have efficiency that is better than 98 %. Switching power
supplies have lower efficiency due to low output voltage levels (often even less than 2 V for
microprocessors are needed) but still more than 70-80 % efficiency can be achieved.
This kind of control for AC is power known delayed firing angle method. It is cheaper and
generates lot of electrical noise and harmonics as compared to the real PWM control that develops
negligible noise.
Introduction to Project
Automation,
Power consumption
and
Cost Effectiveness
are
the
important
considerations in the present field of electronics and electrical related technologies. Industry of
street lighting systems are growing rapidly and going to complex with rapid growth of
industry and cities. To control and maintain complex street lighting system more economically,
various street light control systems are developed. These systems are developed to control and
reduce energy consumption of a town's public lighting system using different technologies.
These range from controlling a circuit of street lights and/or individual lights with specific
ballasts and network operating protocols.
They may include sending and receiving instructions via separate data networks, at
high frequency over the top of the low voltage supply or wireless. Various protocols have been
developed as well as compatible hardware for most types of lighting. A multi-functional street
light control system, which is more electricity conserving and convenient, is presented here
in this paper.
Main goal of the proposed work is to control switching of street light automatically
according to light intensity, to develop traffic flow based dynamic control statistics using
infrared detection technology and maintain wireless communication among lampposts.
This proposed system utilizes the latest technology for the sources of light as LED Lamps
instead of generally used street lamps such as High Pressure Sodium Lamps, etc. The LED
technology is preferred as it offers several advantages over other traditional technologies like
energy saving due to high current luminous efficiency, low maintenance cost, high color
rendering index, rapid startup speed, long working life etc. This proposed system makes use of
infrared photoelectric sensor
for vehicle detection
Some of the advantages of infrared detectors are that they can be operated during both day and
night, and they can be mounted in both side and overhead configurations. In this developed
prototype, they are mounted in side configurations.
RELATED WORKS
Energy savings are of utmost importance today. The goal is therefore, the reduction of
operating
prices of
street lighting
with
the
creation
of
a
system
characterized
by
straightforward installation and low power consumption. A multi-functional street lights control
system based on AT89S52 was presented. This system included a time cut-out function and an
automatic control pattern for electricity conservation. This design can save a great amount of
electricity compared to street lamps that keep alight during nights. Furthermore, this system has
auto-alarm function which will set off if any light is damaged and will show the serial
number of the damaged light, thus it is easy to be found and repaired the damaged light .
BLOCK DIAGRAM OF PROPOSED SYSTEM
The block diagram of proposed street lights control system is shown in Figure 2 (a) and Figure
2 (b). The transmitter end consists of power supply, microcontroller AT89S52, photosensitive
detection circuit (Day & night sensor),infrared vehicle detector, feedback circuit, fault
detection circuit, LCD display and ZigBee transmitter module. The receiver part consists of
ZigBee receiver module,MAX232, RS232 and PC. The block diagram explains the simple working
of the whole system developed.
The power supply circuit provides the 5V regulated power supply
for revitalizing
the
microcontroller module. The core of the system is an AT89S52 microcontroller. It is
preferred because of the following features:- it is a low-power, high-performance CMOS 8bit microcontroller with 8K Bytes of in-system programmable Flash memory, 256 bytes of RAM,
32 I/O lines, three 16-bit timer/counters, a full duplex serial port, on-chip oscillator, and supports
two software selectable power saving modes: low power Idle and Power- down mode. The
photosensitive detection circuit consists of Day & night sensor to determine the external
light intensity. The threshold (reference) illumination level is set initially. The photoelectric
sensor with set threshold intensity is used to observe street conditions as the intensity of
daylight and, depending on the conditions they activate or off the lamps. The street lamps still
consume a lot of electricity when merely a few vehicles are driving around the road. Thus,
there is a great necessity to develop a control system based on the traffic flow density. Whenever
there is no traffic i.e. density of traffic is zero, there is no need of street light to be glow on
highways which saves power consumption to a greater extent. The lights of a particular area
should glow only when a vehicle enters that area on highways. For this purpose, the infrared
detection circuit has been used. It consists of IR sensor (presence sensor) which has the task of
identifying the passage of a vehicle or pedestrian causing the switching ON/OFF of street
lamps.
This feature permits to activate lamps solely when necessary, avoiding wastage of
energy. The load which is street-light lamps is connected to microcontroller. Using power
transistors and solid state dual relays, the street-lamps are switched ON/OFF. The solid state
relays accept the triggering voltage from power transistors which in turn are triggered
by
microcontroller on reception of activation signals from the sensors. The fault detection
circuit indicates the LED lamp failure as well as wire fault along with lamp and wire number
when the lamps are firstly turned on, on sensing the night. Through feedback circuit the
malfunctioning message is transmitted to the controller which displays it. The LCD display is
used to show different conditional messages like day, night, light testing, wire fault, LED
failure, etc [LCD is Optional].
The block diagram of proposed street lights control system is shown in Figure 2 (a) and Figure 2
(b). The transmitter end consists of power supply, microcontroller AT89S52, photosensitive
detection circuit (Day & night sensor),infrared vehicle detector, feedback circuit, fault
detection circuit, LCD display. The block diagram explains the simple working of the whole
system developed. All the operation is regulated by a timing management that permits the system
is set for predestined time.
When the signal is detected at the point S, the state of lamp A switched (On to Off or Off to
On), when the signal gets detected at the point B, the states of lamp A and lamp C are
switched on or off simultaneously, while point D detects the signal, lamp C and lamp E are
switched on or off simultaneously, while S’ detects the signal, lamp E is switched on or off.
Advantages
In the current system, maximum lightning over the freeways is completed through HID
(High Intensity Discharge lamps), the energy utilization of HID lamps/lanterns are high. The
intensity of HID lamps cannot be controlled, in harmony to the necessity, therefore there is a
requirement to swap to a substitute way of illumination system i.e., by making use of LEDs. This
lighting system is constructed to conquer the disadvantages of High Intensity Discharge lamps.
This lightning system exhibits the utilization of the Light emitting diodes or LED’s as the
source of light and its intensity control is variable which can be altered as per the requirement.
LED’s use a lesser amount of power and its life span is good, in comparison to the old HID
lanterns/lamps. The more vital and motivating characteristic is that the intensity of LED’s can be
controlled as per the requirement throughout non-peak hours which is not possible with HID
lanterns/lamps.
A bunch of LEDs are brought into play to structure a street light. The micro-controller
includes planned instructions which are used for controlling the intensity of lanterns based on
Pulse width modulation (PWM) produced indicators. The lights intensity are kept soaring all
through the peak hours, because the street traffic have a propensity to reduce slowly during late
night hours, the intensity of the traffic also declines gradually till sunrise. Finally it’s totally shuts
down at dawn, and it’s all over again restarts at 6pm during the dusk. The course of action is
repeated.
Circuit Diagram
IR Sensor Circuit
Infrared beam barrier and a proximity detector circuit with IC 555
Fig.Iinfrared detector circuit
The circuit uses the very popular Sharp IR module. NOS pin. circuit is shown in the Sharp
and Panasonic modules. For other modules please refer to the relevant datasheets.
The receiver consists of a 555 timer IC working as an oscillator at about 38Khz (also works from
36kHz to 40kHz), which must be configured using the standard 10K. The duty cycle of the IR
beam is about 10%. This allows us to more current through the LED, allowing a greater range.
The receiver uses a sharp IR unit. If the IR beam from the transmitter IR drops, the output is
activated, which activates the relay and turns off when the beam is blocked. The relay contacts can
be used to turn ON / OFF alarm, lights etc. The 10K advance should be adjusted until the receiver
detects the IR beam.
The circuit can also be used as a proximity sensor that objects in front of the device detects
without obstructing a IR beam. So the LED has the same direction as the IR module and at the
same level. The proposed scheme is shown in diagram. The LED should be adequately covered
with a reflective material like glass or aluminum plates on the sides to stop the spread of the IR
beam
to
prevent
and
get
a
sharp
focus
the
beam.
When there is nothing for them, the IR beam reflected on the unit and therefore the circuit is not
activated. When an object comes near the device, the infrared light from the LED reflected from
the
object
on
the
unit
and
therefore
the
circuit
is
activated.
If there is still a very bad start, use a 1uF or higher CAPACITOR instead of the 0.47uF.
ADVANTAGES AND DISADVANTAGES
Advantages:

Photo resistors convert light into electricity and are not dependent on any other force.

LDRs are sensitive, inexpensive, and readily available devices. They have good power and
voltage handling capabilities, similar to those of a conventional resistor.

They are small enough to fit into virtually any electronic device and are used all around the
world as a basic component in many electrical systems.

Photo resistors are simply designed and are made from materials that are widely available,
allowing hundreds of thousands of units to be produced each year.

A LDR may be connected either way round and no special precautions are required when
soldering.
Disadvantages:

Can be more complicated to align detector pairs.

Is sensitive to ambient light and require careful shielding.

Photo resistors are only sensitive to light and no other force can power it without risking
damage. Also, they are unable to detect low light levels and may take a few seconds to
deliver a charge while their electrons build up momentum.
APPLICATIONS

Photo resistors have many uses, most of which involve detecting the presence of light.
Street lights use photo resistors to detect whether it is day or night and turn the light on or
off accordingly.

Photo resistors are also used in digital cameras to detect how much light
camera sees and adjust the picture quality accordingly.

They are also used in some clocks, alarms, and other electronic devices that are semidependent on sunlight.

Smoke detection.

Automatic lighting control.

Burglar alarm systems.

Camera (electronic shutter).

Strobe (color temperature reading).
APPLICATIONS
1) Military and aerospace embedded software applications
2) Communication Applications
3) Industrial automation and process control software
4) Mastering the complexity of applications.
5) Reduction of product design time.
6) Real time processing of ever increasing amounts of data.
7) Intelligent, autonomous sensors.
3. BLOCK DIAGRAM
Fig.3.1: block diagram of the project
CONCLUSION
This project of DENSITY SENSED STREET LIGHT INTENSITY CONTROL TO SAVE
ENERGY is a cost effective, practical, ecofriendly and the safest way to save energy. It clearly tackles the
two problems that world is facing today, saving of energy and also disposal of incandescent lamps, very
efficiently. According to statistical data we can save more that 40 % of electrical energy that is now
consumed by the highways. Initial cost and maintenance can be the draw backs of this project. With the
advances in technology and good resource planning the cost of the project can be cut down and also with the
use of good equipment the maintenance can also be reduced in terms of periodic checks. The LEDs have
long life, emit cool light, donor have any toxic material and can be used for fast switching. For these reasons
our project presents far more advantages which can over shadow the present limitations. Keeping in view
the long term benefits and the initial cost would never be a problem as the investment return time is very
less.
The project has scope in various other applications like for providing lighting in industries,
campuses and parking lots of huge shopping malls. This can also be used for surveillance in corporate
campuses and industries.