paper 1- a highly efficient street lighting system using power led
TRANSCRIPT
A Highly Efficient Street Lighting System Using Power LED
Mr. Sarang Premalwar, Mr. Rohan Moon, Mr. Sagar Adhau
Abstract - This work presents a highly efficient street lighting system based on both solar energy as well as batteries and light emitting diodes (LEDs) as lighting source. This system is being presented as an alternative for remote localities, like roads and crossroads. Besides, it presents high efficiency, because all power stages are implemented in DC current. The design of LEDs fixture, in order to replace a 200 W high pressure sodium (HPS) lamp, is performed. This design takes into account the human eye response in scotopic conditions. LEDs driver and battery charger experimental results are presented. The battery charger presents three control modes: maximum power point tracker (MPPT) mode; constant current mode; and constant voltage mode. The control mode depends on the battery state (charged/discharged), and solar irradiance level.
Keywords— Street lighting, LEDs, Solar Energy,
Batteries. Power supply unit.
I. INTRODUCTION
LED technology has rapidly developed in recent years to the point that LEDs can be seriously considered for replacing conventional halogen and incandescent lamps in general illumination, e.g. street lighting. Before widespread adaption of this technology can be embraced. There are number of outstanding issues that need to be addressed. The opportunity is now available for the implementation of this innovative concept. Nowadays, the power plant in our country are predominantly based on thermoelectric energy. This happens because of high thermoelectric potential of our country. However, due to our country continental dimensions, the energy distribution system is very huge and expensive and besides this huge energy distribution system, there
are a lot of localitie without energy supply. The objective of this work is to develop an autonomous street lighting system for remote places, with high efficiency and long lifetime, using alternative energy. Besides, this solution can also be adopted as an alternative for the conventional street lighting systems in urban centers. Nowadays, the most important renewable energy systems are based on wind energy and solar energy. wind-turbine technology has undergone a dramatic transformation during the last 15 years, developing from a fringe science in the 1970s to the wind turbine of the 2000s using the last in power electronics, aerodynamics, and mechanical designs. Solar-electric-energy has grown consistently by 20%-25% per year over the past 20 years, which is mainly due to the decreasing costs and prices. This decline has been driven by
1) efficiency increase of solar cells;2) manufacturing technology improvements; and3) economies of scale.
In the case of an autonomous street lighting system, the best solution is the solar energy option, because of the long lifetime, easy installation, and modularity. The main lamp types used in street lighting are the high pressure discharge lamps, e.g.: mercury vapour lamps, HPS lamps, and metal halide lamps. The discharge lamps demand a ballast that provides their starting and steady state behavior, which is commonly electromagnetic. Lighting emitting diodes (leds) are being presented as an alternative to replace the conventional lighting systems. Besides their use as signalizing systems is much broadcasted, they are not commonly used as lighting systems. however, recent technology is improving gradually the leds efficiency and color quality, which allows their application in lighting systems. The main advantages of using leds in the proposed lighting system are: their long lifetime (100,000 hours) that is compatible with the solar panels lifetime (higher than 25 years); and their dc supply.
II. STREET LIGHTING REQUIREMENTS
Streets lights are subject to demanding conditions; environmentally, electrically and optically. It is generally taken for granted that street light luminaries have to operate in all weather conditions, during large temperature variations,
varying humidity, high wind speeds and must be
immune to dust and insect ingress. Electrically, the luminaries must provide ; good power factor , high operating efficieny, system protection, meet EMC IEMI standards and must regulate the current supply to the light engine in order to control light output. Optically, the luminaries must sufficiently illuminate a specified area, while maintaining good colour temperature, but minimizing glare and generating no stroboscopic effects.
III. – POWER LED
Fig 1: Power LED
Light emitting diode (led) differs from conventional light sources; it provides a direct transfer of electrical energy into light. Although there are many lighting technologies, led has been foreseen as an ‘ultimate lamp’ for the future [theoretically, led has many distinctive advantages such as high efficiency, good reliability, long life, variable colour and low power consumption. recently, led has begun to play an important role in many fields, so that led products are now being used in many fields including traffic lights, vehicleheadlights and backlights, lcd displays and street lamps and so on led is expected to be used in general lighting, which consumes about 15% of the total energy around the world. it is believed that high-power led will be the dominant lighting technology by 2025.
The led market has grown significantly since the development of high-intensity blue and white leds. Today, leds play animportant role in many applications including displays, signs, back-lights, automotive and aircraft lighting, and trafficsignals and specially “street lights”. LEDs will also soon play a much larger role in the future of architectural lighting and general illumination. There’s no doubt about it: leds have a brilliant future. Brighter and more energy efficient than a conventional filament lamp, leds can have a service life of more than 100,000 hours. However, most leds have a relatively large emitting area.
IV. PROPOSED STREET LIGHTING SYSTEM
Fig. 2: Block diagram of Power LED Street Lighting System
The LED lamps have been designed so they can be mounted in to existing The LED lamps consist of four 1ft PCB sections with appropriate interconnections to allow up to five series stringsof LEDs. fluorescent fittings. By using existing fittings and wiring in commercial buildings, the cost of retro-fitting the LED lamps can be reduced. Existing fluorescent fittings include ballast circuitry to start and operate the fluorescent tubes; this must be removed and replaced with a new driver circuit. A single heat sink runs along the back of the interconnected PCBs for cooling.
V. POWER SUPPLY UNIT
Unlike a conventional power or signal diode, ultra-bright high power LEDs cannot be subjected to reverse voltage. If exposed to such a condition, then failure is certain. Also for long-life,
high – peak current should be avoided. Hence the
simple option of connecting anti-parallel LED strings to the mains through current limiting impedances is not advisable if long life is demanded. An array of LEDs must be supplied from the mains via a converter which protects them from reverse voltage and surge whilst regulating
output current. For all electronic equipment connected to the mains, operating at levels of 50W upwards there is a concern about harmonic pollution introduced into the mains supply. Recent legislation and updated international standards stringently enforce the harmonic current limits that can be drawn by the off-line equipment, so as to reduce supply voltage distortion.
With regard to the fundamental current, since street lighting authorities pay a tariff for low power factor, it is advisable also to provide power factor correction. There are a number of techniques that can be used to achieve both high power factor and low harmonic pollution; the two main approaches broadly fall into two categories, passive and active.
Figure 3: Block diagram of PSU and LED arrays.
A detailed literature review revealed that in order to achieve high power factor and low harmonic distortion, whilst maintaining good reliability and low cost, an active Power Factor Correction, PFC, converter operating in the discontinuous current mode could be implemented . Further, electrolytic capacitors should be avoided within the luminaire, as they will dry out at the high temperatures to be found there. However, eliminating electrolytic capacitors will have a severe impact upon the operation of the PFC converter, since in order to avoid 100Hz stroboscopic effects, an energy store is required from which the LEDs will be supplied twice per cycle as mains voltage goes through zero.Thus a non-electrolytic capacitor is required which can operate at the elevated temperatures within the luminaire and, being inevitably lower in value than an electrolytic capacitor, this capacitor must store energy at a high voltage. This requirement instantly narrows the PFC converter options to those that can boost the output voltage.
A block diagram of the proposed luminaire PSU is shown in Figure 3. It comprises a buck-boost PFC input stage. It output is fed to LED arrays via individual current regulator circuits, which are buck dc/dc converters. These buck converters regulate the current through the LED arrays, enabling independent operation modes. Finally, protection of the LEDs needs to be considered against over temperature, over voltage and over currents.
VI. COMPARISON OF LED LIGHT WITH HIGH POWER SODIUM LAMP:
Parameters HPS STEERTLIGHT
LED Streetlight
Remark
Lamp power consumption
150W 56W
Electrical distribution
Rectifier45W
Switching Power10W
Total Lamp’s Power consumption
245W 72 W
Daily consumption
2.94 kWh 0.86 kWh Calculated by 12 hours a day
Consumption per month
89.38 kWh 26.14 kWh Calculated on a 30.4 days basis
Consumption per year
1073.84 kWh 314.11 kWh
Calculated on a 365.25 days basis
10 year’s consumption
10738.35 Kwh
3141.1 Kwh
estimation
VII. BATTERY BANK
Considering that the proposed system will be installed in isolated or remote locations, the electricity storage system (battery bank) must present high energy efficiency, reliabilityand low maintenance needs.The capacity and useful life of a battery depends on a variety of factors, such as charge and discharge routines, maintenance, temperature and age. Within these factors, the charge and discharge routines present the greatest influence on the useful life and the battery’s capacity .The choice of the most suitable charge method depends mainly on thetype of battery and its application. In the case of VRLA (Valve Regulated Lead Acid) batteries, one of the most suitable and easiest implementation methods is the IU method (one current level and one voltage level) Batteries used in photovoltaic systems are exposed to a large amount of operating conditions, due to the non-linearity of the primary source (sun). Taking into account the costs of each component, the battery bank becomes the most onerous in a photovoltaic system, representing as much as 15% of the initial costs for installation of the photovoltaic system, or even up to 46% if maintenance costs are taken into account.
VIII. SOLAR PANEL
Primary source of charging of this project is solar charging. Solar panel consists of number of photovoltaic cells. Photovoltaic solar energy is the energy obtained by directly converting light into electricity. The base device responsible for performing this conversion is the photovoltaic cell Photovoltaic cells are made of a semiconducting material - usually silicon (Si) - into which substances, known as dopants, are added in such a way as to create an appropriate medium for establishing the photovoltaic effect. These cells are made of monocrystals, polycrystalline crystals or amorphous silicon. Monocrystalline photovoltaic cells are manufactured through a process that begins with a high purity silicon more efficient cells (15-18%). However, the raw material needed to achieve this purity is extremely costly. Polycrystalline photovoltaic cells are produced through the process of mixing several sheets of silicon crystal. As this process requires a less
rigorous preparation process for the cells, these are less expensive than those made with monocrystals, although efficiency is reduced (13-15%).Owing to their characteristics, monocrystalline photovoltaic panels were chosen, since they are more efficient, and their increased cost does not significantly affect the final cost of the commercial panels.
IX. CONCLUSION
This work has proposed an autonomous street lighting system, which uses solar energy as primary source, batteries as secondary source, and LEDs as lighting source. This system is an interesting solution for remote localities, as for roads and crossroads.The system presents high efficiency, since all the power stages are DC-DC. This kind of conversion yields an easy implementation and control.The LEDs technology has been significantly improved in the last few years, and they have been considered a promising alternative to the illumination systems. The main advantages of using LEDs are: high average ;high luminous efficiency; and simple drives, when control and dimming systems are required.It was shown that a high pressure sodium lamp can be substituted by LEDs. Finally, experimental results of LEDs driver and battery charger were presented, in order to validate the proposed system.
X. ACKNOWLEDGEMENT
The members would like to acknowledge . S.P. Gawande for his technical support and Mr. Ganveer (MSEB) for his invaluable support.
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