Da Nang City, the first-class city of Viet Nam, is the main city in Central Vietnam and the Western Highlands, located on the strategic position of the East-West Economic Corridor (EWEC) and supplies high class services for the whole region…It is also the city which catches the attention of foreign and domestic investors. Thus, it must have a lighting system adequate to the standard of the management and engineering; besides, it needs to obtain the advanced, safety, saving and effective technology in term of the economy.
In our country, the investment on the public lighting system, which is defined to serve for the public good, is the essential demand and reflects the urban development. The proper investment in the quality of the public lighting system will create a motivation to improve the management efficiency following advanced standards in the world. Then, the public lighting system, together with other infrastructure systems, will contribute to the current urban solutions with the aim of building the civilized and modernized Da Nang City.
The construction of an effective and energy saving public lighting system in Da Nang City should satisfy the following standards:
- Advanced Technology
The focus on applying advanced technology, not necessary the most advanced, is to concentrate on its compatibility with the current facilities of the public lighting system, ensure the stable operation of the system and facilitate communication contact as well as finding the sources of its alternative commodities and components.
Energy saving in public lighting system does not simply mean to switch off the lights when needed, but it is necessary to apply synchronously the advanced technological solutions, effectively use energy saving lighting resources and facilities following the guideline of "consuming less electrical energy, but obtaining better quality of light source" in order to satisfy the demand of using as well as reducing electrical energy of the public lighting system in both the urban and suburb areas, especially at nightly peak hours.
Therefore, to realize the above standards, it is necessary to carry out the following solutions:
II. The solution of improving management ability:
Applying mobile communication technology (GMS/GPRS) to the control, supervision and management of the public lighting system:
a/ Constructing the controlling center of the public lighting system:
Comparing to centrally governed cities with the same population such as Hai Phong and Can Tho, Da Nang has larger covering of the public lighting system, which is 2.8 times as large as Can Tho and twice as large as Hai Phong. It is surely a strong point showing the fast infrastructure development of a main city in Central Vietnam and the Western Highlands.
Additionally, together with the strong economic and tourist growth during the last few years, Da Nang has impressed visitors and the locals with the image of a modern and civilized city. The appearance of annual festivals such as International Fireworks Competition, International Gliding Competition, of architectural works such as bridges crossing the Han River, including Thuan Phuoc Bridge, Han River Bridge, the Dragon Bridge, etc… and of central streets with a plenty of luxury shops and restaurants along both sides of the Han River has created bigger demands of the management concentration, the automation and the energy saving for the public lighting system.
Furthermore, due to the orientation of the Vietnamese Government on the development of public lighting system, the Prime Minister issued the Decision No. 1874/QD-TTg on October 11, 2010 on approving the developing orientation of Vietnamese cities' public lighting system to the year 2025. It is the newest document defining that the public lighting system of special, first-class and second-class cities must be managed and controlled by the controlling center by the year 2015.
Thus, there is a little time from now till 2015, and all of the reasons above are the appropriate and reasonable motivation for equipping a controlling center of the public lighting system, firstly for Hai Chau District, and then for neighboring districts in a near future, and lastly for suburban districts.
b/ Functions of the controlling center:
In order to improve the quality of the lighting system, it is urgent and necessary to invest in building a Danang Controlling Center of the Public Lighting System with the following functions:
- Controlling, supervising and managing each electric box and each lighting spot at any time.
- Improving the lighting quality for the light-lines, ensuring the connection of the network with controlling centers and accessing to media communications easily.
- Saving the operating cost of the system: electricity consuming cost, maintenance cost, and the installation cost, which is the specific aim of the system.
- Creating the basis for carrying out an effective maintenance regulation which is able to predict the degradation of the system, future damages in the future and to give the immediate warnings about technical problems.
c/ Technological solutions:
In order to gain the goals above, the selected technological solution is supposed to be the plan of controlling electric boxes combining with the light spots, which is based on the mobile communication method of GMS/GPRS to access to the following activities through the controlling center:
- Controlling on-off systems.
- Adjusting the reducing regime from afar.
- Controlling the soft start-up system
- Stabilizing the input voltage of the lights
- Updating and managing the data.
- Checking each lighting spot.
d/ Economic effectiveness:
This is the biggest and most obvious saving part of the public lighting system. It helps to save the consuming electricity thanks to the advanced technological application of stabilizing the voltage, maintaining the stability of the luminosity, saving in short-term and long-term, saving in conformity with general regulation, and actively switching on/off the lights in accordance with the luminosity in the open air.
v Saving thanks to stabilizing the working voltage:
Due to the application of modern technology and the use of the new model of electromagnetic voltage regulator with the main function of stabilizing and adjusting the output voltage of the appliance, which ensures the optimal operating parameters (such as the voltage, the capacity or cosj) for the voltage source of the public lighting system and gets rid of too highly starting-up power from lighting boxes.
v Saving thanks to diminishing to maintain the stable luminosity over time and space
In the process of the efficient operation, the luminous flux of light bulbs will decline depending on the time of consumption. This makes the illumination of the lights on the roads changes over time as well as creating the dark or bright spots of the whole line of light when the light-bulbs which are gone out have been changed before the time of their expiry date.
The new technology allows lowering the luminous flux level of newly-used light-bulbs and raising the luminous flux level over time. It also makes the luminous flux of the newly changed light bulb symmetrize in conformity with the whole light-lines' luminous flux. Therefore, the quality of the illumination is always stable over time and space.
v Saving due to the decrease of operation system when the flow of vehicles reduces:
During the lighting time, the flow of vehicles on the routes is changing too much so the illumination on the routes is also different. The new technology allows lowering the illumination on the streets following the optional time for the areas with high traffic density, the areas with average traffic density and the areas with low traffic density. This reducing solution is more optimal than the solution of phase reduction or the alternate solution of light bulb reduction by turning on two light bulbs and turning off one light bulbs or vice versa.
v Saving due to turning the lights on/off accurately depending on the outdoor illumination:
For the public lighting system, the time of turning the lights on/off is accurate and synchronous if being controlled and supervised by the controlling center. Then, the problem of leaving the lights on in daylight and off before sunrise can be avoided.
Da Nang City at night
III. The application of the light source and the illuminating appliances in the public lighting system:
To construct an effective and energy saving public lighting system, apart from the installment of the controlling center, new technological appliances must be gradually used to replace the old ones.
1.Installing reducing appliances:
The appliances are supposed to ensure all the electric saving functions:
§ The capability of adjusting the output accurately
§ Smart start-up, which is the control over the start-up during nightly operation,
§ The assurance of the cycle of turning on/off the lights all year round.
§ Diverse operating modes including smart start-up, normal and energy saving (slight decrease, deep decrease…)
2.The using of LED lights in the public lighting system:
Nowadays, in many countries, LED (Light Emitting Diode) is commonly applied in various fields including the field of lighting due to its effectiveness on saving energy.
The considerable advantages of LED bulbs can be recapitulated as follows:
- Saving energy much more than other bulbs like incandescent bulbs, halogen bulbs and fluorescent bulbs.
-Being eco-friendly and reducing the amount of CO2
-Having long-lasting lifespan, from 50,000 up to max.100,000 hours
-LED bulb lighting is human-friendly since it minimalizes the ultraviolet ray and the infrared radiation, and does not causes blinking light or eye troubles.
-LEDs radiate low heat during its operating process.
Although the current starting cost of LED bulbs is high, generally, the advantages of LED bulbs are outstanding, together with the global trend in its applications. Currently, the applications of LED in the public lighting system include:
- Lighting streets.
- Lighting architectural works.
-Lighting decorative works, festivals and arts: colorful and diverse LED bulbs which are easy to change electrical capacity and to be controlled are reasonable for saving the electricity consumption.
- Lighting traffic, advertising and optical warning signs.
Currently, Da Nang City is applying LED to the public lighting system, in which is the lighting of decorative works, festivals, arts and alleys develops relatively rapidly, the lighting of architectural works is not so common, particularly, the street lighting is still in the experimental stage. Thus, in constructing an effective and energy saving public lighting system, it is vital that the application of LED technology should be deployed more and more quickly. Furthermore, it can be said that LED technology has been developing rapidly, and in the lighting market, LED bulbs are gradually replacing lighting appliances of traditional technology, and taking an important role in the public lighting system.
Art lighting on Han River Bridge
3. The using of the lights with two-level productivity ballasts:
Currently, Da Nang City is using two-level productivity ballasts for nine lighting routes with the total number of various kinds of 770 high-voltage lighting sets in order to replace the forced reducing of some lights at night to save the electricity. The main advantage of this kind of electrical ballast is to contribute to the saving of electric consumption for the public lighting system, which reduces 30% of electric consumption per bulb, equally separates the lighting intension into its constituent parts, intensifies the lifespan of the bulbs and the ballasts, eliminates the inadequate situation of forcedly cutting out the additional charge of the public lighting system, decreases a significant amount of CO2. However, the most disadvantage is that the price of two-level productivity ballasts is more expensive than one-level productivity ballasts due to the increase of material expenditures and laborers. But, for the long term, the using of two-level productivity ballasts is mainly advantageous and they need to be installed widely.
4. The using of clean energy (wind energy, solar energy):
Nowadays, traditional energy sources become the urgent matter of every country all over the world. Since the oil and gas have become more and more exhausted, scientists are trying to find out new energies. Moreover, the problem of the polluted environment, the greenhouse effect, the ozone layer and the lessening of the earth's green lungs make the scientists take notice of the "clean" element of new energies. From that, people taking responsibility for lighting works need to research into the application of wind energy and solar energy.
Currently, solar lights for the public lighting system have been installed as an experiment in Da Nang City while some big cities are using solar lights to replace traditional lights of the public lighting system.
In order to avoid the expensive cost for investing in the construction of electric source supply from the national electric network and to contribute to the saving of energy, clean energy sources should have been exploited in Da Nang City as soon as possible.
Saving energy is one of the Party and Government's important policies, which needs to be wholly comprehended, effectively campaigned and carried out in all levels and branches of government, organizations and citizens including those who are in charge of public lighting system.
The situation of energy exhaustion will soon be the problem in the world as well as in our country, so managing and utilizing energy, including electric energy, wastefully and uneconomically will affect significantly the social manufacture and consumption.
Therefore, from now till 2015, a controlling center of public lighting system should be built; meanwhile, new energy sources should be used to replace traditional lighting sources so as to build an effective, eco-friendly and energy saving public lighting system. This is the most vital and imperative action which needs the help of the city authorities.