1 road lighting settings
1. 1 Road lighting requirements and parameter calculation
Urban roads, especially urban expressways, must be equipped with road lighting.
Road lighting must meet the functional requirements, that is, to ensure safe and smooth road traffic, but also to beautify the urban environment and make the road a beautiful landscape. In order to ensure the quality of road lighting and meet the basic requirements of reliable identification and visual comfort, road lighting should meet the road surface brightness (or illuminance), brightness (or illuminance) uniformity and glare limit.
Road lighting facilities should have good inductivity, and should be safe and reliable, easy to maintain, advanced technology and effective energy saving.
1. 1. 1 Illumination calculation at any point on the road
The illuminance of the luminaire i set on the road surface to any point P of the road surface can be calculated according to formula (1):
EP i=Iγβcos3γ/H2(1)
Where E Pi is the illuminance value of the luminaire i on the P point on the road surface; I γ β is the vertical angle γ and the horizontal angle β of the point corresponding to the light distribution curve or light intensity of the luminaire sample; γ is the light of the luminaire i The angle between the axis and the P point light; β is the angle between the P point and the light source in the horizontal plane; H is the installation height of the lamp i; the illumination is calculated as 1.
Generally, in the road, corresponding to one point, several point light sources have luminous flux at the same point. In the calculation of road design lighting, it is generally only required to calculate the illumination superposition value of 3~4ç› lamps near the point, which will be superimposed. The latter illuminance value is taken as the brightness value of the point, as in the equation (2).
EP =∑EP i(2)
1.1.2 Average illuminance and uniformity
Select a number of representative points according to the width of the pole and the width of the road, and find the illuminance value.
There will inevitably be great and minimal values.
Using equations (3) to (5), the average illuminance E av , uniformity E 0 , and longitudinal uniformity E 1 E av = (∑EP) /n(3)E 0 = E m in / E av(4) can be calculated. E 1 = E m in / E max (5) where n is the number of sampling points taken; E m in is the minimum illuminance in the obtained sampling points; E max is the highest illuminance in the obtained sampling points Value. The more samples are taken, the higher the accuracy of the calculated values.
1. 1. 3 Calculation of brightness index
The formula of the luminance coefficient Q 0 and the illuminance conversion coefficient P 0 : Q 0 = L / E; P 0 = E / L =1 / Q 0 (6) where Q 0 is the luminance coefficient of the road surface; P 0 is the road surface Illumination conversion factor; L is the brightness value of a unit on the road surface; E is the illumination value of a unit on the road surface.
Equation (6) can be used to calculate the road surface brightness (7): L = Q 0 E = E / P 0 (7) The brightness coefficient is determined by the material properties of the road surface, the light source, the light environment and the observer relative to the observation unit. position.
The P 0 value of cement road and asphalt pavement in China's highway industry is 15 and 21; in the tunnel, it is changed to 13 and 22.
1. 2 road lighting settings
1. 2. 1 illuminance standard
When determining road lighting standards, consider the nature of the road, the grade, the amount of traffic, and the reflectivity of the road. The current "Urban Road Lighting Design Standards" < 2 > (CJJ 45-91) was released in 1991, in which the design illuminance standards are lower than the current level of domestic economic development and the level of the Shenzhen Special Economic Zone. Therefore, the conventional practice in Shenzhen is to design the design illumination standard one or two levels higher than the current urban road lighting standard.
1. 2. 2 main lane lighting settings
The illuminator is installed above the lane through the pole, and the poles are arranged along the lane line at regular intervals. Reasonable choice of pole structure, luminaire model and layout, the road will be well illuminated.
The pole illuminators are available in single and double sides, one side mounted on the hard shoulder and the double side mounted on the central split belt boss. The feature dimensions of the structure are post height, cantilever length, and cantilever elevation.
Increasing the height of the pole can increase the illumination area, and the number of illuminators can be relatively reduced. The uniformity can be appropriately improved, and the glare can be suppressed to a certain extent, thereby improving the lighting comfort. However, too high a pole will reduce the average illuminance, increase the luminous flux outside the escape shoulder, and increase the cost.
At present, the commonly used pole height is about 10-15 m.
Increasing the length of the cantilever can increase the length of the illuminator into the lane, increase the luminous flux received by the lane, increase the average brightness of the road surface, and reduce the luminous flux of the shoulder or emergency stop belt, and the excessively long cantilever must increase the structural strength. Therefore, the length of the cantilever needs to be optimized. C m的范围内。 CIE, the length of the cantilever is not more than 1 / 4 of the height of the bar. Currently, the commonly used value is in the range of 1. 5 ~ 3. 0 m.
The elevation angle of the cantilever increases the lateral illumination range of the illuminator at a certain installation height to the road surface. Increasing the elevation angle too much does not make the road surface brightness adapt to the increase, and the glare is more likely to occur in the curve. China's specified elevation angle does not exceed 15 °, CIE recommends that the elevation angle is controlled within 5 °.
1. 2. 3 illuminator installation size
The recommended value of the mounting height of the pole type luminaire when it is installed.
2 urban road lighting energy saving measures
According to the test statistics, the energy consumption of the sodium lamp is nearly double that of the high-pressure mercury lamp, and the installation method of the double-sided lamp splitting belt is obviously superior to the one-sided installation. Street lighting is currently powered by the urban grid, so its voltage fluctuates as the grid voltage rises and falls. Especially in the latter half of the night, the power load is reduced, and the voltage of the low-voltage power grid is increased, which makes the street lamp extremely bright and dazzling, resulting in excessive illumination, which not only greatly increases power consumption, but also causes the actual service life of the light source and the electrical appliance to rapidly decrease, and the number is greatly increased. Maintenance and maintenance costs. In order to make the city more scientific and brighter, the use of street lighting intelligent control is one of the more applicable technologies. The specific feasible energy saving measures are described as follows:
2. 1 Determine reasonable lighting standards
When formulating road lighting standards, it is necessary to first determine the road lighting level and design according to different lighting places such as main roads, secondary roads and residential quarters in order to maximize the use of light energy. It is usually possible to make several schemes for analysis and comparison, and to select a scheme that is both economical and energy efficient.
2. 2 select a good light source
On the basis of proper consideration of the color rendering of the bulb, the use of high-efficiency light source is an important part of lighting energy saving. Incandescent lamps are often used as the first generation of light sources. Fluorescent lamps and high-pressure mercury lamps invented in the 1930s as second-generation light sources. In the mid-1960s, after the translucent alumina ceramics and its sealing process were broken, the emergence of high-pressure sodium lamps was hailed as the third-generation light source. High pressure sodium lamps are high intensity gas discharges. The highest light efficiency of the lamp can reach 140 lm / W, which is 2.2 times that of the high pressure mercury lamp and 8 to 10 times that of the incandescent lamp. Replacing incandescent lamps with high-pressure sodium lamps can save more than 80% of electricity. Instead of high-pressure mercury lamps, it can save about 60% of electricity, and the characteristics of high-pressure sodium lamps are stable, the maintenance of light flux is best, the maintenance factor is high, the service life is long, and there is no Corrosion, strong light transmission and other advantages, high-pressure sodium lamp has become a widely used and energy-saving light source, the attention of the energy sector and lighting designers.
2. 3 scientific control switch time
Whether the public lighting opening and closing time is accurate or not is also a major aspect of lighting energy saving. Taking the road as an example, the installed capacity of a city has a statistical value of 700 kW at the end of 1997. If the opening and closing time is accurately controlled, it is calculated to be less than 5 minutes per day, and the annual electricity saving is about 21 280 kW h. Therefore, reasonable control of the opening and closing time of the street lamp can effectively save energy. For example, manual control, clock control, photoelectric control, and microcomputer control are used to control the illumination time. In addition, the lighting control method can also adopt energy-saving measures, such as the implementation of the midnight light, that is, when the night is quiet, the pedestrians on the road are scarce, and some of the lights can be automatically extinguished. If there are several rows, the rows are extinguished or the lights are turned off. Appropriately reduce the illumination and reduce the power consumption, which requires the designer to consider the various factors such as the control of the midnight light and the laying of the line during the design.
2. 4 reduce the reactive power loss and reduce the power supply radius
Now with the continuous improvement of power supply quality, the grid voltage is becoming more stable and normal, and when the power consumption is significantly reduced in the middle of the night, the power supply voltage rises more, and the power consumption of the lighting power consumption also increases. This not only shortens the life of the light source, but also increases unnecessary energy consumption.
Now the relevant unit has developed an energy-saving device, which is installed in the lighting line and can be automatically put into operation according to the voltage value set by the user. When the grid voltage is lower than the set voltage, the load voltage is directly supplied by the grid, and the economizer does not participate in the work. When the voltage is higher than the set voltage, the economizer is automatically put into operation, and the grid voltage is stepped down by the economizer to supply the load, so that the lighting device always operates at the rated voltage. Moreover, the energy loss of the economizer itself is extremely small, which also saves the power consumption of the lighting device.
In addition, when selecting the cross-sectional area of ​​the conductor in the street lamp pipeline, the loss of the length of the line should be considered, and a reasonable power supply point should be selected. The power supply radius should not exceed 500-800 m, reducing the power loss of the line.
2. 5 Reasonable selection of lamps for regular maintenance
The main function of the luminaire is to distribute the luminous flux of the light source to the desired direction to improve the utilization of light and avoid glare. The efficiency of a luminaire refers to its utilization of the luminous flux of the source. The luminous flux of a luminaire made of any material is always <1 for the luminous flux of the light source when it is reflected and transmitted. Assuming a light source of the same power, a luminaire with a higher efficiency, 70% to 80% of the luminous flux. It is used, and the other is equipped with a lower efficiency lamp, and the luminous flux is only 40% to 50%. In comparison, the low-efficiency luminaires consume nearly 30% of the power consumed by their light sources, which is often overlooked. Therefore, when selecting a luminaire, try to choose a luminaire with a good light distribution curve and high efficiency. Generally, high-efficiency lamps use high-reflectivity materials and advanced processes, such as high-purity aluminum plates using electro-polished polishing, protective covers with good light transmission properties, etc.; the sealing performance of lamps is good, waterproof and dustproof, and light is reduced as much as possible. Loss.
The luminaire is inevitably polluted during use, such as aluminum oxidation of the reflector, dust and dirt inside and outside the shield, etc., which will inevitably cause loss of light. If it is not regularly maintained, the same as above, that is, the light source Most of the power consumed is wasted. The cleaning of the lamp should be wiped at least 2 times/a, and it needs to be thoroughly cleaned to ensure its transparency, effectively improve the utilization of the light flux of the light source, reduce the loss of light, and improve the illumination.
3 Conclusion
A good lighting system is closely related to a good lighting fixture and its arrangement; an energy efficient lighting system is closely related to good lighting design, and good lighting design and precise lighting calculations are closely related. When designing road lighting, the designer should minimize the energy consumption of road lighting under the premise of ensuring that the road lighting effect meets the corresponding standards, so as to achieve "effective lighting and energy saving", so that China's energy is effectively Use, while ensuring the safety and smoothness of urban road driving.
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