Discussion on Key Problems in Application of LED Lighting Technology in Highway Tunnel

The development of highway construction, especially the development of highway construction in mountainous areas, has brought about rapid growth in the scale and length of highway tunnels. According to incomplete statistics, the current construction mileage of highway tunnels in China has exceeded 2,500km. At the same time, the energy consumption of tunnel operations, especially the energy consumption of tunnel lighting, has become more and more prominent, which has a serious impact on the construction of a safe and harmonious traffic environment.

Taking the Huangtatao Expressway and the Liuwu Expressway under the Anhui Provincial Transportation Investment Group Co., Ltd. as an example, the problem can be fully explained.

The Huangtatao (Huangshan-Taling and Xiaohe-Taolin) expressway in Anhui Province is an important part of the National Highway (G3) Expressway and the Hangrui (G56) Expressway. The total length of the route is 51. 3km. 5km且15. 3km。 The starting point to the Xiaohe section length of 17. 5km, the two-way six lanes, the design speed of 100km / h, the roadbed width of 33. 5m; Xiaohe to Taolin and Xiaohe to Taling two sections are 18.5km and 15. 3km 5米。 The two-way four lanes, the design speed of 80km / h, the roadbed width of 24. 5m.

A total of 15 tunnels were set up in the whole line. The total length of the single hole was 28. 3km, accounting for 27.6% of the whole line. If high-pressure sodium lighting system is used, the total power of tunnel lighting fixtures will reach 2,076 kW, the daily electricity consumption will be about 21,000 yuan, and the annual electricity consumption will be about 75.8 million yuan.

The Liuwu Expressway in Anhui Province is an important section of the newly planned Hu Hanrong Expressway (G42). The total length of the route is 90. 9km, which is a two-way four-lane design with a designed speed of 100km/h and a subgrade width of 26m.

A total of 8 tunnels were set up in the whole line. The total length of the single hole was 18.4km, accounting for 10.1% of the whole line. If high-pressure sodium lighting system is used, the total power of tunnel lighting fixtures will reach 1734kW, the daily electricity consumption will be about 17,000 yuan, and the annual electricity consumption will be about 63.30 million yuan.

How to respond to the national call for energy conservation and emission reduction, and maximize energy conservation in tunnel lighting is an urgent problem to be solved in the construction and operation of mountain highways.

1 tunnel energy-saving lighting method

At present, the lamps used in tunnel lighting have high-pressure sodium lamps, fluorescent lamps, high-frequency electrodeless lamps, and LED lamps. Among them, the high-pressure sodium lamp and the fluorescent lamp are based on gas discharge, and the electrodeless lamp is based on a combination of gas discharge and high-frequency electromagnetic induction, and the LED (Light Emitting Diode) is a semiconductor light-emitting diode based on injection electroluminescence.

High-pressure sodium lamp is the main lamp used in highway tunnel lighting in China. However, the new LED lamp has the remarkable advantages of high efficiency, energy saving, long service life, convenient maintenance, wide working voltage range, low working temperature and green environmental protection. It is a powerful competitive product for highway tunnel lighting. Internationally, single-chip high-power white LEDs have matured in technology and standards, and lamps that use them as light sources are mainstream products on the market. The results of this survey and comparison were limited to this type of luminaire (Table 1).


Table 1 Luminaire performance and technical indicators

2 LED energy-saving lighting integration technology

Road tunnel lighting energy-saving technology should reflect integration and originality, focusing on the three links of “environmental energy conservation, mode energy conservation, and energy conservation control”.

(1) Control internal and external environments to achieve basic energy conservation. First, the grasp of the environment outside the cave requires the measurement of the brightness outside the tunnel, the development of external light reduction measures, the verification of the external brightness of the hole after completion, the targeted lighting design and the design correction before implementation, and the effective control of tunnel lighting energy conservation. The outside of the hole. The second is the creation of the environment inside the cave. It is required to combine the interior decoration of the cave and adopt high-reflective materials and self-illuminating materials on the coating in the hole in a segmented manner to achieve a perfect combination of function and form.

(2) Optimize the lighting mode to achieve energy savings at the core layer. Including the choice of illumination source (high-pressure sodium lamp, high-frequency electrodeless lamp, LED lamp, etc.), the choice of lighting mode (tunnel length ≤100m, ≤300m, ≤1000m, >1000m, "no lighting, induced lighting , the standardization of lighting, etc.), the choice of lighting parameters.

(3) Establish a control system to achieve high-end energy conservation. In view of the influence of the brightness outside the hole, the traffic volume in the hole and the speed of the tunnel on the brightness of the hole, the in-hole lighting control system is intended to be stepless control based on the brightness outside the hole and the classification based on the traffic volume and driving speed in the hole. Control composition.

According to the breakthrough research results obtained by the combination of the control system and the LED lighting technology, the stepless control with the brightness outside the hole is realized by the low voltage signal of 0 to 5V. 0V and 5V correspond to the maximum and minimum power of the luminaire, respectively, ie the maximum and minimum illuminance of the luminaire. During the day, the initial system control voltage is set to 5V, and the luminaire is placed at the minimum power state. Thereafter, the system control voltage is correspondingly reduced or increased as the brightness outside the hole increases or decreases, controlling the illuminance of the luminaire and the increase or decrease of the brightness within the hole. Until converted to night lighting mode.

Taking the Huangtatao Expressway as an example, it is estimated that through the “environmental energy conservation” and “mode energy saving” links, tunnel lighting energy saving can be achieved by about 50%. The power consumption is reduced to 1044 kW, which is reduced by 1032 kW, and the annual electricity consumption is about 3.77 million yuan. If you pass the “control energy saving” link, you can further reduce the lighting energy consumption.

3 LED lighting fixtures

The illuminance of the LED luminaire at the appropriate density meets the various sections of the tunnel, especially the brightness requirements of the enhanced section, which is the focus of attention in the application. Among them, the luminous efficiency of LED plays a key role.

(1) LED technology has developed rapidly in recent years, and the luminous efficiency of commercial products has been continuously improved, reaching 100 to 140 Lm/W, which basically breaks through the practical technical bottleneck between high power, high illumination and small volume.

(2) LED lamps use white LED as the light source, and the color rendering index exceeds 80Ra. In practice, lower brightness can achieve the same illumination effect of a light source with a low color rendering index, ie equivalent brightness. For example, the brightness standard of the LED lamp with a color rendering index of 60Ra, the illuminance relative value of 1.6, the color rendering index of 80Ra, and the illuminance relative value of 1.41 can be 1. 41 /1. 6 = 0. 88 times.

4 LED lighting fixture reliability

LED luminaires are still in the experimental stage in highway tunnel lighting. There is no uniform styling product on the market, and the types, organization, structure and standards are uneven. The preliminary results of the research and experiments show that it is necessary to control the quality and structure of the road tunnel LED luminaires for the characteristics of LED technology.

(1) Reliability of LED Module quality. In both cases, the quality of the Led Module is considered unreliable. First, the LED module suddenly fails under normal working conditions. Second, the LED module is severely exposed to light in a short period of time under normal working conditions. It is required to control the source of supply to ensure quality, set standards and implement testing (Figure 1).