Lighting design of road tunnel

With the rapid extension of highway construction in China, the power resources are scarce in the complex terrain and sparsely populated areas, and the problem of huge power costs is becoming more and more prominent, especially the power supply problem of highway tunnel lighting systems is becoming more serious. According to national regulations, road tunnels above 400m

It is necessary to set up lighting facilities. Therefore, it is very urgent to develop a road tunnel solar lighting system that can reduce the cost of construction and reduce the cost of operation and management. It is very urgent to understand the current situation of the use of road tunnel lighting systems at home and abroad. It has important guiding significance for the development of road tunnel solar lighting systems.

1 Development of highway tunnel lighting and current status of tunnel lighting design

At present, the road tunnels built and under construction in the country have reached more than 1,000 km and are still in rapid development. However, there are very few lighting systems installed in road tunnels. Most of them do not have lighting or lighting systems, but they are not used. Therefore, the lighting quality is very low.

1.1 road team road lighting

The development of highway tunnel lighting fixtures in China started late and the foundation is poor. Especially for the deep-human research on the requirements and characteristics of tunnel lighting fixtures, there is a great gap between the design and manufacture of lamps and lamps. In recent years, although a few units such as Fudan University, Shanghai Lighting Research Institute, Chongqing Transportation Research and Design Institute, and Zhejiang Transportation Planning and Design Institute have corresponding research conditions and certain test equipment, they attach great importance to tunnel lighting research. However, most lighting manufacturers Without the research conditions and test equipment for highway tunnel luminaires, the ability to independently develop tunnel luminaires is poor. Domestic tunnel lighting factories are mostly small factories or mainly engaged in the production of lighting equipment in other fields. The technology, technology and equipment are backward, the production is scattered, the level of specialization is low, and the benefits are not high.

In addition, there is a lack of sufficient knowledge and necessary investment in the development of highway tunnel lighting. Compared with the concentration of foreign lighting electrical industry production, it is far from the economic scale. Most of the tunnel lamps used in China have problems such as narrow optical band, insufficient light distribution quality, high energy consumption, poor quality stability, short life, and low grade. This directly leads to poor lighting effect of highway tunnels, which cannot meet the requirements of highway tunnel lighting and seriously affects Driving safety.

1.2 tunnel lighting design

The light source of the tunnel illumination should meet the requirements of light efficiency, luminous flux, life, light color and color rendering under the specific environment of the tunnel, and at the same time ensure good visibility in the smoke formed by the vehicle. The effect of tunnel lighting must be achieved by relying on a reliable light source. Once the road tunnel is used, the lighting system is almost in a long-term state under normal conditions. Therefore, choosing a suitable light source is an important part of tunnel lighting.

Highway tunnel lighting is usually designed according to the current regulations. The tunnel is divided into a population section, a transition section, a middle section and an exit section. There are two transition sections, which are designed before and after the middle section. The length and illuminance of each section are designed from the requirements of driving safety throughout the year. The design of the maximum illumination in the cave is to determine the lamp power and the distribution density of the lamps in each section of the tunnel with the maximum brightness and maximum speed of the year. The automatic lighting control achieved is also very limited. Usually, due to the limitation of the circuit wiring loop, only 2~3 levels of manual or automatic control can be achieved. For parameters such as weather, speed, traffic flow, etc., only the maximum value is considered during the design phase. Finally, the length and illuminance of each segment of illumination are always at their maximum. Due to the use of time-varying parameters such as weather, vehicle speed, and traffic flow, it is impossible to adjust the control of the entire tunnel lighting system in an adaptive manner. Therefore, from this point of view, there is a large amount of power waste problem in the conventional design and use of tunnel lighting systems.

2 lighting system solution

2.1 circuit design

In the circuit design process, the integrated voltage source, voltage influence, brightness level, illumination stability and other factors are integrated to study the reasonable matching circuit to achieve the purpose of reducing power consumption and improving light efficiency.

Study protection circuits to reduce multi-point damage caused by series and parallel LEDs. LED dot matrix layout is an array of multiple LEDs connected in series and in parallel. In the course of use, as long as one LED is shorted or open, the whole or multiple LEDs will be extinguished.

Analyze the rationality of circuit design and circuit layout, and study the heat dissipation method to improve the service life of LEDs and keep them in good working condition. The LED die junction temperature exceeds the standard limit value, which will cause the irreversible light intensity to decay. In order to solve this problem, research is carried out from the circuit design and layout, and a reasonable design scheme is proposed to promote the LED to maintain a good working condition and prolong the service life.

Study the influence of AC/DC power supply on LED and choose the appropriate power supply mode. LED power supply mode is different, it will affect its performance, especially the AC power supply itself has frequency conversion, which is easy to cause LED flashing. Therefore, choosing the right LED can improve the lighting effect.

Study the appropriate drive circuit to prevent burning of some of the LEDs. The LED dot matrix is ​​composed of a plurality of LED tubes. In use, occasionally, some LEDs are burned due to energy concentration, and a suitable driving circuit can alleviate the occurrence of related phenomena to a certain extent.

Improvement on the circuit not only solves the heat dissipation problem, but also reduces the working current by nearly 10mA compared with the original design. The power of the entire highway tunnel lighting unit is about 6W, which reduces the power consumption, thus making the road tunnel lighting solar power supply system low-cost application. become possible.

2.2 Lighting design

Lighting fixtures are appliances that transmit, distribute, and change the distribution of light sources, including all components required to secure and protect the light source, except the light source, and the wiring accessories necessary to connect to the power source. Due to different requirements for lamps in different places (such as in highway tunnels, lamps are required to have strong corrosion resistance, not easy to age, moisture, and jets), therefore, lighting fixtures must be designed from three aspects: Solve the convenience of board installation and disassembly; on the other hand, design for routing, heat dissipation and moisture resistance; finally, the choice of light-transmitting materials. Therefore, the developed lighting fixture can achieve the level of safety protection, good heat dissipation, convenient disassembly, and meet the requirements of use.

2.3 Solar power system design

Photovoltaic power generation is realized according to local solar energy resources. At the same time, the lighting system is intelligently controlled to reduce power consumption, thus laying a foundation for solving the serious power loss problem of the solar power supply system in a certain period of time.

The solar power supply system mainly includes a photovoltaic module (array), a battery, an inverter, and a controller.

The photovoltaic module is a device for converting solar energy into electrical energy; the junction box is a wiring for summarizing the solar battery components, and is equipped with a lightning arrester, a backflow preventer and a switch, etc. • The charging controller is an overcharge protection device of the battery; the inverter The direct current is converted into 220V 50Hz alternating current, and the input voltage control and overload protection device are built in; the storage battery is an electric energy storage device.

In the research of road tunnel solar lighting system, the lighting system is powered by DC 220V. Therefore, its power supply system does not require an inverter for direct AC conversion. When selecting a solar cell module, it requires a certain nominal operating current, output power, and a working life of 20-30 years. It must have sufficient mechanical strength to withstand the conflicts, vibrations, and other phenomena that occur during transportation, installation, and use. Stress, combined loss of electrical performance is small, and cost is low.

3 problems and measures of highway lighting system

(1) LED lighting attenuation problem

Lighting attenuation is the main problem that needs to be solved in the future promotion, which will directly affect the application cost. There are three main reasons for the attenuation problem of LED lighting: LED's own performance impact; lighting fixture pollution; lighting circuit has certain defects.

In order to solve these problems and improve the service life of road tunnel LED lighting, the following points should be made: Firstly, through the continuous experiment, observation and comparison in the application, select the LED product that is most suitable for the road tunnel lighting system; then, pass Observe the change of illuminance, eliminate other factors that cause attenuation, determine the decay period of LED illumination brightness caused by pollution, and perform regular cleaning. Finally, through the continuous improvement of circuits such as heat dissipation and steady current, maintain LED stability and improve service life. .

The LED die junction temperature exceeds the standard limit value, which will cause the irreversible light intensity to decay. In order to solve this problem, starting from the circuit design and layout, a reasonable design scheme is proposed to promote the LED to maintain a good working condition and prolong the service life of the LED. In addition, an intelligent control system is used to control the lighting time of the LED, thereby extending Its use time.

(2) Intelligent control system

The intelligent control system directly affects the matching of the solar power supply system and affects its construction cost. Compared with high-pressure sodium lamps, LED lighting can reduce power consumption of nearly 60% of road tunnel solar lighting systems and reduce the cost of solar power systems. However, in order to realize the further promotion and application of the road tunnel solar lighting system, it is necessary to further reduce the use cost, improve the control time and object of the intelligent control system, and organically combine and control with the solar power supply system, thereby reducing the electricity cost of the highway tunnel lighting system. And reduce the cost of the power supply system, thus laying a solid foundation for reducing construction costs.

(3) Road tunnel solar lighting system lacks uniform standard illuminance values ​​for different road grade LED illumination sources,

The development of standards such as optimal spacing and LED light source device selection will affect the service life of lighting fixtures and affect the reasonable matching of solar power systems. At present, there is no uniform standard in China, and it is impossible to measure whether LED lighting fixtures meet the lighting requirements.