There are many unreasonable factors in the design of tunnel power supply and distribution system. At present, the power supply system mode commonly used in domestic tunnels is: 10/0. 4kv substation is set at the tunnel entrance, and 0.4kv low-voltage line is used to supply power to the power facilities in the tunnel. . Tunnels powered in this way can sometimes reach a distance of 100m or more. Lower voltage levels and long distance power lines can cause a significant increase in line losses. Most of the transformers currently used for tunnels are S9 or SCg series transformers. The capacity selection in the design is generally referred to the total capacity of all loads in the tunnel and tunnel openings, and certain reservations are considered.
Tunnels, especially long tunnels, have a considerable number of jet fans, but most of these time, these high-power devices are not in operation. The lighting fixtures of the tunnels are usually not fully opened in actual operation due to power saving considerations. It also includes high-power equipment that is not commonly used, such as pumps for firefighting pools in the hole. The contradiction between the selection principle of the above transformer and the actual operation situation causes the transformer to be under the uneconomical operation state of low load for a long time, resulting in a large number of transformer ferromagnetic losses. What's more, in some projects, because the transformer capacity is too large, the percentage of loss is close to the actual power load.
Therefore, the energy saving of the lighting in the tunnel is not simply to switch certain lamps, but to achieve the maximum energy saving based on driving safety. Change the design mode of setting 10/0.4kV substation in the hole at both ends of the long tunnel, and adopt the power supply mode of 10kv medium voltage hole. Medium voltage power supply is a special-purpose power supply facility that has been widely used in long-distance lighting supply for roads, airports, tunnels, etc., with advanced technology and advanced equipment.
Another major factor affecting the design of the brightness in the hole is the brightness outside the hole. The brightness outside the hole is mainly determined by the weather conditions except for the location of the hole. The sunny, cloudy, cloudy and heavy weather has a great impact on the adjustment of the brightness of the population segment, transition section and exit section of the cave. The brightness outside the tunnel increases, and the illumination of each section of the tunnel increases accordingly. Reduced. Rainy weather or windy weather not only affects the brightness outside the tunnel, but also affects the speed of the vehicle. The speed of the vehicle directly affects the length and illumination of each section of the tunnel. In the design of the tunnel lighting, due to the projection of sunlight outside the cave, it can be used as part of the population section to enhance the lighting. With reference to the design specifications, the reinforced lighting fixtures within 10m from the opening can be omitted. In the one-way traffic tunnel, the design of the exit section lighting can be different from the population segment. According to relevant data, it is appropriate to take 60m of the length of the exit section, which can save the high-density lighting of the tens of meters of population. Replaced by lamps that are more sparsely arranged in the middle section.
In conclusion, the energy-saving design of the new tunnel and the energy-saving renovation of the old tunnel still have a lot of room. At the same time, however, there are still many obstacles to seeing the road to energy conservation in tunnels, mainly the traditional design concept and the restrictions on the initial investment of the owner. How to make full use of all reasonable new technologies and break through the old design ideas and construction ideas are issues that highway designers and managers need to seriously consider.
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