Energy saving measures for urban street lighting

1. Reasons for the high electricity bills First of all, the main purpose of road lighting is to make vehicles and pedestrians travel safely. The main purpose of outdoor lighting is to beautify the city night scene and let the citizens have a harmonious and warm leisure atmosphere. The flow of people and vehicles has been significantly reduced after 12 o'clock in the evening. At this time, the power consumption is at a low point, the grid voltage rises, and the light bulbs are brighter than in the middle of the night. Therefore, the light utilization rate during this period is quite low. If you do not take measures, you can adjust it at any time Illumination, will waste a lot of electricity. Secondly, the road lighting is directly connected to the commercial power grid. According to the test, the output voltage of the transformer at each power supply point is much greater than the rated voltage of 220V, and some are as high as 250V or more, which greatly increases the output power. Third, due to the improper selection of lamps and light sources, the luminous efficiency produced by consuming the same amount of electric energy is significantly reduced, and the material and size of the cable directly affect the loss of the power supply line. In addition, inductive ballasts are mainly used at present. Due to insufficient attention to reactive power compensation, reactive power has increased significantly. 2. Energy-saving measures 1. Under the premise of ensuring functions and effects, reasonably adjust the number and time of lighting. Road lighting should be fully promoted in the middle of the night, and the primary and secondary trunk roads should be powered by double circuits, which are divided into the full-night light circuit and the midnight light circuit. If a special midnight light circuit is provided unconditionally, the single-phase midnight power supply can be used, but the whole transformer should be kept in three-phase balance; Branch roads, roads in industrial areas and living areas, and streets with narrower road widths adopt the unilateral light changing method in the middle of the night. City lights are generally only turned on during the hours when citizens have more outdoor activities. 2. Choose a light source with high luminous efficiency. The energy saving of the light source mainly depends on its luminous efficiency, but the selection of the light source should not be based solely on the luminous efficiency, but should be reasonably used according to the comprehensive consideration of the color rendering index, service life, and startup characteristics. Principles for selecting light sources: minimize the use of incandescent lamps; promote the use of thin tube fluorescent lamps and compact fluorescent lamps; gradually reduce the use of high-pressure mercury lamps, especially self-ballasted high-pressure mercury lamps should not be used arbitrarily; actively promote high-pressure sodium lamps ,Metal halide lamp. 3. Select high-quality and efficient lamps and lanterns. The performance of lamps and lanterns is crucial to energy saving, mainly the effect of lamp efficiency and light distribution. The luminaire efficiency is the ratio of the luminous flux FL emitted by the lighting fixture to the total luminous flux FS emitted when all the light sources in the luminaire are ignited outside the luminaire under specified conditions, expressed by h, that is, hu003dFL/FS. Generally speaking, h is proportional to the reflectance and transmittance of the lampshade material, and the efficiency of an open lamp depends on the ratio of the opening area S0 of the lamp to the reflection area S and the shape of the reflector. In order to minimize the loss of light in the luminaire, the larger the S0/S, the better. The shape of the reflector mainly causes the light to be reflected multiple times within the lampshade. Therefore, the selection of lamps should consider the following aspects: should have a high utilization factor; reasonably choose the light distribution of lamps; give priority to block-type lamps; try to choose lamps without accessories; try to choose lamps with high retention rate. 4. Detect and adjust the output voltage of all transformers to make the output voltage the rated value. If it cannot be adjusted down, the motor-saving can be used to reduce the voltage and save energy. After testing, the power saving rate of saving motor is between 11% and 23%. 5. The reactive power compensation of the circuit can be done in two ways: single lamp compensation and centralized compensation. Single lamp compensation is to connect a capacitor with appropriate capacitance in parallel to each lamp for compensation, which not only reduces the reactive power of the lighting circuit, but also reduces the power loss and voltage loss on the low-voltage lighting circuit. At the same time, because the line current is reduced, a wire with a smaller cross-section can be selected. The empirical value of single lamp compensation: 250, 400W high pressure sodium lamp compensation capacitor capacitance value is 30, 50UF respectively. The centralized compensation is to install the capacitors in the power distribution device in a centralized manner. In addition, discharge equipment must be installed. 6. Promote the use of electronic ballasts. The electronic ballast is an AC-DC-AC converter, which converts the 50HZ alternating current into a stable direct current after being rectified and filtered, and then converts the direct current into a high-frequency current as the lamp current. Since the gas discharge lamp has a negative volt-ampere characteristic, it becomes a positive volt-ampere characteristic in a high frequency state, so that the light bulb can be started normally. Compared with the inductive ballast, it has the following advantages: the energy consumption of the inductive ballast is 10% to 15% of the light bulb, the energy consumption of the electronic ballast is extremely low, and it has the characteristics of constant power output. 7. Ensure that the three-phase power consumption of the transformer is basically balanced. If the three-phase current is unbalanced, the line loss will be increased. Assuming that the current of each phase is I and the wire resistance is R when the three phases are balanced, the line loss is W1u003d312R; if the three-phase currents are unbalanced, respectively I, 1.5I, and 0.5I, then W2u003d12R+(1.5I)2R+ (0.5I)2Ru003d3.512R, obviously the line loss increases. 8. Reduce the loss on the power supply line. According to the formula Su003dI/In [where S is the cable cross-sectional area (mm2), I is the street lamp load current (A), and In is the economic current density (A/mm2)] select the cable cross-section to make the resistance a reasonable value, so that Reduce line loss. 9. Select high-tech energy-saving products, such as motor-saving, adjustable voltage electronic ballasts, microcomputer street lamp power-saving instruments, single-lamp power supply controllers, etc.