First, active energy-saving technology
Active energy saving technology
SCR chopper technology. The principle is to control the conduction angle of the thyristor to cut off a part of the sine wave voltage input to the grid, thereby reducing the average value of the output voltage and achieving the purpose of voltage regulation and power saving. The energy-saving regulating device can accurately control the output voltage in real time for the lighting system, meet the optimal value of the lighting power, and adjust the voltage speed, high precision, real-time adjustment in time-division, voltage regulation, and electronic use The components are relatively small in size, light in equipment, and low in cost.
However, this regulation method has fatal flaws. Since the chopping voltage cannot achieve sine wave output, a large number of harmonics will appear, which is extremely harmful to the harmonic pollution of the power grid system, so it should not be used in circuits with capacitance compensation. In particular, the high-power thyristor chopper-type power-saving equipment itself has the drawback of harmonic pollution, which not only shortens the service life of the power capacitor but also increases the copper consumption and iron consumption of the transformer, reduces the actual use capacity of the transformer, and increases the reactive power loss. It wastes electric energy. In severe cases, it also causes overheating of electrical equipment, causing malfunctions or other hazards of electrical equipment such as switches and contactors. At present, in foreign developed countries, electrical equipment that limits harmonic content exceeding the standard has been explicitly incorporated into the network.
Auto-coupled buck regulation technology. The principle is that through an autotransformer movement, according to the input voltage level, different fixed transformer taps are connected, and the grid voltage is reduced by several steps such as 5, 10, 15, and 20V to achieve the purpose of buck power saving. Overcoming the defects of harmonic generation by the thyristor chopper type device and realizing the sine wave output of the voltage. This kind of power-saving facility can only fix the voltage drop, can not be boosted and regulated, and can not achieve automatic and precise control of the voltage. Especially when the grid voltage fluctuates, the output voltage of the regulating device also fluctuates up and down, causing the operating voltage of the lighting facility to be in an unstable state, and the protection effect on the electric light source cannot be achieved. When the grid voltage rises, the power saving rate is not the best state, and when the grid is lowered, the undervoltage phenomenon may occur, causing the light source to fail to light normally, and instead reducing the life of the light source, which is the defect of such a power saving facility.
Microcomputer control technology. The principle is to use microcomputer control technology, the system collects the output and input voltage signals in real time, compares with the optimal illumination voltage, and automatically adjusts by calculation to ensure the optimal output of the lighting system.
Its technical characteristics are: 1. Using microcomputer technology and high reliability software and hardware design to achieve intelligent control process. 2. For the phenomenon of high voltage and fluctuation of power grid, real-time dynamic tracking of online power supply, continuous adjustment of current, regulation and output of optimal lighting voltage and power, realization of stable working voltage, reduction of working current, improvement of power quality, saving of lighting power . 3. Multi-time energy-saving operation. According to the user's actual lighting needs, through the program multi-time energy-saving voltage setting, to meet the user's demand for different light sources, different time, to achieve the best lighting state and maximum power saving rate. 4. Realize the soft start and slow ramp control process of the light source. Due to the use of low-voltage soft start for full preheating, the impact of the starting current can be reduced, and the life of the light source can be effectively improved. In the process of voltage regulation and voltage regulation, the intelligent regulation device adopts the slow ramp mode to make the voltage slowly transition within the set time, ensuring that the light source is not affected by voltage and current, reducing the damage to the electric light source and prolonging the service life. 5. Realize sine wave output, no harmonic pollution to the power grid, strong impact on surge voltage and transient large load. Although the implementation cost of this type of lighting energy-saving technology is slightly higher than the first two, it can achieve intelligent lighting control, effectively protect the electric light source, reduce power consumption, and save energy, so the economy and reliability are far better than the first two. A kind of active energy-saving technology is a mature lighting power-saving technology at home and abroad.
Second, reactive energy saving technology
Reactive power, like active power, is an integral part of ensuring power quality. The power system should ensure the balance of reactive power, otherwise it will cause increased line loss, voltage drop, power factor drop, and even equipment damage. In road lighting, interest rate electricity and additional electricity (reactive loss penalty) caused by reactive power loss account for about 20% of the total electricity cost. It can be seen that adding reactive power compensation equipment and improving the power factor of the network plays an extremely important role in the power grid's loss reduction, power saving and safe operation of the equipment.
At present, there are three kinds of reactive energy-saving technologies in road lighting: capacitor single lamp compensation, early capacitor centralized compensation and microcomputer intelligent centralized compensation.
Capacitor single lamp compensation technology. It installs capacitors in single-lamp luminaires, disperses compensation, and achieves the purpose of improving power factor. It has better compensation effect for street lighting facilities of one road or even several roads. However, for different power supply stations, due to different types of lamps, such as roads, streets, lanes, and residential areas, the types of light sources are different, especially in most stations, where different wattages are installed, so the power factor of the entire station power supply system cannot reach the index. Claim. In addition, the open circuit damage of the capacitor is not easy to detect and difficult to maintain. Long-term operation will inevitably increase the reactive power loss of the entire power supply station, reduce the power supply efficiency, and waste power. This is a common situation in the field of road lighting.
Early capacitor centralized compensation technology. Its characteristic is that the mechanical contactor is used to control the switching mode of the capacitor, which has the characteristics of centralized compensation and automatic regulation of reactive power. The shortcoming is that the electric shock current is large, the inrush current is generated, the contact is easily burned, the service life of the contactor and the capacitor is shortened, and the switching time is long, which is easy to cause the compensation lag, and is not suitable for the three-phase unbalanced load. This technology is a standard in the early 1990s and is a phase-out technology that has rarely been adopted.
Microcomputer intelligent centralized compensation technology. Using single or DSP chip and large-scale centralized circuit as control module and data acquisition module, it can automatically track the reactive power change of the grid, quickly sample, calculate and send the switching signal. The switch module uses a high-power thyristor to achieve zero voltage input and zero current cut-off of the capacitor bank, no surge current surge, no spark and harmonic interference. This technology has been widely used as a new generation of centralized compensation technology.
Its main technical features: 1. Realize the digitization and intelligence of the control module to ensure the reliability of the control precision operation; 2. Fully automatic phase separation, segmentation automatic on-demand compensation; 3. Physical quantity sampling can be reactive current phase angle difference Such as the comprehensive amount, improve the grid power factor, reduce the total current, so that the load power factor is controlled at 0.95-0.99; 4. According to the specific conditions of the three-phase reactive power, select a single item to compensate separately, no inrush current Impact; 5. Using non-electrical switch, fast cutting speed, long service life; 6. Flexible setting of overvoltage, undervoltage, undercurrent delay and other parameters, with perfect over-limit alarm and over-voltage, owed Pressure, phase loss, lack of zero, harmonics, over-limit protection and shrinkage function to ensure safe operation of the system; 7. Adopt "self-healing" capacitors, with long service life, high reliability, small temperature rise, no special heat sink Advantages; 8. With data acquisition function and standard communication interface, it can realize remote real-time detection and computer network management. In addition, the centralized compensation technology, the original single lamp compensation device does not affect the street lamp system, but can better play the combination of centralized compensation and dispersion compensation, with good compensation and energy saving effect.
In short, both active energy-saving technology and reactive energy-saving technology have their own advantages, and should be comprehensively analyzed and selected according to the status of the power supply network and street lighting facilities. The author believes that: active energy-saving technology should adopt microcomputer control technology, reactive energy-saving technology should use capacitor single-lamp compensation technology.
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