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Low power consumption of the harmonic source


Abstract: The low-voltage distribution network of non-linear life, the harmonic characteristics of electrical equipment were introduced and analyzed, with the power electronics technology and human living standards, the number and proportion of harmonic sources in the network will rapidly increase, the purpose of this paper is to help people enhance their everyday electrical equipment in the harmonic understanding to facilitate the harmonic suppression and control technology research and in-depth.
Keywords: low voltage distribution network harmonic characteristics of electrical equipment nonlinear
Low-voltage power supply from the power various electrical equipment, and enterprises in the municipal life was widely used in such appliances, many home appliances with non-linear components, will produce harmonic currents, mainly TV, all kinds of energy saving lamps, refrigerators, washing machines, microwave oven, induction cooker, computer, laser printer, battery charger, various medical and scientific equipment and facilities, timing drive � such as air conditioning compressor, high-rise buildings use � such a large elevator, which mostly use the thyristor, a low-power rectifier devices, power electronics,[link widoczny dla zalogowanych], electrical appliances, some with small-capacity transformers. The excitation current, the proportions of individual capacity even though the hundreds of watts to several small � kilowatts �, but the large number and wide distribution, they will be produced by high harmonic impact on power system, increase the power network harmonic pollution. 1. TV appliances greatest impact on electrical harmonic is the TV group. As a result of single-phase bridge rectifier capacitor smoothing circuit,[link widoczny dla zalogowanych], the rectifier device to wait until the rectifier voltage is greater than the energy storage capacitor voltage to turn. AC current so that only the first part of the sine wave. The characteristics of all the odd harmonic harmonic and fundamental harmonic of the peak and coincide with peaks. The same power of multi-phase voltage harmonics produced TV the same phase, but at the same time the usage rate, resulting in the increase of harmonic distribution network. Color television sets than the peak current large black and white TV, especially 3, 5, 7 and 9 is particularly serious. 2. Linear lighting power the most widely used lighting is incandescent,[link widoczny dla zalogowanych], but it is low efficiency,[link widoczny dla zalogowanych], large power consumption. Emerged in recent years a variety of energy-saving lamps, much higher efficiency than incandescent. But the incandescent lamp is a linear load, and energy-saving lamps are almost all harmonic sources, in the evening, that is, the peak time allocated to write, but mostly energy-saving lamps for harmonic current distortion rate is lower than the TV, different kinds and types of energy-saving lamps Main harmonic currents phase has also been distributed. The main energy-saving lamps are fluorescent lamps, high pressure gas discharge lamps and dimming incandescent lamps and so on. 2.1 all fluorescent lamps contain harmonic current rates vary greatly. Before using a common long-tube fluorescent lamps, is now more and more compact lights, which there are various subtypes,[link widoczny dla zalogowanych], their harmonics have the following characteristics: 1, features all the odd harmonic currents harmonics. Wound ballast current rate of three times with the higher harmonics, up to 8 ~ 10%. Electronic ballast type pulse rate of each homogeneous with 15 to 18%, and 3 times for 70 ~ 80%, the higher the number, with lower rates; high frequency harmonics with the low rate, generally 3 ~ 15 %. 2, used in wound compact lamp ballast capacitor in parallel with the third subtype, in order to improve the power factor, reduce current and line losses, but the capacitor from the obvious role of harmonic amplification. 3, a second subtype of electronic ballasts subject to a further rectifier inverter, to produce 20 ~ 60HZ Power supply tube fed through high-frequency transformer, so in addition to 3 to 19, outside the homogeneous harmonic current , there are high frequency harmonic current content. 2.2 high pressure gas discharge lamp using high-pressure gas discharge lamps have a certain pressure mercury, sodium, dysprosium, indium and metal halide vapor discharge negative resistance characteristics, it cascaded nonlinear ballast devices, high pressure sodium and mercury lamp used more. High-pressure gas discharge lamp is mainly used for streets, squares, open pit, etc. The lighting, the harmonic characteristics are the main produce 3,5,7 harmonics, its volume increases with the increasing capacity of the lamp. 2.3 dimming incandescent dimming incandescent or other appliances through the power conditioning circuit is removed with the silicon part of sinusoidal current to regulate the size of the load current. Characterized by harmonic currents all the odd harmonics, different control angle α of the harmonic current content in different, generally, α greater, the greater the harmonic current content. 3. 3.1 air conditioning appliances with economic development and people's living standards, Air conditioning electricity soared year after year. As the air conditioning power is larger � 600W each to several kilowatts �, so in many cities, municipal electric air conditioning load will rise to the top. Therefore, air-conditioning electricity consumption in the nature of linear or nonlinear, and the future city network background harmonic gain is closely related to the relevant tests show that the harmonic current size of the air conditioner according to work and change, and only fan, THDi % 6 9%, cooling time is 20 ~ 27%, heating time is 22 ~ 34%, harmonic distribution of 2 to 17 times, can be seen, whether cooling or heating, THDi not small, but single of the harmonic currents much larger than the TV. Moreover, the continuous improvement process air conditioners, inverter air-conditioning applications has become increasingly widespread, Frequency Converter and more harmonic content and distribution, and therefore the harmonic management in terms of distribution network to address various types of air conditioning capacity to investigate the harmonic and development of related standards. 3.2 household refrigerators refrigerator and color TV power similar to the harmonic currents with much smaller rate than TV, but the participation of the night refrigerator appliances harmonic harmonic peaks. Its harmonics are mainly 3, 5 and 7, which contains 3 times the rate of 10 ~ 13%, 5 times for 3 to 5%, 7 0.5 ~ 2%, 7 times or more less than 0.8%. 3.3 washing machine washing machine and refrigerator close to power, harmonic current distortion rate slightly. However, the short boot time every day to participate in the night, while the peak harmonic coefficient of household appliances is not. , For example, washing machines produced by the 3rd harmonic content ratio from 21 to 40%, 5 4.5 ~ 9%, 7 3 ~ 6%, 9 1 ~ 4%, 13 times more than small.
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