谐波--------电力方向毕业设计英文文献翻译(附中文).doc

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谐波--------电力方向毕业设计英文文献翻译(附中文),service reliability and quality of power have become growing concerns for many facility managers, especially with the increasing sensitivity of electronic equip...
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Service reliability and quality of power have become growing concerns for many facility managers, especially with the increasing sensitivity of electronic equipment and automated controls. There are several types of voltage fluctuations that can cause problems, including surges and spikes, sags, harmonic distortion, and momentary disruptions. Harmonics can cause sensitive equipment to malfunction and other problems, including overheating of transformers and wiring, nuisance breaker trips, and reduced power factor.
What Are Harmonics?
Harmonics are voltage and current frequencies riding on top of the normal sinusoidal voltage and current waveforms. Usually these harmonic frequencies are in multiples of the fundamental frequency, which is 60 hertz (Hz) in the US and Canada. The most common source of harmonic distortion is electronic equipment using switch-mode power supplies, such as computers, adjustable-speed drives, and high-efficiency electronic light ballasts.
服务的可靠性和电能质量已成为越来越多设施经理的关注,尤其是随着电子设备和自动化控制灵敏度提高了很多。有几种类型的电压波动可能导致问题,包括浪涌和尖峰,凹陷,谐波失真,一时中断。谐波可能导致敏感的设备出现故障和其他问题,包括变压器、线路和断路器过热传输滋扰,并降低功率因数。
什么是谐波?
谐波电压和电流的频率在正常正弦电压和电流波形时为最佳。通常,这些谐波频率是基本频率,这里是60赫兹,在美国和加拿大(赫兹)的倍数。谐波失真的最常见的来源是使用电子设备开关电源,如电脑,调速器,以及高效率的电子灯用镇流器。
谐波也造成了这些“开关负载”(也称为“非线性负载”,因为目前不随电压变化,因为它是简单的电阻和负荷的反应):每次电流接通和关断时间使电流脉冲产生。由此产生的脉冲波形组成的谐波频率频谱,包括60赫兹和它的倍数。从这个电压畸变到失真,结果目前通常反应在系统阻抗。(阻抗是完全对立的措施—电阻,电容和电感—交变电流。)在更高频率的波形,统称为总谐波失真(THD),不执行任何有用的工作,也可以成为重要的滋扰。
谐波波形的特点是其振幅和谐波级次。在美国和加拿大,三次谐波为180赫兹或3 × 60赫兹和第五次谐波为300赫兹(5 × 60赫兹)。第三谐波(和它的倍数)是在单相负载电