并联电容器的谐波放大及对策

Harmonic amplification of capacitors in parallel and countermeasures

并联电容器是目前电网中普遍应用的无功补偿装置,用于提高功率因数,改善电能质量。由于电容器的阻抗呈容性,易与电力系统中的谐波产生相互影响,发生谐波的并联谐振和电容器对谐波电流的谐波放大,造成电容器和电气设备的损坏。通过实例分析了谐波对电容器的危害及并联电容器对谐波放大作用,应合理地配置电容器和电抗器,以避免电气参数匹配发生谐振,控制谐波电流放大。

Capacitors in parallel are reactive compensators commonly used at present in power supply network to increase power factors to improve quality of electric energy.As the impedance of a capacitor has its tolerance,it is easy to interact with the harmonics in the power supply system and results in parallel vibration of harmonics and the harmonic amplification of harmonic current by capacitor causing damage to capacitors and electric equipment.The detrimental effect of harmonics to capacitors and the amplifying effect of parallel capacitors on harmonics are analysed with typical examples.Capacitors and reactors should be matched on a rational basis so that harmonic vibration will not occur for mismatched electric parameters and amplification of harmonic current will be put under control.