摘要
随着非线性负荷的逐年增加,电网中的谐波污染越来越严重,给无功补偿电容器的正常运行带来了许多不利的影响。电容器会对谐波电流产生放大作用,进一步导致电容器谐波过载,缩短使用寿命。更为严重的是,无功补偿电容器组与系统参数共同作用还可能会造成谐振,使电容器出现严重的过电流和过电压,危害设备的安全。
近年来,东莞电网中的并联补偿电容器出现了不同程度的损坏问题,是否由电网中的谐波所造成,谐波对电容器有何影响,这是本文的主要研究内容。为了研究这一问题,对东莞电网中13个变电站中的并联补偿电容器组进行了谐波监测,得到电容器的谐波数据。本文利用电容器与谐波的相互影响的理论,以及电容器的过载能力理论,对监测数据进行了分析:一方面,分析了电容器对谐波电流的放大作用。利用简化的模型,并就电路参数的影响,串联和并联谐振等情况进行了分析;另一方面,就电网谐波对电容器危害进行了理论分析,电容器都有一定的谐波过载能力,但谐波较为严重时可能会造成电容器过电流和过电压,增加其热效应,使电容器损坏,寿命缩短。
With the non-linear load increasing year after year,the harmonics pollution of the power system is increasingly serious.It brought the disadvantageous influence on the reactive compensation capacitor.It causes the harmonics current to enlarge,harmonic over-load,a short time use and damange indeed.The more serious is that the common function of capacitor and the system parameters will cause resonance,which will make capacitor appear over current and over voltage and endanger the safety of the electrictity equipments and power system operation.
In recent years,the reactive compensation capacitors in power grid of Dongguan,suffered different degrees of damage.Was it caused by the harmonics?What is the harm of harmonics on the capacitor?This is the contents of the article. The capacitors in more than 10 substations of Dongguan grid were monitored in order to get the harmnonics data. Using the theory of interaction between the capacitors and harmonics, and the theory about capacitors over-load.This article analyzed the monitoring data to get a conclusion.On the one hand,the capacitors cause the harmonics current to enlarge.To a simplified model, it is analyzed, such as serial and parallel resonance, the influence of circuit parameters. On the other hand,the harmonics have harm to the capacitors. Capacitors have a certain harmonic overload, but the harmonics may cause more serious over-current and over-voltagecapacitors to increase its thermal effect,then the capacitor is damaged,shortened life expectancy.
引文
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