铁磁谐振对电压互感器的危害及采取的措施 The damage of ferromagnetic resonance to voltage transformer and the measures taken 铁磁谐振产生的过电流和/或高电压可能造成电压互感器损坏,特别是低频谐振时,电压互感器相应的励磁阻抗大为降低而导致铁芯深度饱和,励磁电流急剧增大,高达额定值的数十倍至百倍以上,从而严重损坏电压互感器。损坏电压互感器通常有两种情况: Ferromagnetic resonance produced by over current and/or high voltage may cause damage of voltage transformer, especially low frequency resonance, the corresponding excitation voltage transformer impedance caused greatly reduced depth of iron core saturation, field current increases sharply, as high as dozens of times to one hundred times bigger than the rating, which seriously damage voltage transformer. There are usually two cases of damaged voltage transformers: ①电压互感器的一次绕组烧坏,这是持续的铁磁谐振造成的。一般是发生在空载母线合闸时,该相母线的对地电容较小,产生三倍频的高频谐振过电压。 One winding of a voltage transformer is burnt out, which is caused by continuous ferromagnetic resonance. In general, the capacitance of the phase bus is small in the case of the no-load bus, which produces a high frequency resonance overvoltage of three times frequency. ②高压熔断器频繁熔断。是由超低频铁磁谐振造成。超低频铁磁谐振是在单相接地故障消失瞬间,电网对地电容与电压互感器励磁电感产生的一种短暂电磁振荡。这种情况出现在空载母线合闸时有较大的母线对地电容的电网中。尤其是在间隙性电弧接地故障时,更为严重。 利用电压互感器限制或消除铁磁谐振的措施及其分析消除铁磁谐振的方法有很多种,下面将分别介绍对电压互感器二次和一次采取措施,来限制或消除谐振过电压。 The high voltage fuse fuses frequently. It is caused by low frequency ferromagnetic resonance. Ultra-low frequency ferromagnetic resonance is a transient electromagnetic oscillation caused by the excitation inductance of the grid capacitance and voltage transformer. This situation occurs when there are large busbar capacitors in the grid of capacitance. Especially in the intermittent arc grounding fault, more serious. Using voltage transformer to limit or eliminate ferroresonance measures and analysis of the method of eliminating ferroresonance has a lot of kinds, the following will introduce respectively of voltage transformer secondary and take measures, to limit or eliminate resonant overvoltage.