鹤矿热电厂电网发生谐振的原因及预防

Cause and prevention of resonances occurred in electric power network of thermal power plant

铁磁谐振是中性点非有效接地系统经常发生的一种不正常运行现象,如果不加以治理任其发展,可能引发熔断器熔断、电压互感器烧毁、绝缘击穿、母线闪络等严重后果。文章就鹤岗矿业集团热电厂35kV供电系统的一次铁磁谐振,结合热电厂35kV供电系统结构、运行方式、事故处理程序以及谐振期间发生的现象,通过理论分析找出了发生此次铁磁谐振的原因,并提出了改进措施和运行管理的注意事项。

The 1/2 frequency division resonance is excited by the lightning short circuit impact and turbulence in the 35 kV power line and could make a unbalance of the three phrase voltages, when one or two phrase voltages rising in instant. Then the PT will be saturated and the PT excitation induction will be rapidly reduced. The waves of the voltage and current ware distortion and occurred overtone components. The overtone components could make the intrinsic 1/2 resonance frequency of the system same as the 1/2 resonance frequency of the current. The 1/2 frequency division resonance occurred could make the zero voltage at neutral point rapidly rising.