对电压互感器饱和引起电位偏移与铁磁谐振的分析

Voltage shift and ferroresonance caused by voltage transformer saturation

分析了串联铁磁谐振电路的2种稳定工作状态,即非谐振状态和谐振状态。前者电路呈电感性,回路电流和电感、电容上电压都不大;后者电路呈电容性,不仅回路电流大,且电感、电容上产生过电压。利用等值电路变换及矢量分析的方法,对配电网络中电磁式电压互感器饱和引起的过电压现象进行了分析。结果表明:在中性点绝缘系统中,电磁式电压互感器饱和会使系统中出现不同程度的中性点电位偏移,导致一相或两相对地电压升高,但系统中并未发生真正的工频铁磁谐振。故可得出结论:在中性点绝缘系统中,因电磁式电压互感器饱和引起的过电压现象属于工频位移过电压。

Two kinds of stable conditions of series ferromagnetic resonance circuit are analyzed：non -resonance and resonance conditions. Under the former condition,the circuit is inductive,with the loop current as well as voltages on the inductance and the capacitance being small. Under the latter condition,the circuit is capacitive,with large loop current and over-voltages on the inductance and the capacitance. By means of the equivalent circuit conversion and the phase graph analysis,the over-voltage caused by the electromagnetic voltage transformer saturation in distribution networks is studied. Results show that,in the system with insulated neutral,the electromagnetic voltage transformer saturation will raise voltage shift of various degrees at the neutral point and lead to line- to- earth voltage increase on one or two phases,but the real voltage ferroresonance does not happen in these situations. Therefore,the over-voltage caused by the electromagnetic voltage transformer saturation in the system with insulated neutral belongs to shifting over-voltage.