水轮发电机中性点接地装置选型分析

水轮发电机中性点接地装置选型需要考虑定子接地故障电流、故障点暂态过电压和位移电压等。针对某水电站中性点装置的两种接地装置,定量分析对比参数调节对接地点故障电流、故障电流中阻性与容性成分的比值以及中性点位移电压放大系数等关键参数的影响。通过对比得出:案例中高阻抗变压器方案仅能在中性点位移电压较小时,以放大位移电压为代价来降低接地故障电流,调节效果是单向的;而并联电抗方案的参数调节是双向的,相比高阻抗变压器方案其现场调节的灵活性更好。

Analysis on Type Selection of Hydro-generator Neutral Grounding Device

In order to control the grounding current,transient overvoltage and displacement voltage,the neutral grounding device is needed in hydropower station.The fault current in grounding point,the reactance and impedance proportion in fault current,the amplification factor of displacement voltage of neutral point between grounding devices with high impedance and shunt reactance in a hydropower station are compared.The calculations are as follows:in this case,the high impedance scheme can reduce the fault current at the low displacement voltage,but it increases the displacement voltage too,and the adjustment is unidirectional,while the adjustment of shunt reactance scheme is bidirectional,which has better flexibility in the site adjustment.