【摘要】 为准确分析计算定子绕组接地间歇弧光过电压以及故障电流,分析发电机中性点消弧线圈接地的规律,文中采用准分布电容参数的多回路模型对三峡1台700 MW的大型水轮发电机进行计算。该模型将定子绕组划分成多个单元电路,计及气隙磁场谐波以及定子绕组分布电容的影响。结果表明,发电机中性点采用消弧线圈接地方式下,定子单相接地时,适当增加阻尼率可以有效地抑制电压熄弧恢复过程中的超调量,从而限制重燃暂态过电压;选择较小的脱谐度可以有效地补偿电容电流的基波分量,可大大减小故障电流,但故障电流中的3次谐波难以削弱。另外,频率偏移可引起较大的暂态过电压。更多还原

【Abstract】 In order to calculate the transient overvoltage and fault current accurately during the stator intermittent arc grounding, and to analyze the behavior of generator with Peterson coil neutral grounding, this paper presents a multi-loop mode] with quasi-distributed capacitances. The proposed model can better describe the influences of the distributed capacitance and the harmonic magnetic field in air gap. Based on the model, this paper studies a 700 MW hydrogenerator with neutral resonant grounding in Three Gorges, China. Simulation results indicate that increasing the damping ratio properly can suppress the overshoots of the recovery voltage when arc is extinct, so that the transient overvoltage during re-strike is restrained. Furthermore, selecting small degree of tuning can effectively compensate the fundamental capacitance current, and hence reduce the fault current. The disadvantage is the difficulty to reduce the triple-harmonic component in the fault current and the greater transient overvoltage which may be caused by the frequency deviation.更多还原