基于零序电压故障分量相位特征的发电机定子单相接地故障选相

Phase selection based on fault component phase characteristics of zero-sequence voltage for generator stator single-phase grounding fault

分析了不同中性点接地方式下定子单相接地故障时的机端三相电压特征,指出基于相电压大小的传统选相算法在高阻接地故障时灵敏度低且可能出现误选相。为此提出了一种基于零序电压突变量ΔU0和A相电势EA相位特征的发电机定子单相接地故障选相新原理,计算角度arg(ΔU0/EA),根据该角度所在的相位区域判断故障相。理论分析和仿真验证表明:该方法适用于各种中性点接地方式,提高了选相算法的抗过渡电阻能力;且该方法无需增加额外设备,简单易行。

The three-phase voltage characteristics of generator terminal during the stator single-phase grounding fault are analyzed for different neutral grounding modes and it is pointed out that,the traditional phase-selection algorithm may function improperly due to its lowered sensitivity during a high-impedance grounding fault. A phase-selection principle based on the zero-sequence voltage sudden change,ΔU0,and the phase-A potential,EA,is proposed for the generator stator single-phase grounding fault,which calculates the angle,arg（ΔU0/ EA）,and judges the faulty phase according to the phase zone of this angle. Theoretical analysis and simulative verification show that,without any additional equipment,this method is simple,feasible and suitable for various neutral grounding modes,and has better performance against transition resistance.