基于几何关系求解的汽轮发电机定子接地故障定位方法

Stator grounding fault location method of turbo-generator based on geometric relationship algorithm

提出一种基于几何关系求解的汽轮发电机定子接地故障位置定位方法。根据大型汽轮发电机定子绕组内部基波电势分布特征,将其电势相量依次相连后近似等效为平面上的一段圆弧,对应圆心角记为β,同时将发生接地故障时的定子零序电压、机端绕组相电压映射至该平面上,建立故障位置至中性点的基波电势与定子零序电压、机端绕组相电压等相量间的几何关系,结合零序回路阻抗特征参数,计算中性点至故障位置所对应的故障角γ,γ与β的比值即为接地故障位置。通过仿真试验及现场故障案例对所提方法进行验证。验证结果表明,所提方法简单有效,不依赖注入式定子接地保护,能大幅提高定子接地故障诊断效率,缩短故障排查时间。

A method of turbo-generator stator grounding fault location based on geometric relationship algorithm is proposed.According to the fundamental wave potential distribution characteristics of large turbogenerator stator windings,the potential vectors being connected in sequence are approximately equivalent to a circular arc on the plane,and the corresponding central angle is defined asβ.Meanwhile,the zero-sequence voltage of stator and the winding phase voltage are mapped to the plane when the grounding fault occurs.The geometric relationship between the fundamental potential from the fault position to the neutral point and the phasors such as the stator zero-sequence voltage and the winding phase voltage is established.Combined with impedance characteristic parameters of zero-sequence circuit,the fault angleγof the neutral point to grounding fault winding bar is calculated,and the ratio of angleγto angleβis calculated,which is the grounding position.The proposed method is verified by the simulation test and the field grounding fault case.The verification results show that the proposed method is simple and effective,and do not depend on the injection stator grounding protection,which can greatly improve the diagnosis efficiency of generator stator grounding fault and shorten the troubleshooting time.