基于定子绕组并联支路环流特性的发电机故障识别方法

Generator Fault Diagnosis Based on the Circulating Current in Stator Winding Parallel Branches

分析了发电机气隙磁势、磁导、磁密、定子绕组两条并联支路的感应电势和电路方程,得到定 子绕组并联支路间的电压差表达式。通过分析正常及故障运行时各参数的变化得到了并联支路电 压差和环流特性,理想电机在正常运行时不存在电压差和环流,而转子绕组短路故障将引起二次谐 波环流,定子绕组短路、定转子气隙静偏心、气隙动偏心故障将引起基波环流。由于不同故障引起 的环流特性存在差别,提出了基于定子绕组并联支路环流特性的发电机故障识别方法,并实测了 SDF-9型故障模拟发电机正常及故障运行时的环流信号,与理论分析结果基本吻合。

Generator parameters are firstly analyzed, viz the air-gap magnetomotive force, the magnetic permeability, the magnetic flux density, the stator winding parallel branches electromotive force distribution to derive a formula giving the difference of electromotive force among stator winding parallel branches. Secondly, through analyzing the parameters changing under normal operation condition and fault condition, the circulating current characteristics are investigated based on the proposed formula. The investigation reveals that the generator does not have the circulating current when operating normally and the second harmonics circulating current increases when the rotor winding inter-turn short circuit fault occurs, and the fundamental circulating current increases when the stator winding inter-turn short circuit or air-gap eccentric fault occurs. Considering the difference of the circulating currents caused from different faults, a method of generator fault diagnosis based on the circulating current is proposed. Finally, the circulating current of a type SDF-9 generator is measured in laboratory to verify the theoretical analysis presented above.