基于HHT的双馈异步发电机电刷滑环烧伤故障诊断

Diagnosis method based on HHT of burn fault of doubly-fed induction generator brush ring

在实际工程应用中,双馈异步发电机电刷滑环故障发生较为频繁,对电机励磁稳定性影响也较大,严重时还会导致发电机组的解列。因此提出一种基于HHT的双馈异步发电机电刷滑环烧伤故障诊断方法。首先通过PSCAD/EMTDC电力系统仿真软件模拟滑环烧伤故障,得到故障前后流经电刷滑环的励磁电流。然后基于希尔伯特-黄变换理论提取故障特征量,并将仿真结果与实测励磁电流信号所得Hilbert谱图进行对比分析,验证了故障特征量诊断法的可行性。最后提出能量商的诊断特征值概念,计算不同故障等级下特征量的能量商值,并与红外测温探头测量滑环表面的温度值进行对比。分析二者变化趋势,发现高于100 Hz的周期性高频分量不但可以作为故障特征量,而且其能量商在诊断滑环发生轻微烧伤故障时具有更高的精度和灵敏度。该方法为实际工程研究提供了一定的指导意义。

In practical engineering,the fault of brush slip ring of Doubly-Fed Induction Generator(DFIG)occurs frequently,and the excitation stability of the motor is also greatly affected,which will lead to the disconnection of the generator set.Therefore,this paper proposes a fault diagnosis method of burn of doubly-fed induction generator brush slip ring based on Hilbert Huang Transform(HHT).First it uses the PSCAD/EMTDC power system simulation software to simulate the slip ring burn fault and obtain excitation current through the brush and slip ring before and after fault.Then fault features are extracted based on HHT theory,and the simulation results and the Hilbert spectra gotten from the measured excitation current signal are compared and analyzed to verify the feasibility of fault feature diagnosis method.Finally,the concept of energy quotient diagnostic features is proposed,the energy quotient of features of different fault levels calculated and then compared with the slip ring surface temperature value measured by the infrared temperature measuring probe.Their variation trend is analyzed,finding that the periodic frequency the components which is higher than 100 Hz can be used as the fault feature,and its energy quotient has higher accuracy and sensitivity in diagnosing minor burn of slip ring.This method provides some guiding significance for practical engineering research.