基于希尔伯特-黄变换的变压器铁心振动特性分析

Analysis of Transformer Core Vibration Characteristics Using Hilbert-Huang Transformation

变压器铁心振动与铁心紧固状况、绝缘层损伤程度密切相关。利用希尔伯特?黄变换对非平稳信号的敏感性,提出一种可有效提取故障特征的铁心振动在线监测方法。对铁心振动信号进行经验模态分解,自适应地获得本征模态函数,继而对每组本征模态函数进行希尔伯特变换,得到了表征铁心振动信号时频变化的三维希尔伯特能量谱及边界谱,揭示了正常运行和隐含故障的铁心振动特征,为变压器的早期故障诊断奠定了坚实的基础。

The vibration signal of transformer core is correlative with the conditions of core compression and insulation, and vibration monitor is an effective method for on-line monitoring the transformer delitescent faults. A new method of obtaining the energy distribution with time and frequency of transformer core vibration based on Hilbert-Huang transformation （HHT） is developed. Firstly, decomposing the vibration series into a finite and small number of intrinsic mode functions （IMF）. IMF is directly decomposed from vibration series and can reflect the intrinsic physical property of vibration series more clearly. Secondly, applying the Hilbert transform to each IMF. Then, achieving the three-dimensional （amplitude/energy-frequency-time） Hilbert spectrum and marginal spectrum, where both amplitude and frequency are functions of time. Eliminating the spurious harmonics without physical mean, the Hilbert spectrum and marginal spectrum provide high-resolution time-frequency characteristics, the test results show vibration characteristics of transformer core. It is demonstrated by actual analysis that the new detection method is one effective way for the condition evaluation and fault diagnosis of transformer core.