基于小波包能量熵的油纸绝缘气隙放电阶段识别

Stage Identification in Air-gap Discharge of Oil-impregnated Paper Insulation Based on Wavelet Packet Energy Entropy

油纸绝缘气隙放电是运行变压器局部放电的主要方式,研究其发展阶段对变压器潜伏性故障的有效监测及诊断具有重要意义。论文模拟实际变压器运行环境建立油纸绝缘气隙放电缺陷模型,利用恒压法采集其局部放电信号,采用小波包分解对局放信号进行频带划分,获取其各频带下信号能量分布以及局放发展过程信号总能量发展情况,基于不同频带下信号能量变化特征提出以小波包能量熵作为局部放电发展特性的新特征量,通过小波包能量熵在整个过程中的循环变化特征规律,提出以小波包能量熵"阶跃"断层点为支点的局部放电阶段有效划分方式,并根据小波包能量熵在不同阶段的阈值特点,建立通过阈值判定来识别局部放电发展阶段的模型。

Air-gap discharge is the main type of partial discharge（PD） within power transformer. It is of great significance to study the discharge development stage for the monitoring and diagnosis of transformer potential faults. This paper build an air-gap discharge model in simulative transformer tank, collecting PD signals based on constant voltage method, utilizing wavelet packet decomposition method to partition the PD signal bands obtaining signal energy distribution in each frequency band as well as total signal energy tendency along with PD development process. The new PD parameter describing the development process, wavelet packet energy entropy, was proposed based on the signal energy variation in each frequency band. Due to the cyclic change of wavelet packet energy entropy, the step points of wavelet packet entropy are taken as the way to effectively divide the PD development stage. According to the thresholds of wavelet packet energy entropy in different stages, the PD development stages were identified.