摘要
根据局部放电信号的特征,提出了强噪声背景下基于分数阶傅立叶变换(FRFT)的数据预处理和小波平滑去噪的局部放电信号提取方法。含噪信号经过FRFT后,在FRFT域内,随着阶次p的变化,信号能量谱呈现不同的时频聚集性,利用最小均方误差(MM SE)准则扫描到最优阶的FRFT域,根据3σ法则采用硬阈值法进行数据预处理。为进一步提高局部放电信号的提取精度,采用db8小波及无偏似然估计阈值规则进行平滑去噪。通过对仿真信号和实测信号的分析,验证了本文方法的有效性与可行性。
This paper proposes a partial discharge （PD）signals analysis method based on Fractional Fourier Transform and Wavelet Transform under strong noises background. In Fractional Fourier domain, the energy spectrums time-frequency congregation of the noise include signals varies with the change of order p. The optimal order of FRFT is derived according to the minimum mean square error （MMSE） criterion. Hard threshold method according to 3σ rule is introduced for PD data pretreatment. Db8 wavelet and the soft threshold based on Stein＇s Unbiased Estimate of Risk are used to smoothly denoise for better PD signals extraction. The simulation and experimental results validates the effectiveness and feasibility of the proposed method.
出处
《吉林电力》
2008年第3期4-8,共5页
Jilin Electric Power
关键词
局部放电
分数阶傅立叶变换
3σ法则
小波变换
partial discharge
Fractional Fourier Transform
3σ rule
Wavelet Transform
