基于能量比预处理的FFT窄带滤波方法  

FFT narrowband filtering method based on energy-ratio pretreatment

作　　者：卢毅[1] 韩志锟[1] 陈瑜[1] 

机构地区：[1]东南大学电气工程学院,南京210096

出　　处：《东南大学学报（自然科学版）》2010年第5期948-951,共4页Journal of Southeast University：Natural Science Edition

摘　　要：分析了有效信号和窄带干扰在频域上的缓变和突变的特点,提出了一种基于能量比预处理的改进FFT窄带滤波方法.利用功率谱信号一个时间窗内的前后能量对比将原低于有效信号的窄带干扰进行放大,为FFT窄带滤波的阈值的确定打下基础.对于超过阈值的窄带干扰信号,在频域处理时采用对有效信号保持原数值、干扰信号进行压缩的处理方法,防止了由于滤波而造成的信号的畸变,达到了保留信号特征的目的.处理结果表明,时间窗取8~10个记录点,阈值系数取0.3~0.4,任何原始信号的信噪比都能取得较好的滤波效果.Slow and abrupt changing characteristics of PD（partial discharge） signals and narrowband interference in frequency domain are analyzed,and an improved FFT（fast Fourier transform） filtering method based on energy-ratio pretreatment is proposed.By using energy-ratio of pre and post power spectrum signals in one time window,narrowband interference signals which are lower than PD signal are amplified,so as to determine the threshold of FFT narrowband filtering.For narrowband interference signals above the threshold,PD signals are maintained while interference signals are compressed,so as to prevent the distortion of signals due to filtering and retain the signal characteristics.Results show that by taking 8 to 10 points in the time window and 0.3 to 0.4 as threshold value,the method can get a better filtering effect regardless of SNR（signal to noise ratio） of the original signals.

关 键 词：局部放电 能量比法 窄带干扰 滤波 

分 类 号：TM855[电气工程—高电压与绝缘技术]