基于能量比预处理的FFT窄带滤波方法
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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.
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.
引文
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[11]毛汉领,陈仲仪,庄红宇.能量比时间延迟估计法及在定位中的应用[J].广西工学院学报,1994,5(2):12-16.Mao Hanling,Chen Zhongyi,Zhuang Hongyu.The timedelay estimation based on the energy ratio and its applica-tion on the localization[J].Journal of Guangxi Instituteof Technology,1994,5(2):12-16.(in Chinese)
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[13]卢毅,杨静.GIS在线检测中局部放电和外部干扰信号的识别[J].电力系统自动化设备,2007,27(6):71-73.Lu Yi,Yang Jing.Distinguish between partial dis-charge and external interference signal for GIS on-linemonitoring[J].Electric Power Automation Equip-ment,2007,27(6):71-73.(in Chinese)
[14]姜玉磊,卢毅,田新启.GIS局部放电在线检测系统开发[J].江苏电机工程,2005,24(2):16-17.Jiang Yulei,Lu Yi,Tian Xinqi.Research on on-linemonitoring system of partial discharge for gas insulatedswitchgear[J].Jiangsu Electrical Engineering,2005,24(2):16-17.(in Chinese)
[2]Christophorou L G,Olthoff J K,van Brunt R J.Sulfurhexafluoride and the electric power industry[J].IEEEElectrical Insulation Magazine,1997,13(5):20-24.
[3]Kawada Masatake,Tungkanawanich Ampol,KawasakiZen-Ichiro.Detection of wide-band E-M signals emittedfrom partial discharge occurring in GIS using wavelettransform[J].IEEE Transactions on Power Delivery,2000,15(2):467-471.
[4]Hoshino Toshihiro,Kato Katsumi,Hayakawa Naoki.Frequency characteristics of electromagnetic wave radia-ted from GIS apertures[J].IEEE Transactions on Pow-er Delivery,2001,16(4):552-557.
[5]Hikita M,Yamashita H,Hoshino T,et al.Electromag-netic noise spectrum caused by partial discharge in air athigh voltage substations[J].IEEE Transactions onPower Delivery,1998,13(2):434-439.
[6]唐炬,朱伟,孙才新,等.GIS局部放电的超高频检测[J].高电压技术,2003,29(12):32-34.Tang Ju,Zhu Wei,Sun Caixin,et al.Analysis of UHFmethod used in partial discharge detection in GIS[J].High Voltage Engineering,2003,29(12):32-34.(inChinese)
[7]桂俊峰,高文胜,吴振声,等.能量比值法定位变压器局部放电[J].高电压技术,2006,32(1):38-40.Gui Junfeng,Gao Wensheng,Wu Zhensheng,et al.Location of partial discharge in transformer by energyratio method[J].High Voltage Engineering,2006,32(1):38-40.(in Chinese)
[8]王晓宁,朱德恒,李福祺,等.现场局部放电信号中周期性窄带干扰的抑制[J].高电压技术,2003,29(4):16-18.Wang Xiaoning,Zhu Deheng,Li Fuqi,et al.Rejectionfor periodical narrow-band noises of on-site PD monito-ring signals[J].High Voltage Engineering,2003,29(4):16-18.(in Chinese)
[9]白建社,陈丹,王成多,等.基于移动FFT的PD在线检测中正弦干扰抑制方法[J].电力系统及其自动化学报,2007,19(6):118-123.Bai Jianshe,Chen Dan,Wang Chengduo,et al.Mov-ing FFT based approach for rejecting sine interference inon-line PD measurements[J].Proceedings of the CSU-EPSA,2007,19(6):118-123.(in Chinese)
[10]谢良聘,朱德恒.FFT频域分析算法抑制窄带干扰的研究[J].高电压技术,2000,26(4):6-8.Xie Liangpin,Zhu Deheng.Research of spectrumanalysis based on FFT for suppressing narrow-band in-terference in PD signal[J].High Voltage Engineering,2000,26(4):6-8.(in Chinese)
[11]毛汉领,陈仲仪,庄红宇.能量比时间延迟估计法及在定位中的应用[J].广西工学院学报,1994,5(2):12-16.Mao Hanling,Chen Zhongyi,Zhuang Hongyu.The timedelay estimation based on the energy ratio and its applica-tion on the localization[J].Journal of Guangxi Instituteof Technology,1994,5(2):12-16.(in Chinese)
[12]左国平,王彦春,隋荣亮.利用能量比法拾取地震初至的一种改进方法[J].石油物探,2004,43(4):35-37.Zuo Guoping,Wang Yanchun,Sui Rongliang.An im-proved method for first arrival pickup using energy rati-o[J].Geophysical Prospecting for Petroleum,2004,43(4):35-37.(in Chinese)
[13]卢毅,杨静.GIS在线检测中局部放电和外部干扰信号的识别[J].电力系统自动化设备,2007,27(6):71-73.Lu Yi,Yang Jing.Distinguish between partial dis-charge and external interference signal for GIS on-linemonitoring[J].Electric Power Automation Equip-ment,2007,27(6):71-73.(in Chinese)
[14]姜玉磊,卢毅,田新启.GIS局部放电在线检测系统开发[J].江苏电机工程,2005,24(2):16-17.Jiang Yulei,Lu Yi,Tian Xinqi.Research on on-linemonitoring system of partial discharge for gas insulatedswitchgear[J].Jiangsu Electrical Engineering,2005,24(2):16-17.(in Chinese)
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