基于小波分析的间谐波检测与去噪研究
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摘要
随着非线性负载的大量使用,电网中的谐波问题越来越复杂。间谐波作为一种特殊的谐波,其频率是基波频率的非整数倍。间谐波的大量存在会使电能质量恶化,引发闪变,引起继电器误操作等。目前间谐波问题已经引起了人们的广泛关注,对其进行精确检测和分析具有十分重要的意义。
论文以间谐波为研究对象,简述了其主要来源和危害,分析了经典的傅里叶变换方法用于间谐波检测的不足,选择了小波分析方法研究间谐波问题。小波变换是傅里叶变换的继承和发展,具有良好时频局部化特征及多分辨率特性,在间谐波检测中获得了广泛应用。
论文针对间谐波信号含高斯白噪声情形研究了信号去噪问题,提出新阈值函数用于信号降噪;因小波基函数的不理想紧支性,连续小波变换方法用于间谐波检测存在一定的局限。小波包具有更为精细的频带划分特性,可将信号分解至不同子频带。结合连续小波变换和小波包的优点,本文采用了改进的小波变换方法检测间谐波参数。
仿真结果表明,基于小波分析方法进行间谐波检测和分析是行之有效的,完成了信号降噪和频率等参数的精确检测,为间谐波测量提供了一种有效的解决方案。
With the widely using of non-linear loads,the problems of harmonics have become more complicated in power system.Interharmonic is a special kind of harmonic which is non-integer of the fundamental frequency.A mass of the interharmonics that existed may make the power quality worse,resulting in flicker and the wrong running of relay.Recently,the harms of interharmonics have been attracted extensive attention.It's important to detect and analyze them accurately.
The paper described the main resources and harms of interharmonics.The shortcomings of Fourier Transform adopted in their detections was analysed and the Wavelet method was selected for interharmonics.The Wavelet Transform was inherited and developed from the Fourier Transform,it has good time-frequency features and mutli-resolutions,and has been widely used in the measurement of interharmonics.
For the case of the interharmonics with Guass white-noise,a new improved wavelet threshold function was proposed for signal denoising;For the non-ideal compactly supported property of the wavelet function,the continuous wavelet transform(CWT) which is used in the detections has some limitations,while the wavelet packet transform(WPT) has more detail partitions which could split the frequency into the non-zero band.Combined with the merits of both methods,an improved method was adopted to measure the parameters of interharmonics.
The results simulated by Matlab reveals that the measurements and the analysis of interharmonics based on wavelet method are valid.Wavelet analysis can be used for signal-denoising and detect frequency accurately,therefore it has supplied an effective solution for the measurement of interharmonics.
论文以间谐波为研究对象,简述了其主要来源和危害,分析了经典的傅里叶变换方法用于间谐波检测的不足,选择了小波分析方法研究间谐波问题。小波变换是傅里叶变换的继承和发展,具有良好时频局部化特征及多分辨率特性,在间谐波检测中获得了广泛应用。
论文针对间谐波信号含高斯白噪声情形研究了信号去噪问题,提出新阈值函数用于信号降噪;因小波基函数的不理想紧支性,连续小波变换方法用于间谐波检测存在一定的局限。小波包具有更为精细的频带划分特性,可将信号分解至不同子频带。结合连续小波变换和小波包的优点,本文采用了改进的小波变换方法检测间谐波参数。
仿真结果表明,基于小波分析方法进行间谐波检测和分析是行之有效的,完成了信号降噪和频率等参数的精确检测,为间谐波测量提供了一种有效的解决方案。
With the widely using of non-linear loads,the problems of harmonics have become more complicated in power system.Interharmonic is a special kind of harmonic which is non-integer of the fundamental frequency.A mass of the interharmonics that existed may make the power quality worse,resulting in flicker and the wrong running of relay.Recently,the harms of interharmonics have been attracted extensive attention.It's important to detect and analyze them accurately.
The paper described the main resources and harms of interharmonics.The shortcomings of Fourier Transform adopted in their detections was analysed and the Wavelet method was selected for interharmonics.The Wavelet Transform was inherited and developed from the Fourier Transform,it has good time-frequency features and mutli-resolutions,and has been widely used in the measurement of interharmonics.
For the case of the interharmonics with Guass white-noise,a new improved wavelet threshold function was proposed for signal denoising;For the non-ideal compactly supported property of the wavelet function,the continuous wavelet transform(CWT) which is used in the detections has some limitations,while the wavelet packet transform(WPT) has more detail partitions which could split the frequency into the non-zero band.Combined with the merits of both methods,an improved method was adopted to measure the parameters of interharmonics.
The results simulated by Matlab reveals that the measurements and the analysis of interharmonics based on wavelet method are valid.Wavelet analysis can be used for signal-denoising and detect frequency accurately,therefore it has supplied an effective solution for the measurement of interharmonics.
引文
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[3]Gunther E W.Interharmonics in power system[C].IEEE Power Engineering Society Summer Meeting,2001
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[6]Hu L,Ran L.Direct method for calculation of AC side harmonics and interharmonics in an HVDC system[J].IEEE Proceedings on Generation Transmission and Distribution,2000,147(6):329-335
[7]Mattavelli P,Felin L,Bordignon P,Perna M.Analysis of interharmonics in DC arc furnace installations[C].Eighth International conference on Harmonics and Quality of Power,Athens,Greece,1998
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[9]Barros J,Perez E,Pigazo A,Diego R I.Simultaneous measurement of harmonics,interharmonics and flicker in a power system for power quality analysis[C].Fiflh International Conference on Power System Management and Control,London,2002
[10]Peretto L,Emanuel A E.A theoretical study of the incandescent filament lamp performance under voltage flicker[J].IEEE Trans.On Power Delivery,1997,12(1):279-288
[11]Wang F,Bollen M H J.Measurement of 182 Hz interharmonics and their impact on relay operation[C].Ninth International Conference on Harmonics and Quality of Power,Orlando,USA,2000
[12]Arrillaga J,Wastson N R,Bathurst G N.A multifrequency power flow of general applicability[J].IEEE Trans.on Power Delivery,2004,19(1):342-349
[13]张大海,徐文远.间谐波相序特性的研究[J].中国电机工程学报,2005,25(12):29-34
[14]郝江涛,刘念,幸晋渝,薄丽雅,陈卓.电力系统间谐波分析[J].电力自动化设备,2004,24(12):36-39
[15]钱吴,赵荣祥.基于差值FFT算法的间谐波分析p].中国电机工程学报,2005,25(21):87-91
[16]祁才君,王小海.基于差值FFT算法的间谐波参数估计p].电工技术学报,2003,18(1):92-95
[17]郭辉,傅成华,何春芳.基于短时傅里叶变换的电压间谐波分忻[J].电力系统通信,2008,29(186):66-68
[18]马秉伟,周莉,刁均伟.基于见代谱估计方法的间谐波检测[J].继电器,2005,33(3):25-27
[19]石敏,吴正国,尹为民.基于多信号分类法和普罗尼方法的间谐波参数估计[J].电网技术,2005,29(15):81-84
[20]丁屹峰,程浩忠,吕干云,占勇等.基于Prony算法的谐波和间谐波频谱估计[J].电工技术学报,2005,20(10):95-97
[21]王志群,朱守真,周双喜.基于Pisarenko谐波分解的间谐波估算方法[J].电网技术,2004,28(15):72-77
[22]向东阳,王公保,马伟明,张文博.基于FFT和神经网络的非整数次谐波检测方法[J].中国电机工程学报,2005,25(9):36-39
[23]裴源.基于神经网络算法的电力系统谐波分析方法[D].长沙:长沙理工大学,2007
[24]李凤婷,孙成祥.小波变换在电力系统中的应用[J].自动化仪表,2007,28(12):1-4
[25]钱峰,胡光岷.基于滑动时窗的小波变换实时算法[J].信号处理,2007,23(3):361-364
[26]Keaochantranond T,Boonseng C.Harmonics and lnterharmonics Estimation Using Wavelet Transform[J].Transmission and Distribution Conference and Exhibition 2002:Asia Pacific.IEEE/PES:775-779
[27]薛蕙,杨仁刚.基于连续小波变换的非整数次谐波测量方法[J].电力系统自动化,2003,27(5):49-53
[28]何磊.基于小波算法的电力系统间谐波测量[D].北京:华北电力大学,2006
[29]佟向坤,张淼.基于小波多分辨率分析的间谐波检测方法[J].自动化与信息工程,2008,3:10-12
[30]薛蕙,杨仁刚.利用Morlet连续小波变换实现非整数次谐波的检测[J].电网技术,2002,26(12):41-44
[31]赵凯.电力系统间谐波分析与检测方法的研究[D].北京:华北电力大学,2006
[32]刘桂英,栗时平.利用小波傅里叶变换的谐波与间浩波检测[J].高电乐技 术,2007,33(6):184-188
[33]丁屹峰,程浩忠,孙毅斌,严健勇.基于小波变换和Prony算法的间谐波参数辨识[J].上海交通大学学报,2005,39(12):2083-2087
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