论文标题:谐波小波在电力系统（间）谐波检测中的应用研究
Research on Application of Harmonic and Inter-harmonic Wavelet Transform to the Harmonic Analysis of Power System
论文作者
论文导师 李天云,论文学位 硕士,论文专业 电力系统及其自动化
论文单位 东北电力大学,点击次数 100,论文页数 60页File Size2033K
2008-03-01论文网 http://www.lw23.com/lunwen_113383602/
Dyadic Harmonic Wavelet;; Generalized Harmonic Wavelet;; Inter-Harmonic;; Least Squares Fitting
近几十年来,随着各种电力电子装置(主要是一些非线性设备)的广泛应用,使得公用电网的谐波污染日益严重,不仅含有频率是基频整数倍的谐波,还存在大量非整数倍的间谐波。谐波间谐波引起电能质量下降和各种故障和事故,因此,对谐波进行检测和分析是十分必要的。 谐波小波是近年来发展起来的一种新的信号处理工具,它是一种具有严格的盒形频谱特性和简单的解析表达式的小波,由小波的频域上构造得到。谐波小波分为二进谐波小波和广义谐波小波,有一种基于快速傅里叶变换(FFT)及其逆变换(IFFT)的快速算法,在数值上可以实现,算法速度快,精度高,具有很好的工程实用价值。 一直以来,谐波小波在机械振动领域应用广泛,在电力系统中则鲜有见报。鉴于谐波小波频段的任意“细化”能力,本文将其应用于噪声环境下电力系统谐波间谐波检测之中。首先对谐波小波进行加窗处理以减少频谱Gibbs现象,然后运用谐波小波方法实现各谐波分量的分离,计算出各谐波分量的瞬时幅值和频率,并对结果进行最小二乘拟合以提高精度。 大量的仿真结果表明:谐波小波方法在电力谐波/间谐波分析中是准确有效的。
Recently, with the widespread application of various kinds of electrical and electronic devices (mainly some non-linear equipment), harmonics pollution is becoming more and more serious, which contain harmonics and massive inter-harmonics. Inter-harmonic is a kind of the harmonics which are not an integer of the fundamental frequency component. Harmonics and inter-harmonics cause power quality to come down and different kinds of faults and accidents to happen often. So, harmonic for the detection and analysis is very necessary. Harmonic Wavelet is newly proposed and becomes a new signal-processing tool. With the launching on the spectrum of wavelet, the harmonic wavelet is structured, which has strict box-like spectrum and simple function expression. Wavelet divided into dyadic harmonic wavelet and generalized harmonic wavelet. It has a fast algorithm based on the Fast Fourier Transform (FFT) and its inverse transform (IFFT), which can be realized in the numerical. The algorithm has characteristics of faster speed and higher precision and better practical value. The harmonic wavelet widely applied in mechanical vibration area, is adopted in this paper to deal with the harmonic and inter-harmonic problem in power system., in view of its ability of detail frequency section. Firstly, in order to reduce the impact of Gibbs phenomenon in spectrum, a step of adding window process is employed. And then, the harmonic signal is decomposed by harmonic wavelet transform (HWT) and the instantaneous amplitude and phase of harmonic components are identified; furthermore, in order to increase accurate, the amplitude and phase of each harmonic components are calculated by least squares fitting method. Numerical results show that the presented approach is an effective one with high accuracy.
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