小波分析方法及其在電力系統(tǒng)中的應(yīng)用課件-文庫吧資料
2025-01-01 11:51本頁面
【正文】 析(Multiresolution Analysis)分解與重構(gòu)zScale coefficient:zWavelet coefficient:zApproximation:zDetail:zSignal:離散小波分解圖 1離散小波分解圖 2 示例： EMI信號(hào)分析Simulated EMI noiseFFT analysisCWT analysisDWT analysis6. 小波包變換簡(jiǎn)介小波包空間劃分U00 ( V0 )U10 ( V1 ) U11 ( W 1 )U20 ( V2 ) U21 ( W 2 ) U22 U23 U30 (V3)U31 (W 3)U32 U33 U34 U35 U36 U377. 電力系統(tǒng)應(yīng)用 由于小波具有優(yōu)良的分析奇異信號(hào)能力，小波理論已經(jīng)在電力系統(tǒng)中被大量應(yīng)用。s window could vary. For example, it uses long timewindow for lowfrequency signal and short timewindow for highfrequency signal. 4. 連續(xù)小波變換（ CWT ）zContinuous Wavelet Function（連續(xù)小波函數(shù)）zDilation, contraction and translation of wavelets （小波的伸縮和平移）zContinuous Wavelet Transform（連續(xù)小波變換）zInverse CWT （連續(xù)小波逆變換）z參考： MATLAB的小波工具箱連續(xù)小波函數(shù)z The dilation, contraction （伸縮） and translation （平移） of mother wavelet results in a set of continuous wavelets:z a is called scale factor（尺度因子，與頻率有關(guān)）z b is called translation factor（平移因子，與時(shí)間有關(guān)）伸縮和平移連續(xù)小波變換zFor signal f (t) ? L2(R) , its continuous wavelet transform (CWT) is:zWherezWf(a,b) is continuous wavelet coefficient （連續(xù)小波系數(shù)）CWT 示例連續(xù)小波逆變換zSignal f (t) can be reconstructed（重構(gòu)） by its continuous wavelet coefficients:zThis is called Inverse Continuous Wavelet Transform.MATLAB的小波工具箱zwavemenu5. 離散小波變換（ DWT ）zDrawback of CWT （連續(xù)小波變換的缺點(diǎn)）zDiscrete Wavelet Transform （離散小波變換） ......zExample: EMI noise analysis （示例： EMI信號(hào)分析） 連續(xù)小波變換的缺點(diǎn)zContinuous wavelet functions are correlated.zMathematically speaking, the wavelet functions are not an orthogonal base （不是正交基） .基，正交基zIn a 2Dimension space, there are 3 vectors :zThe following is an orthogonal ba
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