The traditional fast Fourier transform (FFT) is mainly applied to the analysis of the steady-state harmonic signals but is difficult to gain the time local information, and it shows big errors in the analysis of mutation signals or high frequency interference signals; the discrete wavelet transform (DWT) is particularly suitable for the non-stationary signals and transient signals, but shows lower accuracy than FFT in analyzing the steady-state harmonic signals. One analyzing strategy of power system harmonics based on FFT and DWT using db20 is presented considering advantages of both FFT and DWT. First of all, the power system harmonic signals are decomposed into low frequency part and high frequency part through the DWT, and then it is analyzed by FFT and db20 wavelet respectively. The strategy is proved effective and applicable by MATLAB simulation, which achieves the desired results. rnThis work supported by National Natural Science Foundation of China (No. 60772006).%传统傅里叶变换( FFT)主要应用于稳态谐波信号的分析,却难以得到时间局部信息,且对于突变信号或高频干扰信号的分析误差较大.小波变换(DWT)特别适合于不平稳信号和瞬变信号的分析,但对于稳态谐波的分析精度不及FFT.结合FFT和DWT中db20小波各自的优势,提出了一种基于FFT和db20小波变换的电力系统谐波联合分析策略.首先将电力系统谐波信号通过离散小波变换分解为低频部分和高频部分,再分别运用FFT和db20小波进行分析.算法经Matlab仿真,获得了预期结果,证明该策略在电力系统谐波分析中具有可行性和实用性.
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