结合粗调和细调的电力系统谐波分析算法

An Algorithm With Coarse Adjustment and Fine Adjustment for Power System Harmonics Analysis

为了解决FFT(快速傅里叶变换)在频率波动时存在误差的问题,提出结合粗调和细调两步调整的电力系统谐波分析法。该算法根据采样时间长度决定使用FFT或加汉宁窗插值谐波分析法快速获得信号较为准确的谐波分析结果,作为算法中的粗调部分;并通过Levenberg-Marquardt算法对所得谐波分析结果进行细调。该算法精度高,对采样时间长度要求低,根据采样时间长度选择FFT或加汉宁窗插值和Levenberg-Marquardt算法提高了收敛速度,是电力系统谐波分析的有效算法。对该算法受白噪声影响的仿真分析表明,算法受白噪声影响大,随信噪比增加误差减少,到80dB左右算法精度有保证。

For solving the problem that Fast fourier transform （FFT） algorithm has error in the condition of signal frequency fluctuation, power system harmonic analysis algorithm with coarse adjustment and fine adjustment is proposed. FFT algorithm or Hanning-windowing interpolation harmonic analysis algorithm is selected according to sampling time length, and used to obtain accurate harmonic analysis result in short calculated time, and is taken as coarse adjustment part of the algorithm. After then, Levenberg-Marquardt algorithm is used to adjust the result by coarse adjustment algorithm, and which is fine adjustment part of algorithm. The proposal algorithm has high accuracy, low requirement for sampling time length, and the selection of FFT or Hanning-windowing interpolation algorithm and Levenberg-Marquardt algorithm increases convergence speed. So it is an effective algorithm for power system harmonic analysis. After analysis of algorithm influenced by white noise, it is indicated that the algorithm is seriously influenced by white noise; error decreases with the increase of signal to noise ratio （SNR）, the algorithm has high accuracy when SNR is approach to 80dB.