基于AR谱估计和频谱分析的间谐波检测方法

自回归(Autoregressive,AR)谱估计方法频率分辨率高,但不易对间谐波幅值和相位实现精确计算;基于DFT的频谱分析方法能在辨识出各分量频率的基础上计算得到高精度的间谐波参数,但频率分辨率低。为此提出了一种结合这2种方法优势的算法来检测间谐波。首先采用基于最优窗加权修正的Burg算法估计出信号所含分量的大致频率,然后结合软件同步采样后的FFT频谱来分析计算各分量参数。同步采样时基波和谐波无泄漏,可以根据同步采样FFT谱线中只与间谐波有关的谱线来计算间谐波,此时间谐波谱线之间的相互干扰可通过利用间谐波谱线求解与间谐波参数有关的方程组来克服。最后对间谐波所靠近的基波和谐波谱线进行修正,就能保证谐波和间谐波参数精度都较高。实验证明,这种基于AR谱估计和频谱分析的间谐波检测方法能在分辨率和精度上得到兼顾。

An Interharmonic Detection Algorithm Based on AR Spectral Estimation and Spectrum Analysis

Autoregression spectral estimation methods have high frequency resolution,but interharmonics＇ amplitude and phase can not be easily accurately calculated.The spectrum analysis methods based on the DPT can be used to gel high precision interharmonic parameters with the accurate identification of interharmunic frequency as the premise,Imt thej have low high frequenc]resolution,so an algorithm combined with the advantages of two methods to detect the interharmonics is proposed.Firstly,Burg algorithm based on the optimal window weighted correction is adopted to estimate all frequencies of the signal,and then the result of FFT under software synchronous sampling is used to calculate all components＇ parameters.The fundamental wave and harmonics have no spectrum leakage under synchronous sampling,so the FFT spectrum line only related to interharmonics can be used to calculate interharmonics＇ parameters.At this time,the problem that interharmonic spectral lines may have mutual interference can be overcome by solving equations with interharmonic parameters.At last,the spectrum line of fundamental wave and harmonic parameters whose frequencies are close to interharmonics will be corrected in order to get high accurate parameters of both harmonics and interharmonics.Experiments show that the proposed interharmonic detection method based on AR spectral estimation and spectral analysis can taken both resolution and accuracy into account.