基于AR谱估计和最小二乘法的间谐波检测方法

he problem of interharmonics in electric power system is becoming increasingly severe. It is necessary to measure the interharmonics exactly. Interharmonics are defined as the signal that have frequencies between two harmonic. Interharmonics frequencies are not integermultiple of the fundamental frequency, and interharmonics amplitudes are far less than fundamental amplitude and harmonics amplitudes, which mean hign sensitivity to desynchronization problems, so it's difficult to estimate interharmonics. In this paper, a method for interharmonic measurement is presented based on AR model spectralestimation and Least square technique.Through using the Least square technique, the low amplitude signals can be estimated sequentially;inaddition,the application of LS can estimate the amplitudes and phases of the signals exactly. The results of experiments show that the proposed method can estimate the interharmonics exactly, even if the interharmonics frequencies are close the fundamental frequency and interharmonics amplitudes are far less than fundamental amplitude; and can measure high order interharmonics with lower sampling frequency.