The Research Of Harmonic/Inter-Harmonic Detection Algorithm In Power System

With the widely use of non-linear equipments,the problems of harmonics havebecome more complicated in power system. And it caused serious pollution to the powerquality. A mass of the harmonics/inter-harmonics may make the voltage or currentwaveform distort and result in the wrong running of relay. So it may bring great harm tothe safe operation of power system. Therefore, the harmonic control in power system is anurgent task.The paper studies the accuracy algorithm of harmonics/inter-harmonics detection inpower system on the basis of harmonics/inter-harmonics analysis. It provides the basis forharmonic treatment and improves the power quality significantly.It produces false spectrums for harmonic detection with multiple signal classificationand its derivative algorithm. And in the case of low SNR, it reduces the resolution and hasa significant impact on detection accuracy. MUSIC algorithm based on noise subspacedecomposition inhibits greatly the phenomenon of false spectrum. And it achieves highprecision estimation of harmonic/inter-harmonic in the case of low SNR.At present, the detection algorithm for harmonic/inter-harmonic with independentcomponent analysis needs some prior knowledge. And the estimation accuracy of phaseand amplitude is not high enough. The EVD-FastICA algorithm based on eigenvaluedecomposition and independent component analysis can achieve the high-resolution andhigh-accuracy detection of harmonic/inter-harmonic without any priori knowledge,especially for amplitude and phase.In case of low SNR, it makes the isolated signals waveform distortion and can noteven detect the small value inter-harmonic components with independent componentanalysis. LSM-FastICA algorithm determines the fundamental and harmonic by using FFTand least squares method, and constructs observation matrix, then detects inter-harmonicwith independent component analysis and least squares method. In case of low SNR, thealgorithm can also achieve the inter-harmonic detection without any priori knowledge.