Research Multiwavelet -FFT Power System Harmonic Detection

With the development of science and technology, more and more advancedpower electronic devices have been used in the electrical power system, such asthe new kind of transformers and switches. These devices are very important topower system. But it is obvious that they also lead to serious harmonic pollution.The harmonic pollution makes the insulation of transmission lines be aging andmakes the protective devices malfunction. They also influence the quality ofpower supply. So it is very important that we must filter the harmoniccomponents. The key of suppressing harmonic is that we can detect theharmonic components accurately.So this paper does a research on the method of harmonic detection in theelectrical power system, and makes the APF filter the harmonic components.This paper mainly studies the content as follows:(1) First of all, this paper does a deeply research on the method of harmonicdetection basing on unit wavelet, and builds some models of harmonic signal tosimulate. The results of simulation show that the method of harmonic detectionbasing on unit wavelet does not have the continuity and symmetry.(2) Secondly, the method basing on unit wavelet has some deficiencies, sothis paper does a further research on the method of detection basing onmulti-wavelet in order to improve the method of harmonic detection. Then thispaper builds the models to simulate by MATLAB. The results show that themulti-wavelet is better than unit wavelet on accuracy of detection. If using thiskind of the wavelet, we achieve the goal of improving the wavelet. But both unitwavelet and multi-wavelet could not show the information of the harmoniccomponents intuitively. This insufficient gives rise to some difficult. In order toimprove the methods of harmonic detection, this paper continue do a research onFFT. In the end, this paper combine multi-wavelet and FFT, and put forward amethod of multi-wavelet and FFT. Through the MATLAB, we find this methodcan detect harmonic components successfully, and achieve the goal ofimproving method of harmonic detection. (3) In the end, this paper puts the method of multi-wavelet and FFT into theAPF, and builds a model of system.The simulation results show that this APFapplying this method could filter the harmonic detection successfully, andachieve the goal of good power quality.