Research On The Improving Electric Power Quality Based On The Harmonic Detecting Method Of Mathematical Morphology

With the wide application of power electronic technology, the problem ofharmonic pollution is more and more serious. In the power grid, the existing of theharmonic currents threats the stability of power grid operation and equipment safety.Therefore, the detection of harmonic current in power grid is of great significance.The traditional low-pass filter cannot yet meet the requirements of harmonic detectionaccuracy and rapidity. In this paper we introduce the mathematical morphology filterinto the harmonic detection. The mathematical morphology filter is a nonlinear filter,which has been widely using in the fields of image processing and analysis, computervision and pattern recognition and so on. Recently, it has been found in the electricpower system. This paper focuses on the harmonic current detection in the power gridBased on the research of the basic theory of mathematical morphology, thispaper lays emphasis on the application of the mathematical morphology filter in thei p iqharmonic current detection, and verifies its filtering performance through thesimulation experiments. Firstly, the mathematical morphology filter replaces thetraditional low pass filter in the method of thei p iqharmonic current detection. Themedian filter of the mathematical morphology filter is designed by selection theelement length of the two-level structures in the morphological opening operation andclosing operation. Then, the parameters of the cutoff frequency and the order of thelow-pass filter are determined by simulation experiments of thei p iqharmoniccurrent detection. Finally, the mathematical morphology filter basedi p iqharmoniccurrent detection model is constructed, and the filtering performance is compared withthat of the traditional low pass filter. The simulative results show that the rapidity andaccuracy of the mathematical morphology filter is superior to that of traditional lowpass filter, also indicate that the feasibility to introducing the mathematicalmorphology into the harmonic current detection.