Study On The Analysis Methods Of Harmonics In Power System

With the development of Power Electronic Technology, a lot of inverter equip- ments are applied in the current power system. Since many power electronics equipments and nonlinear loads are accessed, more and more harmonics and interharmonics occur in power system. The presence of harmonics may deteriorate the power quality,and lead to further effect for electrical equipments and power grids. As the more and more attention to power quality, the accurate harmonic analysis for power system is very important.In this paper, Fourier Transform algorithm is used for harmonic analysis, and some improved methods such as windowing and interpolation algorithm based on FFT, multiple modulation zoom analysis based on complex analytic band-pass filter(improved ZFFT) are introduced. Windowing and interpolation algorithm based on FFT is one of those widely used in harmonic analysis, and for the variations of fundamental frequency , modify the sampling frequency , and the improved ZFFT in settlement to small intervals of frequencies is an improved algorithm with windowing and interpolation algorithm.Finally, the relative spectrum analysis chart and the calculation results of detailed frequencies amplitude and phase are obtained by MATLAB/Simulink software and the chosen algorithms. It is showed that the effect of Hanning window is better than Hamming window, and the accuracy of double interpolation algorithm is higher than the single interpolation algorithm. The accuracy of harmonics analysis is improved by modifying the sampling frequency. The improved ZFFT can tell the harmonic components whose frequencies are close to each other. It is better than other algorithms. The improved ZFFT is used in the harmonics analysis, and achieve the good result.