Research On Analysis Method Of Harmonic And Inter-harmonic Of Wind Power Grid Connection Based On SST

In recent years,with the grid connection of wind power and a large number of access to power electronic equipment in China,a large number of harmonics/ interharmonics have been produced in the power grid,which not only seriously affects the stability of the power grid,but also brings serious harm to the safe and economical operation of power equipment.This paper studies two harmonic/inter-harmonic analysis methods of synchrosqueezing wavelet transform(SWT)and Fourier based synchrosqueezing transform(FSST),and analyzes the current harmonics/interharmonics at wind power nodes by using these two synchrosqueezing transformations(SST).The details are as follows:(1)The traditional harmonic/inter-harmonic analysis methods are analyzed.The basic principles of traditional harmonic/inter-harmonic analysis methods such as fast Fourier transform(FFT),wavelet transform(WT)and Hilbert Huang transform(HHT)are analyzed,and the analysis effects of different methods in harmonic/inter-harmonic analysis are discussed.(2)Two harmonic/inter-harmonic analysis methods of synchrosqueezing transform are studied.SWT and the FSST are applied to the analysis of harmonics/inter-harmonic in power grid.The principle of SWT and FSST are analyzed.The time-frequency analysis results of the two methods are compared and analyzed,and the mechanism of anti-mode aliasing and anti-noise interference is revealed.Two kinds of synchrosqueezing transform are used to analyze the common harmonics/interharmonics in power system,and compared with the traditional method to verify the effectiveness of the proposed method.(3)The harmonic/inter-harmonic of grid connected current are analyzed.The harmonic model of doubly fed wind turbine is established to study the generation mechanism of harmonic/inter-harmonic,and the harmonic current of wind power grid connected at different wind speeds and different grid connected nodes is analyzed by using FSST to study the distribution law of harmonic/inter-harmonic of wind power grid connected.(4)Harmonic/inter-harmonic analysis of actual grid data under sub-synchronous oscillation.In view of the characteristics of a large number of power system monitoring data,using synchrosqueezing transform to analyze the actual power grid data under sub-synchronous oscillation of Hami.On this basis,the time series data mining algorithm is used to study the distribution law of harmonics / inter-harmonics under the sub-synchronous oscillation and to mine the effective information in the sequence.