Research Methods And Practical Application Of Inter-harmonics

Nowadays,with the wide use of power electronic devices,A lot of load for example,high power rectifier devices,The frequency conversion device,industrial electric arc furnace.In ord to power system waveforms are becoming more and more complex,Inter-harmonic increased significantly,the result produced more and more serious influence on safe operation of power system and the subscriber.In order to make the power system more and more safe,the harm caused by inter-harmonics has been paid more and more attention.In the project will encounter many problems are caused by interharmonics,interharmonics analysis method to become the focus of scholars research.This paper first briefly introduces the research significance and the research status of inter-harmonics,and introduces the principle of the different inter-harmonics analytical methods.To introduce the advantages and disadvantages of various analytical methods in the practical application.Through the introduction of the main power system interharmonic sources,and the mechanism of interharmonic sources generate interharmonics, then get the connection inter-harmonic frequency with inter-harmonic source.this paper briefly analyzed main harm of Interharmonics in power system.Through the understanding of inter harmonics generation and harm, can help analysis of the problem in the actual projects.Then this paper introduces the fourier transformation principle and problems in practical application, and the simulation analysis is carried out,After the introduction of spectrum correction theory which is reduce the error of the fourier transformation. And introduces several window functions and analysis methods of spectrum correction. Based on the theory of spectrum correction,To detail analysis of the interpolation principle,and analysis frequency,amplitude,phase correction principle. Then compare the result to add different types of window functions for simulation analysis, and analyzed the influence the correction accuracy with different window functions.After given an improved spectrum correction method.Through simulation analysis,compared error with the interpolation method and the phase difference method to prove this method advantage.Through the spectrum correction method analysis and simulation, we get the applicable range of the spectrum correction method in practical engineering.it can analysis the inter-harmonic components at a distance.Because the actual project will encounter a particularly dense band, so this paper presented a spectrum zoom methods to analysis inter-harmonics, and introduce the traditional Zoom-FFT principle and steps.To suppress the traditional Zoom-FFT shortcomings,the new method is presented based on complex analytic band-pass filter,. By simulation analysis of the dense inter-harmonic spectrum, after this method,then spectrum correction based on interpolation method,it can the analysis and correction the dense inter-harmonics, so it can be applied to practical application.Finally,combining with the practical engineering,finding out the cause of filter branch fusing,verify the applicability of the method of spectrum correction and refinement.