Research On Detection Method Of Complex Harmonics And Interharmonics In Power System

With more and more nonlinear loads in power system, the complexity of harmonic components in power system also increases. The harm caused by harmonic and interharmonic has become an important factor affecting the safe and stable operation of power system and the docline of power quality. Therefore, in-depth research on harmonic and interharmonic problems in power system, overcoming the shortcomings of traditional detection methods and putting forward more accurate and effective detection methods are the necessary premise to effectively control harmonic and interharmonic pollution and improve power quality.Firstly, this paper analyzes the problems of Fourier harmonic analysis method. Secondly.the improvement effects of different window functions and bispectral interpolation algorithms on its defects are discussed respectively. Finally, the simulation shows that the windowed interpolation algorithm can suppress the spectrum leakage and fence effect to a certain extent,and points out the shortcomings of this method. Through the in-depth exploration of the above problems, two solutions are proposed:(1) This paper presents a harmonic and interharmonic detectíon algorithm based on DFT and group harmonic energy recovery theory. Firstly, the number of harmonic and interharmonic components is determined accordimng to the spectrum analysis results of DFT signal; Socondly.the group harmonic enargy recovery theory is used to recover the collapsing energy around the main frcquency, and the sampling points are adjusted to make the sampling window approximate the whole period samplíng. so as to reduce the spectrum leakage; Then, the estimated values of harmonic and inaruneters parameters are obtained by using the enengy recovered by group harmonics. Finally, through simulation comparison and analysis, the effectiveness of the algorithm in analyzing complex harmonie and interharmonice signals with similar frequeney, as well as in the case of noise interference and fundamental frequency fluetuntion is verified.(2) In this paper, a more accurate harmonie and interharmonie combination optimizatlon algorithm based on multi-component spectrum superposition and quati Newton method is proposed, Finstly, the frequency estimates of complex harmonic and interharmonie sigrals are measured by using the multi-component spectrum superposition algorithm, and the objective function about umplude and phase mgle is constructed by using the frequency parameters.Then,the dbjective functáon is terwtively optimsed by using the exxellent comwengence of mbfgs algorthm. By seting the tnitial vahue d iterative accuracy,the approximate min imumpont, that is ,the snpltude and phage estimate) of hemonát or interhemonác components, is finally obtained. Finally,throngh simulation comparison and analysis, it is verified that the algorithun is effective in measming the time of single interhamomic or interhurmonic par with frequmncy adjacent to the fumdamental wave, and las certaim advantagrs in measurement accuscy and mtinoise.