Research Of Harmonic Detection System Base On Wavelet Packet Transform

Wit h the r apid de ve lopme nt of global economy, the demand of powe r isalso constantly increasing, the requirements for power quality has graduallyimproved.With the fa st expand of power ele ctroni c t echnology, powe relectronic devi ces are widely used, the poll ution of grid envi ronme n tincreasing serious caused by the har monic. So quickl y and a ccur ate ly detec tthe harmonic content of power system, whi ch has a gre at signi fica nce ofhar monic poll ution supervis i on and ma nage ment, har monic suppre ssi on andcontrol, protecting the power grid operation economic and stability.This pa pe r fi rst i ntr oduces the ba sic c o ncepts of power sys te m har monic,as well as the research status of domestic and fo reign, in dept h e xploratio nof the basic pri nciples of Fourier tr an sfor m, s h ort ti me Fourier t r ans for m,wa velet t rans for m a nd wa velet pac ket transform harmonic detectionalgorit hm and comparing these al gori thm. Thi s paper pr oposes a wa veletpacket filter bank reconstructing al gorit hm by analyzing the spectr u maliasing problem in harmonic detection, and simulating through MATL AB.The simulation results show t hat t he i m pro ved wa velet packet al gorit h m canma ke the freque nc y bands of har monic signal di vide evenl y, can extractbetter ti me-frequency char acteristi cs of si gnal, i mpr ove the detecti onaccur acy of har monic si gnal and make the wavel et packet deco mposition ofband i n accor dance with the size of the frequency of continuous ar ranged,ma ke it has higher visual.Acc ording to t he r equir e me nts of har monic det ection, t h e har d war e ofhar monic detect ion de vice has det er mi ne d, the progra m of har moni cdetecti on syst e m base d on DSP ha s pr opos ed. By c o mpari son of thepara met er of electr onic c o mponent s, desi gni ng modular hardwa re circuit s,including signal c ondi tioni ng circuit s, pha se l ocke d l oop s ync hronizati oncircuit, data pr ocessing module and communication i nter face cir cui t and soon. In the soft design, using the way of combining C language and assembl ylanguage to de sign the DSP mai n pr ogra m and data coll ec tion proc edur es,the wavel et packet co mpiled in DSP, i mproving the enforceabili ty of t heproc edure code.Finally, using the FFT, wavelet transform and wavelet pac ket i mpr ove algorithm to simulate st eady harmonic signal, non-steady harmonic signal,transient harmonic signal a n d t he har mo ni c sig na l with noise by MATLAB,by comp aring analysis, the si mulation result s show t hat the wavelet packettrans for m not onl y can dete ct the ori ginal signal in the fundamental andhar monic compone nts, but al s o has hi gh detecti o n accur acy, which i s mostsuita ble i n t he dete ction of har moni c s ignal.