Research On The Method Of Harmonic Detection And Compensation In Power System

With the development of the power electronics,more and more nonlinear loads are produced.And the problem of harmonic pollution becomes more and more serious.However,the customer requires a higher quality of the electronic with the precise instruments springing up.Therefore,research on harmonic analysis method,which has better effect and higher precision,real-time and accurate detection and analysis of power quality parameters,and provide reliable basis for harmonic in power system of governance,has very important significance.First,this paper introduced the theory of harmonic in power system as a whole,including basic knowledge of harmonics 、 the harmonic measurement method and its measurement standard in the state and several traditional harmonic detection methods are analyzed and the methods are analyzed.Secondly,the paper introduces working principle of Empirical Mode Decomposition(EMD)and Complementary Ensemble Empirical Mode Decomposition(CEEMD),by combining the theory and simulation,proved the superiority of CEEMD;after introduced the Hilbert Transform(HT),and combined HT with CEEMD,put forward a kind of harmonic detection and analysis method — — CEEMD-HT algorithm.Through simulation experiments,the results show that the algorithm can get the information of instantaneous frequency and instantaneous amplitude of the target signal,and has good ability of harmonic detection and analysis.Then,derived the theory of instantaneous power theory and instantaneous reactive power theory,and it is concluded that in the case of three-phase voltage distortion,the direct application of the instantaneousreactive power theory to the detection model of the stored larger detection error.In view of the problems in the model,combined with the characteristics of CEEMD,proposed the C-EEMD algorithm.This algorithm can deal with the voltage distortion,get the fundamental voltage;Combining C-EEMD with the p-q detection model,an improved p-q detection model is formed.The comparison the simulation analysis of improved p-q detection model and i_p-i_q model,the detection results show that the improved p-q detection model can effectively solve the problem of voltage distortion on the impact of the system,and the detection accuracy is higher than i_p-i_q detection model.Finally,this paper analyzed the basic principle and the types of filters,then analyzed the main circuit and control strategy of the active power filter,and built the shunt active power filter model,improved p-q detection model is applied to the harmonic detection module of the active filter.The simulation results show that the active filter can realize the real-time compensation of harmonic current effectively,and the effect is good.