Study On Current Average Harmonic Detection Method Based On Instantaneous Reactive Power Theory

With the rapid development of electric power industry,more and more complex power electronic devices operate in the power grid system and couple with lots of non-linear loads,this cause the power grid system to be injected with a large number of harmonics,seriously affected the normal operation of the power system and its equipment.In order to quickly and accurately detecting harmonic currents in the power grid system,this paper proposes a current average harmonic detection method,which using MATLAB simulation software to build mathematical models,and verified in APF.The simulation results show that the improved harmonic currents detection method proposed in this paper has great practicability and high detection precision in harmonic detection,which has a good application prospect in engineering practice.The main research contents of this paper include:(1)Firstly,several common harmonic detection methods are summarized,then based on comparing and analyzing the advantages and disadvantages of each harmonic detection method,focused on the simulation research of i_p-i_q harmonic current detection method based on instantaneous reactive power theory.Selecting the appropriate LPF parameters and the harmonic current detection method mathematical model of i_p-i_q is built in MATLAB;Simulation analysis on the i_p-i_q harmonic current detection method under the different voltage conditions,the result demonstrates the effectiveness and feasibility of the i_p-i_q harmonic detection method.(2)Proposing a current average harmonic detection method based on instantaneous reactive power theory of i_p-i_q harmonic current detection method,which selects the integral delay period according to the least common multiple of required filtering harmonic frequency and constitutes the high performance filter in series with LPF;then importing the closed-loop feedback system of PD controller with anticipatory control and improving the detection accuracy of the detection method via adjusting the feedback parameter K.At last,building mathematical model in MATLAB,and comparing with i_p-i_q harmonic current detection method and traditional current average harmonic detection method.The simulation results indicate that this current average harmonic detection method has good performance in real-time detection and accuracy.(3)In order to further testify the availability of improved current average harmonic detection method,applied this method to the harmonic current detection model of APF.And compare it with the use of i_p-i_q harmonic detection method in APF.The results show that this current average harmonic detection method has more advantages,and have a broad prospect of application.