Simulation Study Of Wavelet Neural Network Harmonic Detection Method And The Active Filter

This paper summarizes the development of harmonic detecting technology by software or hardware and the principle of active power filter for harmonic compensation at first. On the basis of analysis and synthesis to Wavelet Transform theory and Neural Network theory, the paper has designed a WNN-Wavelet Neural Network, presents build process, training algorithm and the principle to choose and initialize weight, threshold parameters to this network. Using the theory of analogy paralleling filtration type of harmonic detecting equipment, the thesis constructs a new harmonic detecting method based on WNN. According to the characteristics of harmonic in power system and by means of analysis and research to the form approach of training samples, this paper has carried out simulation research to the proposed harmonic detecting method based on WNN by programming. The simulation result indicates that this new harmonic detecting approach is feasible and effective.Then simulation models of i ,i algorithm based on the theory of instantaneous reactive power and hysteresis comparator control method are given in SIMULINK environment of MATLAB software with the help of power lib toolbox of MATLAB, which aims at simulating an active power filter system. Simulation to the condition of load changing suddenly is researched as emphases. The results not only indicate that the simulation method and simulation mode implemented are efficient but also prove that this approach has a faster dynamic response.On the basis of system simulation in SIMULINK, a set of software and hardware realization scheme applied to TMS320LF2407A DSP chip is brought forward. And experiment research is made further more. Several key problems in software designing are introduced with emphasis, including the digital implementation of i_p, i_q algorithm calculating induction current, the generator scheme of PWM waveform and the implementation of digital PI controller using to control voltage in DC side by DSP.Finally the digital APF system is tested. The experiment result indicates that the whole experimental device based on DSP can eliminate harmonic effectively caused by nonlinear load.