Research On Wavelet Packet Combined With Hilbert - Huang Transform In Medium Voltage Broadband Power Line Communication Noise Reduction

Although we can widen communication information transmission channels when using power line for communication signal transmission, but unable to avoid noise interference problem in this process. And comparing with the dedicated communication channel, the noise of power line communication signal is more serious. Therefore, based on the study of power line communication channel noise, wavelet packet decomposition and Hilbert-Huang transform are applied to the study of Power Line Communication noise reduction. And the main research contents are as follows:(1) Firstly, we studied the modulation and demodulation way of Medium-voltage broadband power line communication, and focused on the wavelet orthogonal frequency division multiplexing adapted the communication of the medium voltage broadband power line. Then we collected the communication signal data from Yunnan Power Grid Electric Power Research Institute, an integrated communication platform which is based on Medium-voltage broadband power line communication technology.(2) Wavelet packet decomposition is applied to the noise reduction of medium voltage broadband power line communication signals. First, we compared different wavelet packet to determine which one is the optimal wavelet packet basis for medium voltage broadband power line communication signal denoising. At the same time, in order to reduce the threshold of wavelet packet noise reduction process, the threshold of the choice of the signal generated by the oscillation or deviation, the singular value decomposition is applied to the wavelet packet decomposition and noise reduction.(3) Based on the analysis of the shortage of wavelet packet decomposition, the Hilbert-Huang transform is introduced to the noise reduction and noise analysis of the medium voltage broadband power line communication signal. In the process of empirical mode decomposition, due to the intrinsic mode function of the original signal which contains the singular point, the empirical mode decomposition and empirical mode decomposition are studied. According to the characteristics of medium voltage broadband power line communication signals, a wavelet packet based on correlation coefficient is proposed to reduce the empirical mode decomposition of the wavelet packet based on the empirical mode decomposition. During analyzing the different noise reduction algorithm for medium voltage broadband power line communication signal noise reduction effect analysis, we found that the distribution in medium voltage power line in the vicinity of the high voltage power line of IP broadband power line communication signal generated interference, and this kind of interference is relevant with the voltage levels and power line position.