Study On Self-Adaptive OFDM Technology Of High-voltage Power Line Carrier Communication

Communication over high-voltage power line was the basis of our power system communications network, which played an important role in the control, security and stability operation. As the requirements of the high speed communication over the power system improved, the rate of the traditional method became less competent to satisfied the requirements—as we know the highest rate is only 64kbps. This dissertation is mainly focus on the self-adaptive OFDM system to be applied in Communication over high-voltage power line, which could increase the data transmitting.The signal transmission characteristics over high-voltage power line are the presupposition to be considered when the author prepares to design a brand new communication system. In this dissertation, the author does the research of the transmission characteristics and the power line noise. First, the author studies the structures of power line carrier, analyze the attenuation characteristic of the power line channel .Then the author researches the corona noise—NOT the Gaussian white noise existing in the normal channel, which is caused by the modulation of the frequency 150Hz , is the very role in the communication over the high-voltage power line .So the appropriate computer modeling of the corona noise compliant with the measurement results is built. By means of the measurements and the statistical analyses the author considers that the corona noise model is a correct and appropriate model, and the model is easy to realize.The most important thing to realize the self-adaptive OFDM is that the real-time algorithm, which is appropriate for the transmitting system and easy to realize. So the key research in this dissertation is the algorithm. The author studies the SNR threshold algorithm and build a sub-carrier allocation algorithm for OFDM. This algorithm is simple, appropriate to realize.In order to verify algorithm performance, the author combines transmission characteristics of high-voltage power line and the computer model of corona noise to build a testing model. The author compares the fixed sub-carrier allocation, SNR threshold algorithm and our algorithm. The results show our algorithm is appropriate for the high-voltage power line. The self-adaptive OFDM is very useful to increase the transmitted data rate.