Research On Low Voltage Power Line OFDM Communication Technologies

Smart Grid is one of the main development direction of power network in the future, and the smart distribution grid is the key part. Reliable and safety distribution network must be based on the high-speed, integration, real-time and two-way communication system. Therefore, carrying out the research of distribution network new communication technology is of great significance in the future.Power Line Communication (PLC) technology has the advantages of wide coverage, small investment, without some rewiring, convenience of application, low cost of maintenance etc, which becomes the main communication mode of distribution network. However, it’s hard to realize the high-speed transmission of data in the network, because of the high complexity of power line channel structure. Therefore, it’s necessary to research a transmission technology, in order to improve the reliability and effectiveness of the power line communication.The Orthogonal Frequency Division Multiplexing (OFDM) technology provides an effective resolution to the high-speed transmission of data in the power line communication, because it has so many merits, such as high rate of data transmission, high capability to resist multi-path effect, more bandwidth efficiency, etc.The low voltage power line channel characteristics are analyzed from access impedance, signal attenuation, and noise. A channel model based on reflection phenomenon is proposed. Based on the analysis of the characteristics of low voltage power line channel, the whole schemes of designing an OFDM system are presented. The working principle of the system and the important parts are introduced in detail. The system is simulated by MATLAB. The results prove that the system can realize the reliable data transmission, and has good anti-disturbance performance. It is feasible and superior to make the OFDM technology applied to power line communication.To the problem of high Peak-to-Average Power Ratio (PAPR) in OFDM system, this paper proposes a low complexity and improved algorithm of combining grouping prejudgment technique with companding. The principle are also presented. The good performances of the proposed algorithm, including reduction of the PAPR and the BER with low complexity, have been checked by the simulation, which improves the performance of power line communication system effectively. With the further research of OFDM technology, and the deep development in the power line communication, the OFDM technology will have broad application prospects in the power line communication.