Research On Medium-voltage Power Lines Buried Cables Broadband Communication

Distribution network automation is an effective way of constructing smart power distribution network. The distribution network communication system is the key technology of distribution network automation. Compared to the backbone communication network, the communication technology development of access network is lagging behind. Medium-voltage power line communication is an important communication means of smart power distribution network. And it can be used as an effective complement of optical fiber technology to help form a full-coverage communication network. Therefore, it has an important practical application value to research on the 10 kV medium-voltage buried cable broadband communications.Aimed at the current cable laying situation of urban distribution network line and the characteristics of the power line broadband communication, the phase conductor and shielding layer of medium-voltage buried cables were used as the broadband communication channel firstly. The transmission characteristics and communication performance of this mode were researched. The amplitude-frequency and phase-frequency characteristics of such a communication channel were measured and analyzed. Based on transmission line theory, a channel transmission model of urban medium-voltage buried cables was established, and model parameters were set according to measured data. The simulation transmission characteristic of the transmission line model and buried cables model were compared with the measured results. It validated that the buried cables model was more accurate than transmission line model in the buried cables simulation communication system. Based on the built model and according to IEEE P1901 standard, the orthogonal frequency division multiplexing(OFDM) communication system was simulated, and the simulation results show that the bit error rate of the buried cable with length of 1km is lower than7-10; Based on the characteristic of OFDM technology which can dynamically allocate bits, the system rate in different signal-to-noise ratio were calculated. By constructing buried cables rate test system, the actual rate in several transmission distances and different channels were tested. The measured results showed that the actual transmission rate of the buried cable with length of 300 m reached about 70Mbits/s. Both simulation research and actual measurement have shown that the buried cables can meet the communication requirement of distribution network automation, thus in allusion to the situation that the paths are not suitable to lay the optical fiber cable the buried power cables can be used for broadband communication.