The Design Of Medium Voltage Distribution Network Communications System Based On OFDM

In recent years the distribution network develops rapidly. For the safety and stable distribution network, the medium voltage distribution network carrier communication technology based on the unique superiority is more and more important in the distribution automation. Along with Orthogonal Frequency Division Multiplexing technology’s development, the chip factory and institutes are interested in OFDM power line communication.Firstly, with the survey date of the distribution network channel model, the thesis analyzes the impedance characteristic, characteristic of attenuation and the noise disturbance. Compared with the different modulation systems, OFDM in power line communication manifests a huge superiority. OFDM utilizes several sub-carriers which are orthogonal with one another to transmit information, thus, the utilization of frequency band is enhanced greatly and the frequency selective fading and time variation in power line channel can be overcome effectively.Secondly, based on the request of lOkV distribution network communications, a mode is proposed to realize distribution automation, that is communication means base on OFDM power line communication. The hardware of PLC to the proposed mode are designed, that including the microprocessor module, modulation/demodulation module and computer’s communication interface circuit, periphery analogous circuit and so on. Because of the bad environment of distribution network, relaying strategy was designed. Some corresponding anti-jamming methods including hardware and software are taken to improve the reliability of PLC. Based on Communication protocol in our country, the protocol for the thesis was designed.