Research On Carrier Communication Network Of Power Distribution System Based On OFDM Technology

Smart distribution network is an important part of the Smart Grid.The realization of power line carrier communication in medium voltage distribution network has important practical value for making the smart distribution network more flexibility and simplicity.In this paper,the distribution system carrier communication network based on OFDM is deeply researched,which is as follows:Firstly,the hardware circuit design,program design and its supporting software development of the medium voltage power line carrier communication device based on OFDM is finished.In the actual test process,the hardware device was upgraded three times,and the device's performance is improved.Secondly,through the analysis of the medium voltage power line carrier channel and the actual field test,it is obtained that there are two effective ways to enhance the performance of medium voltage power line carrier communication device,that is to reduce the carrier signal attenuation or to avoid the frequency selective fading pits of the carrier channel.In practical application,the impedance matching between the coupling device and the carrier communication device plays an important role in reducing the attenuation of the carrier signal.A precision digital adjustable resistor is terminated in the carrier device.According to the parameters of the actual coupling device,the MCU control unit adjustes the digital adjustable resistor's value to achieve the impedance matching.In this way the signal attenuation is weakened.And in order to effectively avoid the frequency selective fading pits of the carrier channel,an adaptive optimal subchannel selection algorithm which is suitable for medium voltage carrier communication is proposed.This algorithm can dynamically adjust the carrier subchannel to achieve the optimal allocation of carrier frequency.In order to verify the effectiveness of the algorithm,the algorithm is embedded in the carrier communication device,and the measured result is ideal.Thirdly,the actual medium voltage distribution network has a large number of communication nodes,and it is very complicated.Besides,the expansion of the communication network in later period is highly demanded.In order to solve the above problems,a flexible networking approach is proposed,that is to establish star carrier communication firstly,and then to construct the tree shaped carrier communication network,cover all communication nodes gradually.Finally,using the self-designed medium voltage power line carrier communication device to run on the actual power distribution line,the communication effect is ideal.