Research On Impedance Matching Of Power Line Carrier Communication In Medium Voltage Distribution Network Under Network Mode

The steady development and continuous development of intelligent distribution network construction puts higher requirements on distribution automation.Power line communication(PLC)is a communication method that uses power lines to transmit data.Due to its unique advantages such as low cost and high flexibility,it is a main choice of medium voltage distribution automation communication network.However,due to the complicated topology of the power line of the medium voltage distribution network and the time-varying load,the input impedance presents a large difference,the channel environment is bad,and a serious impedance mismatch problem is caused in the communication process,which leads to serious power attenuation of signal transmission and greatly affects the quality of communication.In this paper,the impedance matching method for single-point and multi-point communication of medium voltage distribution network PLC is deeply studied,the topic selection has important theoretical significance and engineering practical value.Firstly,the reason of the reflection of the signal is theoretically analyzed by the power line transmission.On the basis of this,combined with the network quality factor and the Smith circle impedance matching network design method,an improved multi-structure impedance matching circuit design method is proposed.Secondly,based on the principle of local reflection,a PLC channel model of medium-voltage distribution network with power attenuation as the index is built.On this basis,the impedance matching relationship between each carrier device in the simple network mode of one master and two slaves is analyzed.Considering the tightness between the optimized target node and the adjustable impedance,the differential localization method is used to define the range of the optimal independent variable,and a three-point communication impedance matching method based on differential localization is proposed.The related examples show the correctness and effectiveness of the method.Finally,based on the deduction of simple network impedance matching relationship,combined with the actual middle-voltage distribution network topology and communication mode,an optimization algorithm of PLC impedance matching for multi-point communication in complex network mode is proposed.The algorithm firstly divides the complex network into several small areas that can be matched,then uses the particle swarm algorithm to coordinate and optimize the impedance matching in each small area.Finally,the small areas are cascaded back to the original network through relay.The simulation shows that the proposed method is effective in solving the impedance matching problem of complex networks.