Research On Characteristics Of Low Voltage Power Line Broadband Communication Channel

In order to improve the effectiveness and reliability of the local channel of the power user electric energy data acquire system and meet the growing demand for new power services,State Grid Corporation announced the “Low voltage power line broadband communication interoperability technical specifation” in June 2017,which indicates,in the future,low-voltage broadband power line carriers will likely be widely used in power user electric energy data acquire systems.However,at present,the existing research on the broadband characteristics of low-voltage carrier communication channels is insignificant in domestic and international related field,and there is no widely accepted channel model available for relevant researchers.In-depth study of the broadband power line channel model has great value in expanding theory and engineering practice.The main research achievement of this paper are as follows:For the two-core power line,the influences of the skin effect and the proximity effect on the per-unit-length resistance and inductance and the influence of the complex permittivity on the per-unit-length capacitance and conductance are first analyzed in this paper.Then,based on the low loss characteristics of power cables,the initial value of per-unit-length parameters is solved by electromagnetic simulation method,and a method for accurately solving per-unit-length parameters by using open circuit impedance measurement results is proposed secondly.In the end,the accuracy of the model is verified by building a power line test network with a bandwidth of30kHz-30 MHz,and the influence of the network structure on the channel characteristics is analyzed as well.For the three-core power line,based on the phase-mode transformation method,the per-unit-length parameters matrix is decomposed into common mode and differential mode parameters by using its symmetrical structure.Due to the finite element method electromagnetic simulation results,this paper also put forward a method for correcting per-unit-length parameters based on open-circuit impedance measurement in the mode domain.According to the theory of multi-conductor transmission line,the channel model of the three-core power line in the wide frequency is established,and the accuracy of the model is verified by building a test network.In order to simulate the channel characteristics of an actual low-voltage power cable in a laboratory environment,it is necessary to establish a power line lumped parameter model.First,the solved transmission parameters are converted into Y parameters to establish a ?-type equivalent circuit.Secondly,based on the vector fitting method,the passive equivalent circuit of each branch of the ?-type circuit is solved,and a lumped parameter model of a cable is created.On the basis of this model,the channel characteristics under various complex networks can be simulated.And the final accuracy check of the lumped model is verified by building a multi-branch test network.