Research On Noise And Characteristics Of Low Voltage Power Line Channel

Low-voltage power line communication technology is widely used in all fields.However, the characteristics of low-voltage power line are complex and changeable,especially the attenuation characteristic, noise characteristic and impedancecharacteristic, which slow down the development of reliability and transmissionspeed. Since channel characteristic of low-voltage power line has a closerelationship with the modulation scheme, error correction of coding and the choiceof network topology, an in-deep study of the channel characteristic of low-voltagepower line has great meaning to solving the problem. This paper studies the noiseand attenuation characteristic on the basis of the study of former scholars, providingnecessary theoretical basis for in-deep understanding of the characteristics oflow-voltage power line.Firstly, the paper analyzes the noise characteristic of low-voltage power line,then builds the measuring circuit of low-voltage power line and the models ofbackground noise and pulse noise. The paper solves the parameters of autoregressivemodel in two ways and compares the advantages and disadvantages of the twomethods; Aiming at the innovative presentation of pulse noise model, the paperstudies the noise characteristics in two levels, characteristics of group-inside andgroup-outside, and verifies the model in time domain and frequency domain.Secondly, on basis of noise model of low-voltage power line, the paper usesLabVIEW and the PXI-5412of NI to design noise generator, to provide theexperiment basis of in-depth study of transmission characteristics and EMCenvironment of low-voltage power line.Thirdly, taking the influence of skin effect and dielectric loss on thetransmission of low-voltage power line into account, the paper builds a RLCGtransmission model aiming at three wires low-voltage power line. It also analyzesthe theoretical basis of RLCG model in detail, measuring the frequencycharacteristics of the basic unit length, and using the quantum genetic algorithm toidentify inter parameters. The experiment and simulation results indicated that theRLCG model can reflect the high-frequency transmission characteristics of powerline accurately.At last, we focus on the research of the low-voltage power line networkimpedance degeneration concerned about the real-time monitoring network topologychanges. On basis of RLCG model and FSV method, the paper presents a method toidentify the random pulse noise of electric equipment. The method is indicated toidentify the random noise accurately, in order to judge the change of topology. Accurate detection of the change of topology and informing the communicationequipment to adjust communication method and starting to use error correctiontechnology is very meaningful to improve the stability of low-voltage power line.