低压电力线噪声及信道特性的研究

发布时间：2018-03-20 14:47

本文选题：低压电力线通信　切入点：噪声特性　出处：《哈尔滨工业大学》2014年硕士论文　论文类型：学位论文

【摘要】：低压电力线载波通信技术已经得到了广泛应用，然而，由于低压电力线信道中复杂的噪声环境、对通信信号的衰减问题以及阻抗特性的时变问题，严重制约了其可靠性和传输速度的提高。低压电力线的信道特征与低压电力线通信的调制方案、纠错编码以及网络拓扑选择有紧密的关系，但由于缺乏对低压电力线信道特性的深入探讨，导致在通信技术的选择过程中缺少足够的理论依据。本文针对低压电力线信道的噪声、信号衰减和阻抗时变等问题进行分析，，为进一步深入理解低压电力线信道特性提供必要的理论基础。首先对低压电力线的噪声特性进行分析。通过搭建低压电力线噪声测量电路，获取了低压电力线中的噪声情况。将电力线噪声分为背景噪声与脉冲噪声分别进行研究。对背景噪声利用自回归模型建模，分别利用奇异值分解法和Levinson-Durbin快速递推法对其参数进行求解，并比较两种方法的优劣；针对脉冲噪声模型提出将噪声特性分成群外特性与群内特性的两个层面上分别进行研究，并在时域与频域分别验证了模型的准确性，为建立高精度低压电力线信道噪声模型提供方法和依据。其次，以低压电力线噪声模型为基础，利用LabVIEW软件以及NI公司的PXI-5412板卡完成噪声发生器的设计，完成对实测噪声数据的重构，为研究低压电线的电磁兼容环境与高频信号在低压电力线上的传输特性提供实验基础。再次，对于低压电力线通信的信号衰减特性的研究。考虑到集肤效应与介电损耗对高频信号传输的影响，在均匀传输线理论的基础上，建立一种低压电力线的RLCG传输模型。模型参数的提取是通过对基本单元长度电力线的频率特性进行测量，并利用量子遗传算法进行辨识来完成的。实验与仿真结果表明，电力线RLCG模型在频域和时域上均能准确的反映电力线的高频传输特性及衰减特性。最后，对低压电力线网络阻抗时变性的研究，关注网络拓扑改变的实时监测问题。以RLCG模型与FSV方法为基础，提出利用随机脉冲噪声表征网络拓扑改变，经实验验证该方法可准确对随机脉冲噪声进行辨识，进而判断出网络拓扑结构的改变。准确检测网络拓扑的改变，并通知通信设备及时的调整通信方式和启用纠错技术，对提高低压电力线通信稳定性有重要意义。
[Abstract]:Low-voltage power line carrier communication technology has been widely used. However, due to the complex noise environment in the low-voltage power line channel, the attenuation of the communication signal and the time-varying impedance characteristics are discussed. The channel characteristics of low voltage power line are closely related to the modulation scheme, error correction coding and network topology selection of low voltage power line communication. However, due to the lack of in-depth discussion on the characteristics of low-voltage power line channels, there is a lack of sufficient theoretical basis in the selection of communication technology. This paper analyzes the noise, signal attenuation and impedance time-varying of low-voltage power line channels. It provides the necessary theoretical basis for further understanding the characteristics of low voltage power line channel. Firstly, the noise characteristics of low voltage power line are analyzed. The noise in low voltage power line is obtained. The power line noise is divided into background noise and pulse noise, and the background noise is modeled by using autoregressive model. The singular value decomposition (SVD) method and the Levinson-Durbin fast recursive method are used to solve the parameters, and the advantages and disadvantages of the two methods are compared. The accuracy of the model is verified in the time domain and the frequency domain respectively, which provides the method and basis for the establishment of the high-precision low-voltage power line channel noise model. Secondly, based on the low-voltage power line noise model, the noise generator is designed by using LabVIEW software and NI PXI-5412 card, and the reconstruction of the measured noise data is completed. It provides an experimental basis for studying the electromagnetic compatibility environment of low voltage power lines and the transmission characteristics of high frequency signals on low voltage power lines. Thirdly, the signal attenuation characteristics of low-voltage power line communication are studied. Considering the influence of skin effect and dielectric loss on high-frequency signal transmission, the uniform transmission line theory is used to study the signal attenuation characteristics of low-voltage power line communication. A RLCG transmission model of low voltage power line is established. The parameters of the model are extracted by measuring the frequency characteristics of the basic unit length power line and using quantum genetic algorithm to identify it. The experimental and simulation results show that, The power line RLCG model can accurately reflect the high frequency transmission and attenuation characteristics of the power line in both frequency domain and time domain. Finally, the study of time-varying impedance of low-voltage power line network is focused on the real-time monitoring of network topology change. Based on the RLCG model and FSV method, the stochastic impulse noise is proposed to represent the network topology change. It is proved by experiments that the method can accurately identify random impulse noise, and then judge the change of network topology, detect the change of network topology accurately, and notify the communication equipment to adjust the communication mode and use error correction technology in time. It is of great significance to improve the stability of low voltage power line communication.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM73

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