【作者】 卢文冰；

【导师】 罗应立； 孙凤杰；

【作者基本信息】 华北电力大学 ， 电力系统及其自动化， 2011， 博士

【摘要】 数据传输系统是实现电机群远程监控的重要环节,以电力线为媒介传输电机监控数据具有设备成本低、安装方便、没有通信服务费用等优势,但电力线不是专门的通信线路,配电网中的各种负载运行时会产生各种干扰噪声,对电力线通信信号的解调非常不利。本文根据电机监控管理的地域范围,采用跨越变压器台区的工频电力通信和低压电力线载波通信方式来传输电机监控数据,在研究这两种电力线通信关键技术的基础上,研制了能够适应工业配电网信道环境的电力线数据传输系统为电机远程监控提供信息通道,并进行了规模化的现场实验运行。论文的主要工作及成果如下：1)针对地域分布较广的电机设备远程监测需求,设计了基于电力线工频通信方式的数据传输系统,通过低频畸变信号穿越变压器实现远距离通信,无须在高压线路加装耦合设备,并且根据工业配电网信道环境结合电机远程监测特点,设计了信号检测方案。2)提出了基于伪随机编码和时频分析来实现的工频通信系统同步检测方法,通过伪随机编码进行前导信息的调制与接收合成,然后根据工频通信信号的频域特征,基于多窗口短时傅里叶变换分析合成信号的幅频参数确定编码起始工频周期,基于短时傅里叶变换结合魏格纳分布分析同步合成信号的幅频参数随时间分布情况来确定信号的调制时域。3)在工频通信信号的调制时域得到确定的基础上,采用自适应干扰抵消技术等方法来抑制调制时域的电网干扰,然后基于互相关或小波分析等技术进行数据解调,这样能够通过克服收发端电压相位差的影响而提高通信性能。4)采用多载波扩频方式来实现电机监测信息在低压电力线传输,针对低压电力线信道时变性大且存在随机强窄带干扰的特点,通过信号解调中所获得的信道状况来自动调节载波通信的频率及速度,同时信道状况参数还为载波中继接力通信的路径优化提供关键依据。在上述研究基础上,研制了基于电力线通信的电机远程监控数据传输系统；跨变压器台区工频通信信号的检测以MCU和16位A/D转换器为核心进行,低压电力线载波信号的调制解调以AVR单片机和模拟比较器为平台实现。通过工业配电网的现场规模化实验运行证明,该系统能够可靠地跨变压器远距离传输电机远程监测数据,并且能够在低压电力线可靠传输监控数据。更多还原

【Abstract】 Data transmission system is an important part of the motor group remote monitoring.The system which transmit motor monitoring data using the power line has advantages such as low-cost equipment, easy installation, no cost of communication services and so on. But power line is not dedicated communication line, so there will be varieties of loads which produce interference noise run in the distribution network, and it’s a harmful factor in the PLC signal demodulation.In this thesis, according to the geographical scope of the motor control management,the TWACS which can across the transformer area and the low voltage power line carrier-current communication is used to transmit motor monitoring information. Based on the research of the key technology of the two kinds of power lines of communication,a power line data transmission system which can adapt to industrial distribution network channel environment is developed to provide information channel for the motor remote monitoring. And the field experiment operation is taken in scale.The main work and achievements are as follows:(1) According to the demand of motor remote monitoring which has a wide regional distribution.Based on TWACS, a data transmission system is designed to realize the remote communication by the low frequency distortion signal which can through transformer.There is no need of adding coupling equipment in high voltage line.A signal detection scheme is designed according to the industrial distribution network channel environment and the characteristics of the motor remote monitoring.(2) The power frequency communication synchronization method is put forward based on pseudo-random code and time-frequency analysis. The modulation, synthesis and receiving of the information is carried through the pseudo-random code. According to the frequency domain features of the power frequency communication signal,the industrial frequency cycle of the coding is determine by the amplitude-frequency parameters provided by multitaper short-time Fourier transform analysis. The modulation time domain of the signal is confirmed through the amplitude-frequency parameters provided by STFT and Wagener distribution which is used to analysis synchronous synthesis signal.(3) Based on the confirming of the modulation time-domain, the grid interference in modulation time-domain is inhibited by the use of adaptive interference offset technology.The demodulation is carried out by skills such as cross-correlation or wavelet analysis,and the influence of phase difference of the voltage can be overcomed so that the communication performance can be improved.(4) The transmission of the motor monitoring information in low voltage power line is realized by the way of Multi-Carrier spread spectrum. According to the dynamicity of the low voltage power lines channel and the existing of random strong-narrow band interference. The carrier communication frequency and speed is automatic controlled by the channel condition obtained in signal demodulation. Channel condition parameters can also provide key basis for the path optimization of the carrier relay communications.Based on the research above,the motor remote monitoring data transmission system based on power line communication is developed. MCU and16-bit A/D converter as the core of the detection of the power frequency communication signal cross transformer area. The modulation and demodulation of the low voltage power line carrier signal is realized on a platform consist of AVR SCM and analog comparator. Through the massive field experiment in industrial distribution network,it is proved that the motor remote monitoring data can reliably across transformer and the transmission of the monitoring data in low voltage power lines is reliable.更多还原