基于电力线工频通信的抽油机电机远程监测研究

Power Line TWACS-Based Remote Monitoring of Electric Machines for Pumping Units

针对油井位置分散、管理困难的现状,设计了基于电力线工频通信的抽油机电机远程监测系统。除了传统的电气参数外,采用Morlet复小波方法计算电机运行冲程内连续变化的电流基波幅值及相位,为抽油机本体的运行和故障判断提供信息。在监测数据传输方面,传统的工频通信方式以本地电压过零为基准,通过时域差分实现解调,在油田电网噪声干扰强,变电所与各配电变压器低压侧由于各种因素存在工频电压过零时差的环境中,难以进行同步检测,同时存在接收时域偏差而影响通信性能。为此,基于伪随机编码进行前导信息的调制,然后通过信号合成和时频分析确定数据编码的起始时刻和信号的调制时域,这样能够在油田电网恶劣的环境中进行同步检测,并且通过克服信号收发端电压相位差的影响而大大提高数据解调的质量。根据文中方法研制的远程监测系统已经在油田电网进行规模化试验运行,在低成本条件下实现了对抽油机电机的远程监测、管理。

In allusion to management difficulty of oil wells due to their dispersed locations,based on power line two-way automatic communication system（TWACS） a remote monitoring system of electric machines for oil wells is developed.In addition to traditional electrical parameters,the continually varying amplitude and phase of fundamental current within the stroke of electric machine are calculated by Morlet complex wavelet method to provide information of the operation and fault judgment for pumping units themselves.In view of strong noise interferences in oil field and time differences of zero-crossing points among low voltage sides of distribution transformers in substations caused by various factors it is difficult to perform synchronous monitoring and due to the deviation of receiving time-domain the performance of communication is affected,thus it is difficult to transmit monitoring data by traditional TWACS.For this reason,a new demodulation strategy is designed,in which the leading information is modulated based on pseudo-random code and then through signal synthesis and time-domain analysis the initial time of data coding and the modulation time-domain of signal are determined,thus the synchronous monitoring can be performed in the adverse circumstance of oil field distribution network and the quality of data demodulation can be evidently improved by overcoming the influence of phase differences of voltages at sending and receiving ends of the signal.The test run of the developed remote monitoring system is implemented in oil field distribution network in large scale,and the low-cost remote monitoring and management of electric machines for pumping units is realized.