| During the process of oil and gas exploration, staff underground need to monitor speed and torque of the downhole motor, deduced the running state of the motor. In this paper, a data transmission scheme is presented according to the power line carrier communication technology, to achieve long-distance transmission of downhole data using existing power line network.Firstly, the drilling information transmission technology was introduced and analyzed advantages and disadvantages of the wireless transmission and cable transmission when applied to the logging while drilling. Mud pulse method is widely used in the market for its low cost and high reliability; however cable transmission has better prospects for these methods can achieve a higher transmission rate and farther transmission distance.Secondly, the principle of power line communication was analyzed. Power lines are used to transmit energy, signal transmission quality will deteriorate when used to transmit signal. In order to improve the quality of power line communication, it is necessary to analyze the power line transmission characteristics to understand the characteristics of the power line input impedance, attenuation, time-varying, noise and other aspects to help design a reasonable system solution.Thirdly, the hardware circuit was designed according to the characteristic of power line. Binary frequency shift keying was used in system modulation and demodulation. AD9832 was used to modulate digital signal in the transmission end, and PLL chip NE564 was used to demodulate digital signal in the receiving end. Besides, amplifier, filter circuit and the coupling circuit was designed between the modulation circuit and demodulation circuit.Finally, a system test platform was set up and conducted power line carrier communication experiments to observe the signal transmission characteristics when permanent magnet synchronous motor under load of the communication system using test platform. |
PDF Full Text Request