油气管道内腐蚀外监测系统硬件电路设计

Hardware Circuit Design of External Monitor System of the Inner Corrosion for Oil and Gas Pipeline

目前,对于管道内部腐蚀的在线监测,最先进的商用系统是基于FSM(Field Signature Method)开发的,可以实现不需要在管道打洞,非破坏式的监测。但是现有设备通常采用直流电流源激励,存在信噪比低,易引起电火花,电缆较粗等诸多缺点。针对上述问题,本文采用交流激励电流源和锁相放大技术进行设计开发,对采集的微弱电压信号先进行前置放大,在达到足够的电平等级后,再推动锁相放大器进行锁相放大,去除所有不同频率的干扰。实验表明,本文所述的设计在信噪比、精度和稳定性上满足项目要求,可以很好地避免现有的基于直流激励技术的FSM设备所存在的问题。

Presently, for the pipeline internal corrosion monitoring, the most advanced commercial systems was developed based on field signature method（FSM）, can achieve nondestructive monitoring without punch holes in pipeline. However, the existing equipment usually use direct current stimulus, have many disadvantages, such as low signal-to-noise ratio, easy cause spark and cable coarser. Aiming at these problems, in this paper, ac excitation and lock-in amplifier were adopts to design the system circuit, firstly, preamplifier the weak voltage signal to achieve the electrical level grades of phase-locked loop, then using lock-in amplifier to remove all the other interference with different frequency. Experiments show that the design in this paper meet the project requirements on the accuracy and stability, and avoid the existing problems.