Research On Key Technology Of Stray Current Detector For Oil And Gas Pipelines

Oil and gas pipelines are known as the "lifeline project" of China’s energy.Stray current is one of the important factors that cause external corrosion and affect the safe operation of oil and gas pipelines.In recent years,the parallel or intersection of buried steel pipelines,electrified railways,high-voltage transmission lines and other interference sources has increased,forming "common corridor",and the harm of stray current has become increasingly serious.Aiming at the problems of single function,poor anti-interference ability and low intelligence of domestic stray current detection equipment at present,this thesis proposes a stray current detector for oil and gas pipelines,which improves the localization of foreign SCM detection technology and integrates various detection technologies.Focusing on the key technologies of stray current detectors,this thesis mainly completes the following four aspects:(1)Derive the detection principle of the stray current detector for oil and gas pipelines.The magnetic field generated by the stray current on pipelines is qualitatively analyzed by electromagnetic field theory and Maxwell software modeling,and a scheme of sensor array composed of six high-precision three-component magnetic sensors is proposed,and on this basis the mathematical model of stray current magnetic field value and current value is established.(2)Complete the hardware function design of the stray current detector for oil and gas pipelines.Firstly,the sensor selection design is carried out,and the F902high-precision three-axis fluxgate sensor is selected as the magnetic sensor,and the portable copper sulfate reference electrode is selected as the potential sensor;secondly,the modular hardware circuit design is carried out,including signal conditioning module,signal acquisition module,main control module,storage module,remote communication module,LCD display module,test block power interruption method control module,power supply and its conversion module.Finally,the appearance structure design of stray current detector is carried out.(3)Complete the software function design of the stray current detector for oil and gas pipelines.The software design of the lower computer is based on the MDK5 development environment,using the STM32 function library for modular programming development;the software design of the upper computer is based on Lab VIEW and Qt to build potential signal and magnetic field signal upper computer platform respectively;the remote cloud platform is based on B/S architecture and adopts the development method of front-end and back-end separation.(4)Build an experimental prototype of stray current detector for oil and gas pipelines,and complete prototype testing and experiments.The results show that the prototype developed in this thesis can detect several stray current evaluation indexes,among which,the measurement error of pipe-to-soil potential,AC interference voltage and soil surface potential gradient is less than 0.1%,which meets the standard requirements;the detection accuracy is about 35 m A@1m,that is,the minimum stray current that can be detected at a burial depth of 1m is about 35 m A.