Constant Potential Control And Digitization Based On Pulse Current Cathodic Protecton System

With the development of industry,the electrochemical corrosion of metal is more and more serious.Pulsed current cathodic protection technology has many advantages over ordinary DC cathodic protection technology,but its has many parameters and its difficult to achieve constant potential control due to there is phenomenon of protection potential response hysteresis and overshoot.In this paper,the constant potential control system of metal under the action of pulse current and its digital interface technology are studied.In the study,the mechanism and selection of protection parameters of pulsed current cathodic protection,the evaluation theory of cathodic protection effect and the digital method of pulsed current cathodic protection system are studied at first.In the laboratory,the performance of the program-controlled power supply which affects the pulse current cathodic protection is tested,and the linear relationship between the output voltage of the power supply and the set value is obtained.Then,the ruthenium-iridium titanium alloy reference electrode was calibrated by a double reference system under the same conditions.The results showed that the difference between the negative potential measured by ruthenium-iridium titanium alloy reference electrode and the negative potential of saturated calomel electrode was about 590 mV.Second on the influencing factors of constant potential control(medium resistivity),medium temperature and medium flow experiment and study,it is concluded that the role of law,again to pulse current constant potential control of cathode protection system control strategy research,on the software control method USES the classical PID control algorithm,using computer simulation,the results show that the potential can be controlled in the range of demand;On the hardware control,a dual-chip control structure is designed.The main chip is controlled by STM32F103,and the sub-chip is controlled by ATMEGA16 L.The current acquisition circuit and protection potential acquisition circuit based on ATMEGA16 L chip were designed,and the temperature acquisition circuit,dielectric resistivity acquisition circuit,dielectric velocity acquisition circuit and other auxiliary circuits were designed based on STM32F103 control chip.In terms of digital interface,STM32F103 based rs232/485 interface circuit,Ethernet interface circuit and USB interface circuit are designed.Finally,the technique of constant potential control and digital technology of the studied pulsed current cathodic protection system are applied to the inner wall of the gathering and transportation pipeline of the oilfield station.The installation methods of flexible anode,dotted anode and reference electrode were designed according to the direction,layout and the requirement of pulsed current cathodic protection on the inner wall of the pipeline,and the digital monitoring was installed and adjusted.The final results show that the measured potential of each reference electrode is constant within a reasonable range,and the requirement of pulsed current cathodic protection on the inner wall of gathering and transporting pipeline is fulfilled.