Development Of A Experimental System For The Pressure Control Of A Large Pressure Cylinder

Pressure cylinder usually was used to simulate under-water pressure environment.This article takes a75m3pressure cylinder as controlled object, developing a pressurecontrol system of a large pressure cylinder. A method which controls the influx and effluxof liquid volume in the large cylinder is adopted to realize the internal pressure control ofthis75m3pressure cylinder with high precision. This article has mainly completed thefollowing work：1.Based on the function requirements of this pressure cylinder auto-control system，this article accomplished the design of the whole system, which is constituted by highpressure water pipeline g system, electrical drive system and control system.2.This article set up a control platform, which consisted of industrial controlcomputer and Programmable logic controller（PLC）, and also exploited the PLC controlprogram and upper computer monitoring software. The duty of PLC is state parameteracquisition,control law operation and control signal output,while the upper computertakes charge of both the condition monitoring of the whole control system and providinga friendly human-machine interactive interface.The Ethernet was used to realize real-timecommunication between upper and lower computers. Because of high reliability of PLC,the pressure control system could maintain normal operation even if IPC is abnormal.3. In order to resolve the hysteresis effect of flow control valve, this article came upwith the following compensation schemes. Fistly, the Knocker’s stiction compensationwas introduced in the control system to overcome the problem of system oscillation,meanwhile,in order to avoid aggressive stem movement, the compensation actionthresholds was proposed, which was determinated by the variation of the controlleroutputs. Also, friction compensation controller was designed in this paper, whichincreased compensation value based on valve movement direction so that response speedwas improved. Besides, Zero drift has been corrected for high sensor measurementprecision. 4. The pressure control system was modified and tested on spot. The experimentresults showed that the system could meet the design requirements fantastically. Also, thestiction compensation introduced overcame the problem of system oscillation, made thesystem meet the fast response and high precision requirements simultaneously, thus, theaccurate control of the static pressure maintenance and dynamic pressure tracking cametrue.At present, the system has been completed and put into use.