Engineering Realization And Debug Of Control System Of4400/400Paper Machine Air-cushion Headbox

In the paper-making industry, the Air-cushioned headbox is key junctionfor connecting delivering and forming parts of paper-making machine. In theheadbox control system, frequency changer changes the rotate speed of rootsblower to control the flow of air. Frequency changer also change rotate speed offan pump to control the flow of paper pulp. Add the pressure of air and pressureof paper pulp is the total pressures value of air-cushioned. This value decidesthe spouting velocity.In this paper, based on the evection of Hebei province, was designed afuzzy decoupling controller. Fuzzy control is a branch of intelligent control.Using the fuzzy control method can get the good control result in the situationthat the structure of controlled plant will be change. In this condition, it is hardto build the mathematical model of controlled plant. Based on the experience ofoperator, fuzzy controller will be export the result when the control system isreceiving the signal of input. It is necessary that use the decoupling control inthe system that controlled quantity and outcome exist the coupled relation in thecontrolled plant，for example, the air-cushioned control system. Using the fuzzycontrol and diagonal decoupling method, designed the Fuzzy decouplingcontroller and got a better result by MATLAB. This paper summaries theprinciple and usage of hardware in this project, such as, upper computer ofDELL, SIEMENS200PLC，ABB VFD，VACON VFD，Delta VFD. On bothsides of headbox, pressure transducer and liquid level transducer were beinstalled, they change the physical quantity to the current signals which be usedto constitute the feedback control. To reduce the electromagnetic interference(EMI), power-supply filter and signal isolator were be installed inthe control cabinet. STEP7Micro/WIN is used to programme for SIEMENS200PLC. Access software as a bridge for linking the upper computer and200PLC. Their communication protocol is RS485.In the end, the questions and methods were be summaried, such as how totest the stability of control system, matters need attention of install transmitter,deal with the EMI, how to set the parameter of VFD, how to use the softwareabout this project, and the procedure of debugging, etc. These projectexperiences will help the people who debughs the control system of single foldthe nets of air-cushion headbox.