Glass Melting Furnace Control Solution With PLC System

This task is to discuss and develop a control system consisting of seven glass melting furnace, the control proportion of this system is based on PLC (Programmable Logic Controller) and upper computer. The whole control system is asked for temperature control, the states storage of the glass melting furnace when it is working, and the control of the glass material added to and taken out from the melting furnace.This system adopts single PLC controller to dominate seven glass melting furnaces, so that the program frame is more complex than usual. In the coding process, we used hierarchical structure, though ladder diagrams, SFC ( Sequential Function Chart) program and FBD (Function Block Diagram) program to correspond different program, realized different function.The temperature control that is the core of the whole system adopts PID arithmetic. Because the melting furnaces are large-lag, un-liner system, it is hard to realize precision control with usual pattern. Usual PID controller pattern optimizes the parameters in certain temperature, in order to control the temperature accurately. In this case, the temperature is controlled under a mutative curve. The usual pattern does not suit for the pattern. So we used method of dynamic adjusting the parameters of PID arithmetic to improve the precision of temperature control. There are different parameters in different temperature, during this method the PID controller can work more effectively in a large temperature scale.Between the PLC control system and the upper computer, they communicate with each other by Ethernet agreement. But the different response time in them let the data storage more difficult. The PLC behaves as 'ms' and the upper computer behaves as's'. A buffer zone can work out this problem, let the PLC write to the buffer zone in little time interval, in larger time interval the upper compute can read the data in batches. So that the upper computer can reserve the high speed data in large space, it is helpful to improve the productivity. We also made some works on the safety of the system. Except adding high temperature alarming control module, we made the adding glass material in united control; avoid opening two furnaces in one time.