Study On DMC For Crude Oil Tank's Temperature Control With Large Time-Lag Based On PLC

Crude oil tank's temperature is a complex controlled process because of its large time-lag and inertia, general PID control is difficult to obtain good control quality. Dynamic matrix control(DMC)is a optimum control algorithm and can be applied to controlled object with large time-lag, also it have advantages of rapid response, strong robust, these trait of DMC provide a chance for the high precision temperature control on crude oil tank. So this paper research and realize the DMC advance algorithm.Aimed at solve the problem of the temperature control of crude oil tank, this paper collect the fruit in control system simuation and identification, advance process control, automation. By building mathematic model and simuation combining the theory research to controlled object with large time-lag and the trait of crude oil tank, DMC strategy is put forward. We also summarize the rule between DMC parameter and control behave. Then we begin to write DMC programme based on s7-300PLC at process control experiment device on which exists a experiment object--electrical heating furnace that have the same characteristic with crude oil tank. After a great deal of effort is pain on programme debugging, the programme is successfully applied to control heating furnace's temperatureand a good control quality which is better than PID is acquired. Similarly, the same control result is acquired when we apply DMC's programme on crude oil tank's temperature controlAccording to both simulation and practice result, a conclusion can be obtain that the DMC strategy have the trait of strong robust and it is adapt to complex object with large time lag and inertia just like crude oil tank's temperature control. The conclusion show that DMC strategy is likely to be widely used in complex industry process with large time-lag.