The temperature control system of the reactor is PI control. Can you please teach me the principle of PI control?
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We have an imported high-pressure reactor, but the foreigner actually uses PI control instead of PID control. It is difficult to accurately control the temperature. It is necessary to set the heating power and p-band. These two parameters are difficult to adjust. Temperatures fluctuate greatly. I would like to ask that expert, can PI control be changed to PID control? Is it complicated or not? What is the price?
There are many methods for PID control and tuning in the forum, so you might as well search for them. PID is the abbreviation of proportion, integral and differential. Proportional adjustment function: It responds to the deviation of the system in proportion. Once a deviation occurs in the system, the proportional adjustment immediately produces an adjustment effect to reduce the deviation. The proportional effect is large, which can speed up adjustment and reduce errors, but * * A large proportion will reduce the stability of the system and even cause system instability. Integral adjustment effect: It is to eliminate the steady-state error of the system and improve the indifference. Because there is an error, the integral adjustment is carried out until there is no difference, the integral adjustment stops, and the integral adjustment output is a constant value. The strength of the integral effect depends on the integration time constant Ti. The smaller Ti, the stronger the integral effect. On the contrary, if Ti is large, the integral effect is weak. Adding integral adjustment can reduce the stability of the system and slow down the dynamic response. The integral effect is often combined with the other two regulation laws to form a PI regulator or PID regulator. differential adjustment: The differential effect reflects the rate of change of the system deviation signal and is foreseeable. It can predict the trend of deviation changes, so it can produce advanced control effects. Before the deviation is formed, it has been eliminated by the differential adjustment effect. Therefore, the dynamic performance of the system can be improved. When the differential time is appropriately selected, overshoot can be reduced and the adjustment time can be reduced. The differential effect amplifies noise interference, so excessive differential adjustment is detrimental to the system's anti-interference. In addition, the differential response is the rate of change, and when the input does not change, the output of the differential action is zero. The differential effect cannot be used alone and needs to be combined with the other two regulating laws to form a PD or PID controller.