It has been widely accepted that applying the traditional control method is difficult to achieve precise temperature control of the evaporator because the evaporator temperature has nonlinear, time-varying characteristics with a significant lag. Based on the evaporator production process analysis, an evaporator temperature control method based on the cascade fuzzy adaptive proportional-integral-differential (PID) is proposed here, which combines the fuzzy control theory with the cascade PID control theory to set up a Continuous Function Charts (CFC) configuration of fuzzy adaptive PID control for the main loop and the secondary loop. A real-time self-adapting amendment of PID parameters in the main loop and the secondary loop during the evaporator temperature control can be realized using this control strategy. The experimental results with the SMPT-1000 simulation equipment and Siemens PCS7 process control system show that after the real-time self-adapting amendment of PID parameters, the computed new proportional parameter can successfully accelerate the response speed of the system, the calculated new integral parameter can efficiently reduce the deviation of the system, and the deduced new differential parameter can wisely play an essential role in the anticipatory control. The corresponding experimental results demonstrated that the adjustment time of temperature response could be shortened by one-half, and the maximum deviation could be reduced by more than four-fifths. Additionally, the adjustment time of the temperature rise load could be shrunk by more than three-fifths, and the maximum deviation could be decreased by more than four-fifths. Moreover, the recovery time for the superheated steam perturbation could be narrowed by more than one-half, and the deviation of minimum and maximum temperature could be condensed by more than one-tenth. It is noteworthy that compared with the traditional cascade PID control method, the cascade fuzzy self-adaptive PID control strategy proposed here has the notable advantages of short regulation time, slight overshoot, and good robustness, which can overcome the shortcomings of the traditional cascade PID control method and provide an effective way and mathematical models to solve the problem of accurate temperature control in the evaporator. Therefore, the control strategy developed here has a particular significance in ensuring the smooth operation of the evaporator.
SUN Jun
,
ZHANG Dian
,
HUANG Qing-Shan
,
TIAN Liang
,
CHANG Tian-Qi
,
LIU Qi
. Design of temperature control system for evaporator based on cascade fuzzy self-adaptive PID method[J]. The Chinese Journal of Process Engineering, 2023
, 23(9)
: 1290
-1299
.
DOI: 10.12034/j.issn.1009-606X.222320