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高压超临界萃取控制参数具有时变、非线性的特点,对其进行精确控制具有很大难度。PID控制广泛应用于工业过程控制,但常规PID控制器参数对运行工况的适应性差。模糊控制具有不依赖系统数学模型、调节速度快、鲁棒性好等优点,但稳态精度欠佳。将PID控制与模糊控制相结合,设计了模糊PID反馈控制器,形成了模糊PID复合控制方法。以软件代替硬件,利用某公司的S7-200 PLC编程语言STEP7编制了模糊PID控制程序,并结合组态王工控软件实现了高压超临界萃取装置的模糊PID控制。研究表明,模糊PID控制较小的超调量保证了超临界介质溶解度的稳定性,所建立的超临界萃取控制系统较强的抗干扰性、灵活性,保证了超临界萃取过程的稳定性和萃取效率。
The control parameters of high-pressure supercritical fluid extraction have the characteristics of time-varying and non-linearity, and it is very difficult to precisely control them. PID control is widely used in industrial process control, but conventional PID controller parameters poor adaptability to operating conditions. Fuzzy control does not rely on the system mathematical model, fast regulation, good robustness, etc., but the poor steady-state accuracy. Combining PID control and fuzzy control, a fuzzy PID feedback controller is designed and a fuzzy PID compound control method is formed. The software is used to replace the hardware. The fuzzy PID control program is compiled by STEP7, a company ’s S7-200 PLC programming language. Combined with the Kingview control software, the fuzzy PID control of the high pressure supercritical extraction unit is realized. The research shows that the smaller overshoot of fuzzy PID control can ensure the stability of the supercritical medium solubility. The established supercritical extraction control system has strong anti-interference and flexibility and ensures the stability of the supercritical extraction process. Extraction efficiency.