【摘要】：液位控制作為過程控制的一個重要組成部分,在石油、化工、冶金等工業(yè)流程自動化領(lǐng)域占有重要地位。液位控制系統(tǒng)有非線性、不確定性的特點,研究和設(shè)計使液位系統(tǒng)具有良好性能的先進(jìn)控制方案和控制算法一直是學(xué)者和機(jī)構(gòu)關(guān)注的焦點。本文基于儲聯(lián)罐液位系統(tǒng)的數(shù)學(xué)模型,設(shè)計了液位系統(tǒng)的PID、模糊和線性二次型調(diào)節(jié)器(linear quadratic regulator—LQR)控制算法,并在此基礎(chǔ)上,設(shè)計了液位系統(tǒng)的切換控制算法。首先,建立液位系統(tǒng)的數(shù)學(xué)模型。根據(jù)液位系統(tǒng)的文獻(xiàn)資料、研究報告,建立基于實驗平臺的液位系統(tǒng)數(shù)學(xué)模型。為方便液位系統(tǒng)中控制器的設(shè)計,采用泰勒公式將非線性模型展開,給出液位系統(tǒng)的線性模型。然后,圍繞建立的系統(tǒng)的線性模型,提出了PID控制算法,模糊控制算法和LQR控制算法。根據(jù)各控制算法的原理,分別設(shè)計PID控制器的比例、積分、微分控制參數(shù),模糊控制器的模糊控制規(guī)則、隸屬度函數(shù)和解模糊方法以及LQR控制器的狀態(tài)加權(quán)矩陣和控制加權(quán)矩陣,給出液位系統(tǒng)的各控制算法的控制器結(jié)構(gòu),仿真結(jié)果表明所述的三種控制方法均能使液位系統(tǒng)取得令人較為滿意的控制效果,但LQR控制算法對液位系統(tǒng)具有最佳的穩(wěn)定性。最后,在對比分析所提出的三種控制算法的基礎(chǔ)上,針對液位系統(tǒng)在液位初始上升階段模型不確定問題并使系統(tǒng)具有良好的穩(wěn)定性,提出了液位系統(tǒng)的模糊和LQR切換控制方案。利用“分解—合成”的多模型建模策略,將液位系統(tǒng)的工作范圍劃分為多個工作小區(qū)間,建立系統(tǒng)的多模型集合,基于系統(tǒng)的模型集合設(shè)計系統(tǒng)的控制器集合,并根據(jù)系統(tǒng)液位反饋值設(shè)計模糊、LQR控制切換準(zhǔn)則。為保證系統(tǒng)在液位穩(wěn)定的情況下實現(xiàn)控制器之間的平穩(wěn)切換,避免出現(xiàn)液位大幅度波動現(xiàn)象,設(shè)計了模糊和LQR的加權(quán)控制。仿真結(jié)果說明提出的控制方案對液位系統(tǒng)具有良好穩(wěn)定性。
[Abstract]:As an important part of process control, liquid level control plays an important role in petroleum, chemical, metallurgical and other industrial process automation fields. Liquid level control system has the characteristics of nonlinearity and uncertainty. The research and design of advanced control schemes and control algorithms that make the liquid level control system have good performance has been the focus of attention of scholars and institutions. Based on the mathematical model of the liquid level system of the storage tank, this paper designs the PID, fuzzy and linear quadratic regulator (linear quadratic regulator-LQR control algorithm of the liquid level system, and on this basis, designs the switching control algorithm of the liquid level system. Firstly, the mathematical model of liquid level system is established. According to the literature and report of the liquid level system, the mathematical model of the liquid level system based on the experimental platform is established. In order to facilitate the design of controller in liquid level system, the nonlinear model is expanded by Taylor formula, and the linear model of liquid level system is given. Then, the PID control algorithm, fuzzy control algorithm and LQR control algorithm are proposed around the linear model of the system. According to the principle of each control algorithm, the proportion, integral and differential control parameters of PID controller and the fuzzy control rules of fuzzy controller are designed respectively. The membership function and fuzzy method, the state weighting matrix and control weighting matrix of LQR controller are given, and the controller structure of each control algorithm of liquid level system is given. The simulation results show that the three control methods mentioned above can make the liquid level system achieve a satisfactory control effect, but the LQR control algorithm has the best stability to the liquid level system. Finally, on the basis of comparing and analyzing the three control algorithms proposed, a fuzzy and LQR switching control scheme for the liquid level system is proposed in view of the uncertainty of the model of the liquid level system in the initial rising stage of the liquid level and the good stability of the system. By using the multi-model modeling strategy of "decomposition-synthesis", the working range of the liquid level system is divided into several working intervals, and the multi-model set of the system is established, and the controller set of the system is designed based on the model set of the system. Fuzzy and LQR control switching criterion are designed according to the feedback value of system liquid level. In order to ensure the smooth switching between controllers and avoid the phenomenon of large fluctuation of liquid level, fuzzy and LQR weighted control are designed. The simulation results show that the proposed control scheme has good stability to the liquid level system.
【學(xué)位授予單位】：濟(jì)南大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：TP273

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