【正文】 1233210123模糊PID控制仿真模塊如下圖所示：圖47模糊PID控制仿真模塊模糊控制規(guī)則語言如下：(e is NB)and(ec is NB)then(kp is PB)(ki is NB)(kd is PS) (e is NB)and(ec is NM)then(kp is PB)(ki is NB)(kd is NS)(e is NB)and(ec is NS)then(kp is PM)(ki is NM)(kd is NB)(e is NB)and(ec is Z)then(kp is PM)(ki is NM)(kd is NB)(e is NB)and(ec is PS)then(kp is PS)(ki is NS)(kd is NB))(e is NB)and(ec is PM)then(kp is Z)(ki is Z)(kd is NM)(e is NB)and(ec is PB)then(kp is Z)(ki is Z)(kd is PS)(e is NM)and(ec is NB)then(kp is PB)(ki is NB)(kd is PS)(e is NM)and(ec is NM)then(kp is PB)(ki is NB)(kd is NS)(e is NM)and(ec is NS)then(kp is PM)(ki is NM)(kd is NB)(e is NM)and(ec is Z)then(kp is PS)(ki is NS)(kd is NM)(e is NM)and(ec is PS)then(kp is PS)(ki is NS)(kd is NM)(e is NM)and(ec is PM)then(kp is Z)(ki is Z)(kd is NS)(e is NM)and(ec is PB)then(kp is NS)(ki is Z)(kd is ZE)(e is NS)and(ec is NB)then(kp is PM)(ki is NB)(kd is ZE)(e is NS)and(ec is NM)then(kp is PM)(ki is NM)(kd is NS)(e is NS)and(ec is NS)then(kp is PM)(ki is NS)(kd is NM)(e is NS)and(ec is Z)then(kp is PS)(ki is NS)(kd is NM)(e is NS)and(ec is PS)then(kp is Z)(ki is Z)(kd is NS)(e is NS)and(ec is PM)then(kp is NS)(ki is PS)(kd is NS)(e is NS)and(ec is PB)then(kp is NS)(ki is PS)(kd is ZE)(e is ZE)and(ec is NB)then(kp is PM)(ki is NM)(kd is ZE)(e is ZE)and(ec is NM)then(kp is PM)(ki is NM)(kd is NS)(e is ZE)and(ec is NS)then(kp is PS)(ki is NS)(kd is NS)(e is ZE)and(ec is Z)then(kp is Z)(ki is Z)(kd is NS)(e is ZE)and(ec is PS)then(kp is NS)(ki is PS)(kd is NS)(e is ZE)and(ec is PM)then(kp is NM)(ki is PM)(kd is NS)(e is ZE)and(ec is PB)then(kp is NM)(ki is PM)(kd is ZE)(e is PS)and(ec is NB)then(kp is PS)(ki is NM)(kd is ZE)(e is PS)and(ec is NM)then(kp is PS)(ki is NS)(kd is ZE)(e is PS)and(ec is NS)then(kp is ZE)(ki is ZE)(kd is ZE)(e is PS)and(ec is Z)then(kp is NS)(ki is PS)(kd is ZE)(e is PS)and(ec is PS)then(kp is NS)(ki is PS)(kd is ZE)(e is PS)and(ec is PM)then(kp is NM)(ki is PM)(kd is ZE)(e is PS)and(ec is PB)then(kp is NM)(ki is PB)(kd is ZE)(e is PM)and(ec is NB)then(kp is PS)(ki is Z)(kd is PB)(e is PM)and(ec is NM)then(kp is ZE)(ki is Z)(kd is PS)(e is PM)and(ec is NS)then(kp is NS)(ki is PS)(kd is PS)(e is PM)and(ec is Z)then(kp is NM)(ki is PS)(kd is PS)(e is PM)and(ec is PS)then(kp is NM)(ki is PM)(kd is PS)(e is PM)and(ec is PM)then(kp is NM)(ki is PB)(kd is PS)(e is PM)and(ec is PB)then(kp is NB)(ki is PB)(kd is PB)(e is PB)and(ec is NB)then(kp is ZE)(ki is Z)(kd is PB)(e is PB)and(ec is NM)then(kp is ZE)(ki is Z)(kd is PM)(e is PB)and(ec is NS)then(kp is NM)(ki is PS)(kd is PM)(e is PB)and(ec is Z)then(kp is NM)(ki is PM)(kd is PM)(e is PB)and(ec is PS)then(kp is NM)(ki is PM)(kd is PS)(e is PB)and(ec is PM)then(kp is NB)(ki is PB)(kd is PS)(e is PB)and(ec is PB)then(kp is NB)(ki is PB)(kd is PB)模糊PID仿真圖像如圖48(af)所示：（a） 模糊變量仿真圖像(b)模糊變量仿真圖像(c)模糊變量仿真圖像(d)控制量U仿真圖像(e)水位偏差E變化仿真圖像(f)汽包液位模糊PID仿真圖像結論：通過對鍋爐水位分別采用模糊PID控制系統(tǒng)和單純采用PID控制的控制系統(tǒng)的兩種方案進行仿真對比驗證，從仿真圖像可以看出模糊PID有以下優(yōu)點：（1）汽包水位偏差E從震蕩到穩(wěn)定，響應時間短，水位偏差變化明顯變小。（2）模糊PID控制系統(tǒng)對影響鍋爐汽包水位各種干擾因素有較強的抑制能力。（3）當控制對象參數(shù)突然發(fā)生變化時，單純采用PID控制的系統(tǒng)超調量明顯變大，響應時間變長，系統(tǒng)振蕩加劇，控制效果不好。（4）模糊PID控制系統(tǒng)的超調量比較小，上升速度快，振蕩周期短。（5）當控制對象參數(shù)突然發(fā)生改變時，模糊PID控制系統(tǒng)對它的反應明顯很小、魯棒性好、適應力強，系統(tǒng)的靜態(tài)特性和動態(tài)特性都較好，對“虛假液位”的控制可以取得預期的控制效果。所以，模糊控制非常適合用于控制對象不確定的場合。第五章 結論及展望電廠鍋爐的水位調節(jié)過程需要建立精確的數(shù)學的模型，具有非線性、不穩(wěn)定性、時滯等特點。傳統(tǒng)的鍋爐汽包水位控制系統(tǒng)大都采用串級三沖量PID控制，其控制性能穩(wěn)定，能滿足但不能很好解決“虛假液位”問題。而模糊控制不要求知道被控對象的精確數(shù)學模型，只需要操作人員長期積累的實際操作經(jīng)驗知識及操作數(shù)據(jù)，所以人們想到把PID控制策略引入模糊控制中，構成FuzzyPID控制。考慮到鍋爐水位控制的復雜特性及模糊控制的特點，本文將模糊PID控制引入鍋爐汽包水位的控制中，取代傳統(tǒng)采用的PID的控制方式，以提高鍋爐水位的控制效果，尤其是針對“虛假水位”的抑制作了以下一些試探性工作：（1）對經(jīng)典的PID控制器特點做了歸納、總結，并結合鍋爐水位控制的特點，對汽包水位的模糊PID控制方式進行結構及性能上的分析和比較，并利用MATLAB中的Simulink仿真工具箱分別對設定值作用下對控制系統(tǒng)進行仿真。（2）模糊PID控制通過不斷檢測e及ec，根據(jù)事先確定的模糊規(guī)則，利用模糊推理的方法，通過不斷修改PID控制器參數(shù)，其具體過程是一個不斷尋優(yōu)過程，利用模糊控制器輸出調整PID控制器的三個參數(shù)。本文采用以水位偏差e及其變化ei作為輸入語句變量，以二維的模糊控制器對PID參數(shù)進行調整的控制方式進行了探討。仿真圖像結果表明控制效果較傳統(tǒng)的PID各項性能指標有一定的提高。（3）最后簡單介紹幾種由汽包水位測量方法及測量誤差帶來影響、及消除方法，通過現(xiàn)場實例解決了汽包水位測量不準的問題，減少了由于水位測量誤差給汽包水位帶來的不利影響，減少了影響鍋爐控制系統(tǒng)不利因素。隨著科技的飛速發(fā)展，鍋爐單機容量越來越大，但各種對鍋爐汽包水位影響的不確定因素也越來越多，本文只是在軟件上仿真了特定條件下的水位變化，提出用模糊PID解決汽包水位的“虛假液位”問題，但現(xiàn)場存在許多不確定因素，具體去應用還存在許多問題，有待我們繼續(xù)研究。參考文獻[1]孫優(yōu)賢，[M].[2]翁維勤，:化學工業(yè)出版社，[3]蔣慰孫，(第二版).北京:中國石化出版社，1988[4][M]. 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[6]孫秀全，[M].[7]孫優(yōu)賢，[M].[8]居滋培過程控制系統(tǒng)及其應用[M][9]何克忠。計算機控制系統(tǒng)[M][10]張亮明，夏桂娟編著工業(yè)鍋爐自動控制[M]中國建筑工業(yè)出版社1987[11]俞金壽編著工業(yè)過程先進控制[M]中國石化出版社2002[12]張良儀等編著工業(yè)鍋爐微機控制[M]上海交通大學出版社1991[13]居滋培主編過程控制系統(tǒng)及其應用[M]機械工業(yè)出版社2005[14]王芳，模糊自調整PID控制在鍋爐汽包水位控制中的應用[D],2006,山東大學碩士學位論文16[15]陳平,鍋爐汽包水位模糊PID控制的研究[D],，（4）：14。[16]樊國平，姚明海。模糊PID控制器的設計[J].制冷與空調2004年第四期[17][M].[18]王立新。編著模糊系統(tǒng)與模糊控制[M]清華大學出版社2003[19]黎兵，汽包鍋爐串級三沖量給水控制系統(tǒng)的MATLAB仿真，東北電力技術，2006(6):2122[20]吳曉莉等編著MATLAB輔助模糊系統(tǒng)設計[M]西安電子科技大學出版社2002[21]陳曉平等編著MATLAB及其在電路與控制理論中的應用[M]中國科學技術大學出版社2004[22]薛定宇編著控制系統(tǒng)計算機輔助設計MATLAB語言及其應用[M]清華大學出版社1996[23]郭妙娜,鍋爐汽包水位測量異常原因分析及改進[J]廣西電力2007年第六期[24]侯子良，劉吉川，侯云浩等．鍋爐汽包水位測量系統(tǒng)[M]．北京：中國電力出版社，2005．致謝首先，在本論文完成之際，我謹向我的導師陽武嬌致以最真摯的感謝和敬意!從課題方向的選擇、開題報告，到論文工作的理論分析，直至整個論文的撰寫、定稿，無不浸透著陽老師的汗水和心血。在此期間，陽老師給予我的無私幫助、悉心指點和諄諄教誨，不但使我把握了有關課題內容的前沿知識，而且有所創(chuàng)新。同時，陽老師嚴謹?shù)闹螌W態(tài)度、淵博的知識、平易近人的作風，都是我學習的榜樣。其次，要特別感謝高飛燕老師，李蘭君老師，感謝她們在四年大學學習中的悉心教導，另外，還要感謝王佳同學，當我論文寫作中遇到問題時，得到了他的熱情幫助，在此一并表示衷心的感謝。最后，我要感謝我的家人，他們的關心與支持，是我永遠的精神動力。再次向那些幫助過我人表示衷心的感謝!