【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(jié)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(jìn)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(yīng)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(qiáng)的抑制能力。（3）當(dāng)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(diào)量明顯變大，響應(yīng)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(diào)量比較小，上升速度快，振蕩周期短。（5）當(dāng)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(yīng)明顯很小、魯棒性好、適應(yīng)力強(qiáng)，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(yù)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(jié)論及展望電廠鍋爐的水位調(diào)節(jié)過程需要建立精確的數(shù)學(xué)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(xué)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(gòu)成FuzzyPID控制?？紤]到鍋爐水位控制的復(fù)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(jié)，并結(jié)合鍋爐水位控制的特點，對汽包水位的模糊PID控制方式進(jìn)行結(jié)構(gòu)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(shè)定值作用下對控制系統(tǒng)進(jìn)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(diào)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(jìn)行調(diào)整的控制方式進(jìn)行了探討。仿真圖像結(jié)果表明控制效果較傳統(tǒng)的PID各項性能指標(biāo)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(zhǔn)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(jī)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(yīng)用還存在許多問題，有待我們繼續(xù)研究。參考文獻(xiàn)[1]孫優(yōu)賢，[M].[2]翁維勤，:化學(xué)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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