【正文】 I 摘 要 汽包水位是影響余熱鍋爐安全運行的一個重要參數(shù)。汽包水位過高或過低的后果都是非常嚴重的。因此對汽包水位必須進行嚴格控制。單片機技術的快速 發(fā)展使得單片機廣泛應用于過程控制領域并極大地提高了控制 性能。 本設計從分析影響汽包水位的各種因數(shù)出發(fā)，提出了采用汽包水位三沖量控制系統(tǒng)方案。按照工程整定的方法，進行了 PID 參數(shù)整定，并以 MATLAB 為仿真平臺進行仿真，仿真結果表明此控制系統(tǒng)具 有較高的調節(jié)質量和調節(jié)精度，能夠維持汽包水位的穩(wěn)定。根據(jù)控制要求和所設計的控制方案進行了 系統(tǒng)的硬件設計，利用了單片機的編程實現(xiàn) 控制算法并進行系統(tǒng)的軟件設計，最終完成單片機在余熱鍋爐汽包水位控制系統(tǒng)中的應用。 關鍵詞 ：汽包水位 三沖量控制 單片機 PID 控制 II ABSTRACT Drum water level is an important para meter influencing the safe operation of the surplus energy boiler. The consequences are very serious w hen the w ater level is too high or too low. So the drum water level must be strictly controlled. The rapid development of SCM technology makes it widely used in control field and it improves the performance of control greatly. According to the influence of various factors on the drum water level, this design adopts the three impulse control system scheme of drum level. According to the method of engineering tuning, the design adopts the tuning of PID parameters and uses MATLAB as the simulation platfor m. The simulation results show that this control system has high quality regulation and it can maintain the stability of the drum level. According to the control requirements and the desi gn scheme of the control system, the hardware design w as carried out. The softw are design of the system uses SCM programming control. Finally, we can finish that the drum water level of the surplus energy boiler is controlled based on SCM. Keywords: water level of the steam drum three impulse control SCM PID control I 目 錄 摘 要 .................................................................................................... I ABSTRACT ..........................................................................................II 第 1 章 緒論 ......................................................................................... 1 本設計研究的目的和意義 .......................................................... 1 國內外發(fā)展情況 ......................................................................... 3 第 2 章 余熱鍋爐汽包水位的設計 ...................................................... 5 汽包水位控制系統(tǒng)的動態(tài)特性分析 .......................................... 5 保持汽包正常水位的意義 .................................................. 5 被控參數(shù)與控制變量選擇 .................................................. 6 在給水流量擾動下的動態(tài)特性 ........................................... 8 在蒸汽流量擾動下的動態(tài)特性 ........................................... 9 控制系統(tǒng)的方案 ........................................................................11 單沖量控制系統(tǒng) ................................................................ 12 雙 沖量控制系統(tǒng) ................................................................ 13 三沖量控制系統(tǒng) ................................................................ 15 方案選擇 ........................................................................... 16 建立數(shù)學模型 ........................................................................... 16 汽包水位控制系統(tǒng)的數(shù)學模型 ......................................... 17 測量變送環(huán)節(jié)的傳遞函數(shù) ................................................ 18 執(zhí)行機構的傳遞函數(shù) ........................................................ 19 儀表的選擇與各變送器轉換系數(shù)的確定 ................................. 19 流量變送器轉換系數(shù)的計算 ............................................. 19 給水調節(jié)閥轉換系數(shù)的計算 ............................................. 20 液位變送器轉換系數(shù)的計算 ............................................. 20 第 3 章 硬件電路設計 ........................................................................ 21 A/D 轉換電路 ............................................................................ 22 I/V 變換電路 ............................................................................. 23 II D/A 轉換電路 ............................................................................ 24 DAC0832 的簡介 ................................................................ 25 AT89C51 與 DAC0832 的接口電路設計 ............................ 26 V/I 變換電路 ............................................................................. 27 AT89C51 對 LCD 的接口電路 ................................................... 28 聲光報警電路 ........................................................................... 29 AT89C51 的最小系統(tǒng) ................................................................ 30 復位電路 ........................................................................... 31 時鐘電路 ........................................................................... 32 電源電路 ........................................................................... 33 上位機與 AT89C51 的通信 ...................................................... 34 第 4 章 軟件設計 ............................................................................... 36 程序流程設計 ........................................................................... 36 系統(tǒng)主程序流程圖 ............................................................ 36 系統(tǒng)的初始 化子程序 ........................................................ 37 A/D 轉換檢測子程序 ......................................................... 38 增量型 PID 控制算法子程序 ............................................ 42 D/A 轉換監(jiān)控 子程序 ......................................................... 46 報警子程序流程圖 ............................................................ 46 第 5 章 PID 參數(shù)整定及仿真 ............................................................ 48 PID 控制器參數(shù)整定 ................................................................. 48 系統(tǒng)仿真分析 ........................................................................... 51 總 結 ................................................................................................. 54 致 謝 ................................................................................................. 55 參考文獻 ............................................................................................. 56 附錄 1: VI 電路仿真圖 ....................................