通常情況下，此過程的SMOCPro控制器將控制動作寫入兩個PID控制器的設(shè)定值（爐的TC和急冷的FC）瑰钮。為了使SMOCPro識別爐出口溫度變化以及反應(yīng)器瞬時效應(yīng)的變化邻辉，在SMOCPro模型中添加溫度控制PV作為中間變量。
Figure -3 SMOCPro control.
圖3： SMOCPro控制
該過程的模型為：
Figure -4 Reactor model with PID block.
圖4：反應(yīng)器模型PID功能塊
在這里爐出口溫度控制器是明確建模的毕箍。鑒于SMOCPro中的模型僅表示MVs對CVs的影響（針對預(yù)測目的）弛房，對于相同流程的等效模型是：
Figure -5 Equivalent Reactor model with closed loop dynamics.
圖5：閉環(huán)動態(tài)等效反應(yīng)器模型
爐溫的SP和PV的傳遞函數(shù)是溫度控制回路閉環(huán)動態(tài)行為。在ClosedDyn_FOT塊左上角的藍色三角形表示用于PID/串級回路動態(tài)模型的設(shè)置而柑。
在兩種情況下文捶，PID控制器將消化溫度PV的不可測量擾動荷逞。否則SMOCPro將通過改變PID設(shè)定點的方式嘗試消化干擾，因為這樣PID將補償溫度PV的變化粹排。這將導(dǎo)致PID設(shè)定點不必要的動作种远，以及整體質(zhì)量控制性能的惡化。
接下來的主題將說明在SMOCPro中如何實施這樣一個控制器設(shè)計恨搓≡捍伲控制器模型中基于PID模塊選擇的兩個選項都已顯示。只有進行設(shè)計相關(guān)點時才是詳細的斧抱。
兩個框架都有幾種常見的設(shè)計參數(shù)常拓。這些選項包括：
? 控制周期：60秒；
? 默認壓縮點辉浦；
? 操作變量權(quán)重弄抬；
名稱 阻尼系數(shù) 懲罰因子
FOT SP 0.1 0.901124
Quench F 0.1 0.400500
? 被控變量權(quán)重；
名稱 偏差 懲罰因子
Temperature 0.1 10
Quality 1 1
選項1
我們考慮的第一個選項是PID回路被明確建模的情況下宪郊。經(jīng)過模型編譯SMOCPro自動生成如下不可測量干擾：
這時候?qū)㈤_環(huán)閥位動態(tài)變化掂恕、PID設(shè)置準(zhǔn)確地與這些控制器實施的DCS對準(zhǔn)是沒有必要的。在SMOCPro中只有一種PID塊是可用的弛槐，因此在某些情況下在DCS和SMOCPro之間進行一些轉(zhuǎn)換是必要的懊亡；然而，SMOCPro的PID模塊必須在大多數(shù)情況下都滿足使用乎串。在本例中的開環(huán)傳遞函數(shù)是從其它例子拷貝的店枣，通過調(diào)諧P和I參數(shù)以獲得滿意的閉環(huán)響應(yīng)。
原文：
Normally, the control actions of a SMOCPro controller on this process are sent to the setpoints of the two PID controllers (TC at furnace and quench FC). To have SMOCPro recognize the variations in furnace outlet temperature and their transient effects on the reactor, include the temperature controller PV in the SMOCPro model as an intermediate variable.
The model for the process is:
Here the furnace outlet temperature controller was modeled explicitly. Because a model in SMOCPro only represents the effects of the MVs on the CVs (for prediction purposes), an equivalent model for the same process is:
The transfer function between the furnace temperature SP and its PV is the closed-loop dynamic behavior of the temperature controller loop. The Blue triangle in the top left corner of the ClosedDyn_FOT block denotes the setting for PID/Cascade loop dynamic model.
In both cases, the PID controller rejects the unmeasured disturbance on the temperature PV. Otherwise SMOCPro tries to reject the disturbances by changing the PID setpoint while the PID is compensating for the variations in temperature PV. This leads to unnecessary moves on the PID setpoint and a deterioration of the overall quality control performance.
The next topics illustrate how such a control design is implemented in SMOCPro. Two options are shown, based on the choice of PID model in the controller model. Only the relevant points in the design are detailed.
There are several design parameters common to the two frameworks. These options are:
? Control Period: 60 seconds
? Default compaction points.
? Manipulated Variable Weights
Name Damping factor Penalty
FOT SP 0.1 0.901124
Quench F 0.1 0.400500
? Controlled Variable Weights
Name Deviation Penalty
Temperature 0.1 10
Quality 1 1
Option 1
The first option we consider is the case when the PID loop is explicitly is modeled. After model compilation SMOCPro automatically generates the unmeasured disturbances as follows
It is not necessary that the open loop valve dynamics and the PID settings be aligned exactly with those of the controller implemented in the DCS. There is only one type of PID block available in SMOCPro and in some cases some conversions are necessary between the DCS and SMOCPro; however, the PID block within SMOCPro should satisfy most of the cases. In this example the open-loop transfer function was picked from another example and the P and I parameters are tuned to get a satisfactory closed-loop response.
2016.5.15
