干擾抑制
現(xiàn)在我們把注意力轉(zhuǎn)向控制器整定室抽。在這個例子中惧财，目標(biāo)是調(diào)諧控制器魯棒性以抵消不可測干擾對液位的影響。此外崔慧，我們向仿真中引入噪聲并與先前討論的選型作比較拂蝎。
過程模型
在控制器模型中，存在著兩個可能的干擾來源：Inlet Flow（進(jìn)料流量）是不可測量干擾惶室，Measurement Noise（可測量噪聲）將被用于直接向液位測量中注入干擾。通常情況下玄货，以下兩種類型的干擾將輸入到系統(tǒng)：
? 類白噪聲干擾可能是由于出料流量執(zhí)行器的噪聲（難以預(yù)測的）皇钞；
? 階梯狀干擾，可能表示注入相關(guān)的進(jìn)料流量（可能停留片刻）松捉。
對某個控制器夹界，從長遠(yuǎn)來看最好忽視第一種類型，并要盡量保持對第二種類型的可預(yù)見性隘世。這項考慮被嵌入在一個叫Impulse Factor（脈沖因子可柿，數(shù)值在0.0~1.0范圍內(nèi)）的調(diào)諧參數(shù)中鸠踪。這個參數(shù)代表了在POV估算中當(dāng)前預(yù)測誤差可能在控制時域中消失的部分所占的百分比。
控制器設(shè)計
控制器搭建時將儲罐液位定義為CV复斥。此外营密，如下圖所示，我們將Vessel Level SR（儲罐液位SR）定義為一個Elaborated（復(fù)雜的） CV目锭。這個額外的CV允許我們將儲罐液位的Setrange（設(shè)定范圍）定義一個較高的優(yōu)先級评汰，而為設(shè)定點定義較低的優(yōu)先級。
接下來痢虹，我們制定了下列move suppression（動作抑制）和被控變量權(quán)重被去。
最后，我們對快速控制動作感興趣奖唯，因此如下圖所示惨缆，默認(rèn)的MV時域100 × dT將被修改為5 × dT。記住進(jìn)行這項修改時要使用Calculator（計算器）功能丰捷。
仿真
在這個仿真中我們將關(guān)注先前討論的兩種類型的干擾坯墨，隨機(jī)噪聲和斜坡干擾將被注入儲罐中。我們用兩種方法實現(xiàn)這些干擾瓢阴，以展示給用戶向不可測擾動變量(UNM)和測量變量注入干擾的差異畅蹂。
我們要運(yùn)行的第一組仿真，是將干擾直接注入到Inlet Flow（進(jìn)料流量：不可測干擾）變量中荣恐。對這種情況液斜，General仿真情景選項卡包含下列設(shè)置：
原文：
Disturbance Rejection
Now we turn our attention to controller tuning. In this example, the goal is to tune the controller for robustness against unmeasured disturbance rejections on the Level. In addition, we compare the previously discussed options of introducing noise into the simulation.
Process Model
In the controller model, there are two possible sources for disturbances: the Inlet Flow is an unmeasured disturbance and the Measurement Noise will be used to inject disturbances directly into the Level measurement. Typically, two types of disturbances enter the system:
? A white noise-like disturbance possibly due to noise on the Outlet Flow actuator (Hardly predictable), or
? A step-like disturbance that may represent coherent Inlet Flow injection (Likely to stay for a while).
From a controller point of view, it may be best to disregard the first type in the long run and to try to keep a certain predictability of the second type. This consideration is embedded in the tuning parameter called the Impulse Factor (with values between 0.0 and 1.0). This parameter represents the percentage of the current prediction error in the POV estimation that is likely to vanish along the control horizon.
Controller Design
The controller is build with the Vessel Level defined as a CV. In addition, we define Vessel Level SR as an Elaborated CV as shown below. This extra CV allows us to define a high priority Setrange with a low priority setpoint for the Vessel Level.
Next, we specify the following move suppression and controlled variable weights.
Lastly, we are interested in fast control action therefore the default MV horizon of 100 × dT gets modified to 5 × dT as shown below. Remember to use the Calculator feature when making this change.
Simulation
We now present simulations where the two types of disturbances previously discussed, namely random noise and a ramp disturbance, are injected into the vessel. We implement these disturbances in two ways to show the user the difference between injecting the disturbances into the unmeasured disturbance variable (UNM) and into the measurement directly.
The first set of simulations that we run are with the disturbances being injected directly into the Inlet Flow (unmeasured disturbance) variable. For this case the General simulation scenario tab contains the following settings:
2016.5.22
