案例5：加熱器傳遞平衡應(yīng)用的液位控制
(\Program Files\ShellGlobalSolutions\PCTP\Tutorial\SMOCPro\Tutorial5_PassBalancer.wsp)
這個(gè)例子是從原油精餾裝置的加熱器傳遞平衡控制應(yīng)用中提取的。這項(xiàng)工作的目的是為了向用戶說明在競爭性斜坡和穩(wěn)定受控變量的存在下CV優(yōu)先級的影響。
過程模型
SMOCPro模型包含了8個(gè)可允許流股作為操作變量（MVs）去達(dá)到控制目標(biāo)。控制模型具有17個(gè)過程輸出變量（POVs）并且編譯為周期1.0min。請參閱workspace以了解關(guān)于模型的詳細(xì)信息。
控制器設(shè)計(jì)
SMOCPro應(yīng)用程序有以下4個(gè)控制目標(biāo)：
? 控制塔液位到設(shè)定點(diǎn)（Level）；
? 平衡加熱器出口溫度(TDZPass)；
? 平衡每對旁路流股共享的共同出口溫度(DF)；
? 保持管表層溫度低于高限(Skin Temperatures)。
該控制應(yīng)用包含了一個(gè)單獨(dú)的子控制器。如下所示，所有的模型POVs都被定義為被控變量（CVs）。
控制器的整定權(quán)重是：
最后，默認(rèn)壓縮點(diǎn)被用來搭建控制器。
該控制器沒有經(jīng)濟(jì)函數(shù)和靜態(tài)約束。
仿真
在本例中我們考慮到的方案都包含在workspace中。案例之間的唯一差別是液位（Level）CV的優(yōu)先級。下表高亮了所考慮的不同的優(yōu)先級。
| Baseline_Level_Prio_50 | Level_Prio_30 | Level_Prio_20 |
|---|---|---|
| CV (類型)Priority(優(yōu)先級) | CV (類型) Priority(優(yōu)先級) | CV (類型) Priority(優(yōu)先級) |
| Skin Temperatures（表層溫度） 1 | Skin Temperatures（表層溫度） 1 | Skin Temperatures（表層溫度） 1 |
| DFij 10 | DFij 10 | DFij 10 |
| TDZPassi 30 | TDZPassi 30 | TDZPassi 30 |
| Level（液位） 50 | Level（液位） 30 | Level（液位） 20 |
所有的POV和MV變量初始條件，CV期望的Setrange值，以及MV操作條件如Maximum Move Rate和SP高低限等都存儲(chǔ)在相應(yīng)的仿真場景中（例：“Baseline_Level_Prio_50,” “Level_Prio_30” 和 “Level_Prio_20”。所有3個(gè)場景中Level和Skin Temperature等CVs都起始于各自的setranges內(nèi)沿。剩下的CVs(增量流股“DFij” 和增量溫度“TDZPassi”)都起始于setranges外部?？刂破髌鹗紩r(shí)處于“Standby”模式，且在第5步切換到“Control”模式。在第80,90,100和110步我們分別向Delta Temperatures引入不可測干擾（UNM）信號(hào)TDZPassA, TDZPassC, TDZPassE和TDZPassG。最后，在第300步我們將Level的設(shè)定點(diǎn)由50提高到60。
原文：
**Case 5: Heater Pass-Balancer Application with Level Control **
(\Program Files\ShellGlobalSolutions\PCTP\Tutorial\SMOCPro\Tutorial5_PassBalancer.wsp)
This example has been extracted from a heater pass balancer control application for a crude distilling unit. The goal of this exercise is to illustrate to the user the effect of CV priority in the presence of competing ramp and stable controlled variables.
**Process Model **
The SMOCPro model contains 8 flows available as manipulated variables (MVs) to meet the control objectives. The control model has 17 process output variables (POVs) and is compiled with a period of 1.0 minute. Please refer to the workspace for complete details about the model.
**Controller Design **
The SMOCPro application has the following four control objectives:
? Control the column level to setpoint (Level),
? Balance the heater pass outlet temperatures (TDZPass),
? Balance the pass flows in each pair that share a common outlet temperature (DF), and
? Maintain tube skin temperatures below high limits (Skin Temperatures).
The control application contains a single sub-controller. All of the model POVs are defined as controlled variables (CVs) as shown below.
The controller tuning weights are:
Lastly, default compaction points are used to build the controller.
The controller has neither Economic Functions nor Static Constraints.
**Simulation **
The scenarios that we consider in this example are all contained in the workspace. The only difference between the scenarios is the Level CV priority. The table below highlights the different priorities under consideration.
| Baseline_Level_Prio_50 | Level_Prio_30 | Level_Prio_20 |
|---|---|---|
| CV (type) Priority | CV (type) Priority | CV (type) Priority |
| Skin Temperatures 1 | Skin Temperatures 1 | Skin Temperatures 1 |
| DFij 10 | DFij 10 | DFij 10 |
| TDZPassi 30 | TDZPassi 30 | TDZPassi 30 |
| Level 50 | Level 30 | Level 20 |
Initial conditions for all the POV and MV variables, desired Setrange values for the CVs as well as MV operating conditions such as Maximum Move Rate and SP High and Low limits are stored in the corresponding Simulation Scenario (i.e. “Baseline_Level_Prio_50,” “Level_Prio_30” and “Level_Prio_20”). For all three scenarios the Level along with the Skin Temperature CVs all start within their respective setranges. The rest of the CVs (delta flows “DFij” and delta temperatures “TDZPassi”) start outside their setranges. The controller starts in “Standby” mode and is switched to “Control” at step 5. At steps 80, 90, 100 and 110 we introduce ramp disturbances into the Delta Temperatures’ unmeasured disturbance (UNM) signals TDZPassA, TDZPassC, TDZPassE and TDZPassG, respectively. Lastly, at step 300 we raise the setpoint on the Level from 50 to 60.
2016.6.5
