PID控制器在抗干扰模式下由PID回路产生不可测干扰。FOT (PV)对FOT(Error)的阶跃响应如下图所示：
值得一提的是，PID抗干扰通过动态链接的方法传递到温度和质量。我们现在开始搭建基于这些响应的控制器。进行的仿真具有下列特征：
1、 在第5步时质量的设定点从80改到85；
2、 系统中引入了两种类型的干扰。首先是炉温（在第70步时使用FOT(Error)注入的5摄氏度斜坡），其次是反应器温度（在第120步时使用温度(Error)注入的10摄氏度斜坡）。
3、 反应器温度被保持在最高温度615℃以下。炉的PV不控制，但仅把它当做一个中间变量。
4、 温度上限比质量的设定点具有更高的优先级（温度的优先级是1，质量的是10）。
该方案（信息）表视图如下：
General选项：
Sub-controller选项:
下图显示了该例子的仿真结果。
对质量的设定点变化是不可行的（黄色的质量最小值单元格），因为温度到了上限（绿色的温度最大值单元格）。
很显然在第70步，SMOCPro很难通过操作FOT SP（和Quench）补偿FOT的扰动。这是因为根据PID控制器，其预测的质量依然处于稳定的状态。
在第120步，SMOCPro预测到质量将偏离标准，于是开始操作FOT SP和Quench（激冷气）以消除干扰。
方案2
控制器模型中不包括PID配置；但为PID控制器闭环动态选择了一个PID/串级回路设定。
添加了不可测扰动的模型如下所示：
Figure -6 Reactor model with unmeasured disturbances
图6：添加了不可测扰动的反应器模型
和选项1一样，PID控制器在抗干扰模式下由PID/串级回路产生不可测干扰动态。如下图所示为模型对不可测干扰的阶跃响应。
和前面一样，PID抗干扰通过动态链接的方法传递到温度和质量。此建模方法搭建控制器的性能与第一个案例是类似的。
原文：
The unmeasured disturbance generated for the PID loop models the disturbance rejection pattern of the PID controller. The response of the FOT (PV) to a step response in the FOT (Error) is:
It is worth noting that the PID disturbance rejection spreads to the Temperature and the Quality by means of the dynamic links. We now proceed to build a controller based on these responses. The simulation is performed with the following characteristics:
- A setpoint change for the quality is forced at step 5 from 80 to 85.
- Two types of disturbances are introduced into the system. First on the temperature of the furnace (5-degree ramp injected using FOT (Error) at step 70) and then on the reactor temperature (10-degree ramp injected using Temperature (Error) at step 120)
- The reactor Temperature is kept under a maximum of 615 degrees C. The furnace PV is not controlled but used only as an intermediate variable.
- The Temperature upper limit has a higher ranking than the Quality setpoint. (Priority 1 for Temperature and, 10 for Quality).
The scenario (information) table views are:
General tab:
Sub-controller tab:
The figure below shows the simulation results for this study.
The setpoint change on the Quality is infeasible (Minimum cell of Quality in yellow) because the Temperature reaches its upper limit (Maximum cell of Temperature in Green).
It is clear that SMOCPro hardly manipulates the FOT SP (and Quench) to compensate the disturbance on FOT at step 70. This is because it can predict the quality remains on specification at steady state due to the PID controller.
At step 120, SMOCPro predicts the quality off specification and manipulates the FOT SP and Quench to reject the disturbance.
Option 2
The PID configuration is not included in controller model; but a PID/Cascade loop setting is chosen for the closed loop dynamic of the PID controller.
The model with the unmeasured disturbances looks like:
As with Option 1, the unmeasured disturbance dynamics generated for the PID/Cascade loop model the disturbance rejection pattern of the PID controller. This is illustrated in the model responses to steps in the unmeasured disturbances as shown below.
As before, the PID disturbance rejection spreads to the Temperature and the Quality using the dynamic links. The performance of the controller built with this modeling approach is similar to that seen with the first option.
2016.5.17
