为什么需要MPC?
Single variable in & single variable out 单入单出
• Set up a target and control process variable to the target.
What would be a best SP is often unknown
PID
MPC
Multivariable in & multivariable out 多入多出
• Control strategy based on a cross correlated matrix
of key process variables
Feedback control 反馈控制
• The controller will take no action unless the errors show in PV
Predictive control 前馈控制
• Dynamic models developed through process step tests
• Future process behavior prediction and feed forward control
Indirect property variable control 间接质量控制
• Control property variables through temperature, pressure
or flow rate, etc.
Direct property variable control直接质量控制
• Property targets could be set and control directly
Poor control quality when there are large time
delays or complex dynamic interactions
难于处理大长滞后过程
PID set points are not necessarily optimal with
respect to plant wide objectives PID设定值基
于操作人员经验
Optimal PID targets are continuously calculated,
set, & modified PID
设定值根据模型连续优化计算和调整
Explicit dynamic models leverage computer
capabilities to calculate impact to the product
动态模型直接考虑过程动态