Adaptive Multivariable MPC Controller PID Dynamics Removal
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current Model Predictive Control (MPC) systems in chemical and refinery processes face challenges in adapting to changes due to inherent correlations with PID dynamics, limiting their ability to operate independently and efficiently, especially when dealing with nonlinear processes.
Innovation Solution
A method is developed to remove PID dynamics from the MPC controller by interchanging final control element positions with PID controller set points using matrix row elimination, creating an open-loop finite impulse response model that allows for adaptive control without requiring new identification testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If standard identification tests are used to create MPC controllers, then the controller can be built with the same configuration of independent variables, but the PID dynamics become imbedded in the dynamic model creating variable correlation that prevents creating MPC controllers free of PID dynamics
Solution Approach 1:
The patent extracts PID dynamics from the process model by separating the PID controller transfer function from the plant model. This is achieved by taking the process model with PID controllers included and mathematically removing the PID portion, resulting in a process model that represents only the plant dynamics without the correlated PID behavior embedded in it.
2Productivity
If PID controller configuration is fixed during identification, then the dynamic model can be created, but the controller cannot be modified with new regulatory control configurations or tuning without conducting new identification testing
Solution Approach 1:
The patent segments the control system into separate components: the process model (plant dynamics), the PID controller model, and the MPC controller. By separating these elements, the process model can be used independently of any specific PID configuration, allowing different PID controllers to be designed and tuned without requiring re-identification of the underlying plant dynamics.
3Reliability
If MPC controller includes PID dynamics in the model, then the model accurately represents the controlled system behavior, but noise and correlation from PID loops respond to unmeasured disturbances and move controlled variables
Solution Approach 1:
The patent introduces an intermediate process model that serves as a mediator between the plant and the MPC controller. This intermediate model represents the plant dynamics without the PID controllers, acting as a clean interface that eliminates the harmful correlations and noise from PID loops while maintaining accurate representation of the controlled system behavior.
Data Source
AI summary
A method is disclosed for developing and using a high-speed adaptive multivariable controller by removing the dynamics of the PID controllers from a Model Predictive Controller that was developed using identification testing of a process. The resulting multivariable controller, based on final control elements as the manipulated variables is then used in a novel control adaptation with all of the PID controllers switched to manual.