PPT《Decoupling Control Schemes of Multivariable Systems（多变...》

Decoupling Control Schemes of Multivariable Systems(多变量系统的解耦控制) Liankui DAI, Lei XIEInstitute of Industrial Control, Zhejiang University, Hangzhou, P.

R. China Tuning PID Controllers for 2*2 Interacting Systems If one loop is much faster than the other one, the fast loop is tuned first with the other loop in Manual. Then the slow loop is tuned with the faster loop in Automatic.If both loops are about the same speed of response, and one variable is more important to control than the other one, detune the less important loop by setting a small gain & a long reset time.Other cases…… When necessary to apply decoupling for a coupling process Strong interaction exists(存在强耦合): even for the best pairing option, one or more of the relative gains is far from unity, Both loops are about the same speed of response, and both CVs are of the same important(两回路动态特性接近,且两被控变量均同等重要). Problem Discussion For the controlled system, design your decoupling control systems and simulate your solution with SimuLink. If Initial states: Decoupler Design Decoupler(解耦器)Design PrincipleLinear Cascade Decoupler Based on Transfer Function Matrix G(s)Linear Feedforward Decoupler from G(s)Nonlinear Steady-state Cascade Decoupler Based on Basic Principles (基于过程机理的非线性稳态解耦器) Decoupler Design Principle Design decoupler to cancel the effects of the cross blocks, i. e., Block Diagram for a General 2*2 System with Decoupler #1 Decoupling Conditions ? Decoupler #1 for a General 2*2 System If About Decoupler #1 Problem: (1) initial MVs' value;

(2) "Man/Auto" mode switch;

(3) limit of MVs. Block Diagram for a 2*2 System with Feedforward Decoupler Feedforward Decoupler Design for a 2*2 System Dynamic decoupler: Steady-state decoupler: Feedforward Control & Feedforward Decoupler Existing Problems ? Nonlinear Steady-state Complete Decoupler (全解耦器) Design principle: introduce new variables v1, v2 to satisfy and Nonlinear Steady-state Triangular Decoupler (三角解耦) Design principle: introduce new variables v1, v2 to satisfy and Triangular Decoupler Design for a Blending Process Steady-state model: Let Triangular Decoupler for the Blending Process (cont.) Complete Decoupler Design for the Blending Process Steady-state model: Let Nonlinear Decoupler Design Example (cont.) Steady-state model: Nonlinear decoupler: Implementation of Nonlinear Decoupler Decoupler: Simulation of Nonlinear Decoupler for a Blending Process ( Please see …/Decoupling/NonlinearDecoupling.mdl ) Simulation Results of Nonlinear Decoupler Problem Discussion There are two branches in the following pump. Please design a control system to stabilize the flow in each branch, and reduce the coupling between the branches. Summary Concept of Relative GainsObtaining Process Gains and Relative Gain Matrix Rule of CVs and MVs Pairing Decoupling Design from Block DiagramsDecoupling Design from Basic Principles Next Topic: Boiler Control Schemes Process Diagram and Control Problems of Boiler (锅炉设备的生产流程与控制问题)Characteristic Analysis & Three-element Control for Drum Level (汽包水位特性分析与三冲量控制) Steam Temperature Control (蒸汽温度控制)详见《过程控制工程》12.4节(P.214)Problem Discussion (《过程控制工程》思考题与习题 12-3, P.223)