Model Predictive Control for small applications for small applications

về MPC

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Model Predictive Control for small applications

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Advantages of Model Predictive Control

– Automatically compensate for process

interaction, measurable load disturbances and constraints using MPC function block.

– Difficult process dynamics may be effectively

addressed e.g deadtime dominant

– Allow production to be increased by

automatically adjusting throughput to maintain

a process at its input operating constraint.

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Multi-variable Control Made Easy

Example: Control loop with one disturbance and one constraint

MPC Traditional Approach

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Saving by Operating Closer to Product Specification or Operating Limit

$$ Savings

Limit or Spec Target Setpoint

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Throughput May be Operating at Process Input Limit or Operating Constraint

Time Throughput

Production Increase $$ Throughput

at limit Operator Setpoint

MPC

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MPC

Temperature

Process (1X1)

MPC - Addressing Difficult Dynamics

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MPC -Addressing Difficult Dynamics

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MPC -Addressing Difficult Dynamics

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Automated process testing to identify

the process model

Automated process testing to identify

the process model

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Step Response Model

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Verification of identified model

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Testing of control using simulated environment

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Example Operator interface to MPC

Future Values

of control

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MPC Process

(2X1)

Measured Disturbance

MPC Replacement for PID with Feedforward

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MPC Replacement for PID with Feedforward

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MPC Process

(1X2)

Unmeasured Disturbance

Constraint

MPC Replacement for PID Overrride

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MPC Replacement for PID Overrride

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MPC Process

(2X2)

Addressing Process Interaction

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MPC

Process (1X1)

Unmeasured Disturbance

PID

MPC

RCAS_IN RCAS_OUT

Layering MPC on Existing Strategy

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Exposing RCAS_IN & RCAS_OUT

Right click on the control or AO

block to expose the RCAS_IN as

an Input parameter and RCAS_OUT as an Output parameter.

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Layering MPC on an Existing Strategy

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Example - Long-tube Rising Film

Evaporator

Example - Long-tube Rising Film

Evaporator

Æ Feed enters the bottom

of the heating tubes and

as it heats, steam begins

to form

Æ Usually there must be a

rather high temperature difference between the heating and boiling sides

Æ Extensively used for

food, pharmaceutical, and many industrial applications

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Evaporator Products Solids Control With Temperature and pressure Constraints

Traditional Strategy - 3 PID’s

and Control Selector Blocks

Predict Strategy - 1 MPC Block

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Installation Experience

Æ 5 Evaporator units commissioned to-date using

DeltaV Predict

Æ Much faster to config! Much easier to Tune No

de-coupling of loops, 13 minutes and your done!

Æ MPC is easier to manipulate from startup SFC's

This is a no-brainer, manipulating the mode of

one block would always be easier than four.

Æ Simple and easy to use!!!!!!!!! No grey matter

needed!

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Installation Experience

Æ Operators love the MPC Operator Display

Evaporator Graphics are less cluttered with one

MPC, than 3 PID dynamo's

Æ MPC operator interface is much more simple and

easier to use On the older plants with overide

control the operators never know which of the 3

loops is controlling the final control element They

never know if they are constraining the plant via

temp or heater pressure and therefore sometimes

run the process at lower throughput rates than they need to $$$$$$$.

Tiêu đề	Model predictive control for small applications
Trường học	Fisher-Rosemount Systems, Inc.
Thể loại	bài tập tốt nghiệp
Năm xuất bản	2006

Định dạng
Số trang	27
Dung lượng	0,92 MB