Feed Back Preformance-Process Control-Lecture Slides, Slides of Process Control

This lecture was delivered by Dr. Sakal Japendu for Process Control course at Ambedkar University, Delhi. It includes: Feedback, Performance, Evaluating, Control, Simulation, Frequency, Response, Dead, Time, Constant, Disturbance

Typology: Slides

2011/2012

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CHAPTER 13: FEEDBACK PERFORMANCE
When I complete this chapter, I want to be
able to do the following.
Apply two methods for evaluating control
performance: simulation and frequency
response
Apply general guidelines for the effect of
- feedback dead time
- disturbance time constant
- MV variability
- sensor and final element dynamics
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Download Feed Back Preformance-Process Control-Lecture Slides and more Slides Process Control in PDF only on Docsity!

CHAPTER 13: FEEDBACK PERFORMANCE

When I complete this chapter, I want to be

able to do the following.

Apply two methods for evaluating controlperformance: simulation and frequencyresponse

Apply general guidelines for the effect of- feedback dead time- disturbance time constant- MV variability- sensor and final element dynamics

Outline of the lesson.

Apply dynamic simulation

Apply frequency response to closed-loop performance

Guidelines for the effects of the process

Guidelines for the effects of the controlsystem

CHAPTER 13: FEEDBACK PERFORMANCE

CHAPTER 13: FEEDBACK PERFORMANCE

Evaluating control performance

During design, test possible plant changes, and developprinciples for guidelines- Dynamic simulation- Frequency Response

During plant operation- Fine tuning guidelines for set point- Complementary guideline for step disturbance- Monitor the performance

CHAPTER 13: FEEDBACK PERFORMANCE

Dynamic simulation solves the equations describing theprocess and controller - numerically because of complexityof systems. For example,

TC

v

v

  

  

=

=

=

=

=

=

=

t

m

SP

I

m

SP

c

valve

m

m

sensor

c

v

c

in

cout

cin

A

RT

E

rxn

p

P

A

RT

E

A

A

A

dt

T T T T T K

MV

MV

v

dt dv

T

T

dt

dT

P

C

v

aF

h

U

T

T

T

UA

C

e

Vk

H

T

T

C

F

dt

dT

C

V

C

e

Vk

C

C

F

dt

dC

V

0

6

0

0

0

0

0

1

'

)

(

)

(

)

(

)

(

)

(

))

(

(

)

(

)

(

)

(

max

.

/

/

τ τ

ρ

ρ

ρ

Many numerical

methods; Euler,

Runge-Kutta,

or other.

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0

50

100

150

0.9880.9860.9840.

IAE = 0.22254 ISE = 0.

Time (min)

XD (mol frac)

0

50

100

150

0.05 0.04 0.03 0.02 0.

IAE = 0.8863 ISE = 0.

Time (min)

XB (mol frac)

0

50

100

150

8550 8500 8450 8400 8350

Time (min)

R (mol/min)

0

50

100

150

1.38 1.36 1.

x 10

4

Time (min)

V (mol/min)

CHAPTER 13: FEEDBACK PERFORMANCE

Dynamic simulation is general and powerful.

F

R

F

V

x

B

x

D

AC

AC

DISTIL: Results of detailed, non-linear, tray-by-tray dynamic model with PID feedbackcontrollers. Simulation in MATLAB.

xF

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PRESENT VALUES

1) Total simulation time

100.

2) Time step for simulation

0.

3) Set point change

0.

4) Disturbance change

0.

5) Process reaction curve MV input

0.

6) Select continuous/digital controller, currently continuous

(Controller executed every simulation time step)

7) Execute dynamic simulation8) Return to main menu

0

20

40

60

80

100

120

0

0.4 0.3 0.2 0.

S-LOOP plots deviation variables (IAE = 7.5136)

Time

Controlled Variable

0

20

40

60

80

100

120

-10 -15 -20 -

0

Time

Manipulated Variable

)

1

2

)(

1

)(

1

(

)

1

(

3

2

2 3

2

1

s

s

s

s

s

s

e

K

lead

p

ξτ

τ

τ

τ

τ

θ

 



s

T

s

T

K

d

I

c

1

1

SP(s)

MV(s)

D(s)

CV(s)

Disturbance model

Process feedback modelPID controller model

Controlledvariable

Setpoint

Disturbance

Manipulatedvariable

)

1

2

)(

1

)(

1

(

)

1

(

3

2

2

3

2

1

_

s

s

s

s

s

s

e

K

d

d

d

d

d

d

lead

d

d

τ

ξ

τ

τ

τ

τ

θ

CHAPTER 13: FEEDBACK PERFORMANCE

Dynamic simulation is general and powerful.

Simulation of single-loop linear systems is easily achieved using theS_LOOP program in MATLAB. Cases are possible for systems withand without control for step inputs

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CHAPTER 13: FEEDBACK PERFORMANCE

Frequency Response: determines the response of systemsvariables to a sine input.

Professors want to ruin the semester for students

Perfect sine disturbances occur frequently inplants

We want another case for dynamic simulation

We use sine to characterize time-varying inputs,especially disturbances

We can learn useful generalizations about controlperformance

Why do we study frequency response?

No!

No!

No! Yes!

Yes!

Are you sure

of this answer?

CHAPTER 13: FEEDBACK PERFORMANCE

Frequency Response : Sine in

sine out without control

Process dynamics for

disturbance T

in

to T

K

d

θθθθ

τ τ

τ τ

min

Process dynamics for

MV v

2

to T

K

p

θθθθ

ττττ

= 5 min

Three cases withamplitude 1 K anddifferent T

in

sine

periods, P.

A

P = 5000 minP = 50 minP = 0.05 min

For each case,what is the outputamplitude?

Let’s do a

thought

experiment,

without

calculating!

B

C

T

v

v

T

in

CHAPTER 13: FEEDBACK PERFORMANCE

Frequency Response : Sine in

sine out without control

Process dynamics for disturbance T

in

to T

K

d

θθθθ

ττττ

= 5 min

Process dynamics for MV v

2

to T

K

p

θθθθ

= 5 min ;

τ τ

τ τ

= 5 min

T

v

v

T

in

B

FREQUENCY =0.12629 rad/time & AMP RATIO =1.

0

100

200

300

400

-0.

0

1

CV

0

100

200

300

400

-0.

0

1

Disturb., magnitude = 1

P = 50 min

CHAPTER 13: FEEDBACK PERFORMANCE

Frequency Response : Sine in

sine out without control

Process dynamics for disturbance T

in

to T

K

d

θθθθ

ττττ

= 5 min

Process dynamics for MV

v

2

to T

K

p

θθθθ

= 5 min ;

ττττ

= 5 min

T

v

v

T

in

C

P = .05 min

FREQUENCY =126.2939 rad/time & AMP RATIO =0.

0

-0.

0

1

CV

0

-0.

0

1

Disturb., magnitude = 1

CHAPTER 13: FEEDBACK PERFORMANCE

Frequency Response : Sine in

sine out with control

Process dynamics for

disturbance T

in

to T

K

d

θ θ

θ θ

= 0 min ;

ττττ

5 min

Process dynamics for

MV

v

2

to T

K

p

θθθθ

ττττ

= 5 min

Three cases withamplitude 1 K anddifferent T

in

sine

periods, P.

A

P = 5000 minP = 5 minP = 0.005 min

For each case,what is the outputamplitude?

Let’s do a

thought

experiment,

without

calculating!

B

C

TC v

v

T

in

CHAPTER 13: FEEDBACK PERFORMANCE

Frequency Response : Sine in

sine out with control

Process dynamics for disturbance T

in

to T

K

d

θθθθ

= 0 min ;

τ τ

τ τ

= 5 min

Process dynamics for MV

v

2

to T

K

p

θθθθ

τ τ

τ τ

= 5 min

TC v

v

T

in

FREQUENCY =0.0012496 rad/time & AMP RATIO =0.

0

1

2

3

4

5

x 10

4

-0.

0

1

CV

0

1

2

3

4

5

x 10

4

-0.

0

1

Disturb., magnitude = 1

A

P = 5000 min

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CHAPTER 13: FEEDBACK PERFORMANCE

Frequency Response : Sine in

sine out with control

Process dynamics for disturbance T

in

to T

K

d

θθθθ

= 0 min ;

τ τ

τ τ

= 5 min

Process dynamics for MV

v

2

to T

K

p

θθθθ

ττττ

= 5 min

TC v

v

T

in

B

P = 50 min

FREQUENCY =0.12629 rad/time & AMP RATIO =1.

0

100

200

300

400

-0.

0

1

CV

0

100

200

300

400

-0.

0

1

Disturb., magnitude = 1

Frequency Response : Sine in

sine out with control

Summarize the results for many frequencies in a Bode Plot

10

10

10

10

0

10

1

10

2

10

3

10

10

10

10

0

10

1

Frequency, w (rad/time)

Amplitude Ratio, |CV| / |D|

A

B

C

Please

discuss