Analysis of Stiction Effect on the Dynamics of Compressor ...
Compensation of Control valve stiction
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Transcript of Compensation of Control valve stiction
![Page 1: Compensation of Control valve stiction](https://reader031.fdocuments.in/reader031/viewer/2022021920/58d1eddc1a28ab51448b5e03/html5/thumbnails/1.jpg)
Compensation of Control
valve stiction
Supervised by
Dr. Dr. M.A.A. Shoukat Choudhury
Professor
Department of Chemical Engineering
BUET
Prepared by
Md. Habibur Rahman
Std. ID- 0902016
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Outline of presentation
Background Of Study
Objective Of Study
Available Compensation methods
Development of a new stiction compensation model
Comparison of Different Models
Experimental evaluation
Conclusions And Recommendations
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Background of Study
Automation of modern plants
Control loop performance
Stiction as a process nonlinearity
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Stiction in
Control valve
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Stiction in Control valve(cont’d)
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Objectives
The overall objectives of our study are:
Study different Compensation techniques
Development of a new technique
Evaluation of the performance of new method
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Available Compensation Methods
Knocker method
CR method
Two move method
Adaptive control method
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Proposed Model
Controlle
rValve
inputProcess
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Simulation Diagram
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Proposed Model Mechanism
1800 1900 2000 2100 2200 2300 2400-4
-3
-2
-1
0
1
2
3
4
Time(s)
Co
mp
ensa
tor
Ou
tpu
tC
on
tro
ller
Ou
tpu
tS
tem
Po
siti
on
Set
po
int
Compensator Output
Set Point
Stem Position
Controller Output
A B
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Comparison of different models
Models
Knocker model
CR model
Adaptive model
Proposed model
Parameters
Process variable
Stem Position
Impact on valve reversals
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0 200 400 600 800 1000 1200 1400 1600-8
-6
-4
-2
0
2
4
6
8
PV Vs. Time
Time(s)
PV
Comparison(cont’d)
Knocker Model
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Comparison(cont’d)
CR Model
0 200 400 600 800 1000 1200 1400 1600-8
-6
-4
-2
0
2
4
6
8
PV Vs. Time
Time(s)
PV
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0 200 400 600 800 1000 1200 1400 1600-8
-6
-4
-2
0
2
4
6
8
PV Vs. Time
Time(s)
PV
Comparison(cont’d)
Adaptive Model
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Comparison(cont’d)
0 200 400 600 800 1000 1200 1400 1600-8
-6
-4
-2
0
2
4
6
8PV Vs. Time
Time(s)
PV
Proposed Model
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Parameter Knocker CR Adaptive Proposed
Initial
variance(PV)
6.00 6.00 6.00 6.00
Final
Variance(PV)
1.148 1.074 0.32 0.27
Variance Ratio 0.1913 0.1790 0.0533 0.045
%Reduction in
Variance
80.86 82.1 94.66 95.5
Analysis of Process variable varianceComparison(cont’d)
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Comparison(cont’d)
Analysis of Valve reversals
11 11
18
6
0
2
4
6
8
10
12
14
16
18
20
Knocker CR Adaptive Proposed
No
of
Val
ve
rev
ersa
ls
Model
No of Valve reversals vs. Process model
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Comparison(cont’d)
Analysis of Stem Position of valve
0.571
0.535
0.321
0.214
0
0.1
0.2
0.3
0.4
0.5
0.6
Knocker CR Adaptive Proposed
Stem
po
siti
on
Am
plit
ud
e R
atio
Model
Stem position Amplitude Ratio vs.Model
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Comparison(cont’d)
Summary of comparison Analysis
The Proposed model is beneficial over other models in
the following manners:
Reduction of oscillations in process
Reduction of valve movement
Good set point tracking and disturbance rejection.
Avoidance of excessive control action.
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Experimental Evaluation
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0 1000 2000 3000 4000 5000 6000-5
0
5
10
15
20
25
30
35
40
45
Time(s)
Pro
cess
Vari
ab
le(P
V)
Process Variable(PV) vs. Time
Experimental Evaluation(cont’d)
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Experimental Evaluation(cont’d)
143
23
0
20
40
60
80
100
120
140
160
PV variance(Initial) PV variance(Final)
Pro
cess
Var
iable
var
iance
Condition
Process Variable varance
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Conclusions
A new model for stiction compensation is developed
Comparison of different models are done
Performance test of the proposed model is evaluated
experimentally
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Experimental work to compare with other models
Correlation of model parameter with different
processes
Recommendations
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Any Question?