Process Exam 1-1
pdf
keyboard_arrow_up
School
University of Houston *
*We aren’t endorsed by this school
Course
3132
Subject
Aerospace Engineering
Date
Apr 3, 2024
Type
Pages
10
Uploaded by CountCapybaraMaster28
True/ False: 1.
A PID controller with a derivative on measurement feature will experience a spike due to a set point change 2.
In general, the tuning parameter for set point tracking is more conservative due to a smaller closed-loop time constant. 3.
A feedforward controller is realizable if the disturbance dead time is shorter than the process dead time. 4.
In a cascade controller, the outer loop is tuned for the set point tracking. 5.
One of the reasons to adopt a combined FF/FB controller is to take care of unmeasured disturbance. 6.
In a bumpless transfer from the manual mode to auto mode, you set the correct process variable value a the immediate set point (before ramping) and the current valve output as the bias. 7.
An override controller is one type of PID controller that is used to compete with another PID controller used for normal operations. NOT
False
PID
controller
with
derivative
on
measurement
feature
is
design
to
have
sudden
changes
leg
:
setpoint
change)
:
prevent
spike
in
control
signal
-
False
tuning
parameter
is
more
aggressive
because
smaller
loop
allows
the
system
to
respond
faster
to
set
point
changes
-
>
quicker
convergence
and
tighter
tracking
.
-
LONGER
!
'
False
False
outer
loop
:
provide
fast
disturbance
rejection
inner
loop
:
tunned
for
setpoint
tracking
True
FF
:
directly
compensate
disturbance
FB
:
Correct
any
remaining
error
to
ensure
accurate
control
-
False
current
controller
al
output
↓
NOT
Falze
Wrong
!
override
controller
is
used
to
temporarily
take
control
of
a
system
when
necessary
(eg
:
emergency)
8.
A reverse acting controller has a negative KC. 9.
An interacting PID controller is a PI controller in series with a PD controller 10.
In gerneral, the tuning parameter set for set point tracking is more conservative due to a smaller closed-loop time constant. 11.
A regression has an explained variance of 60 out of a total variance corrected for the mean of 100, then the R2 is 0.4 12.
A PID controller with a derivative (on measurement) feature will experience a spike due to a set point change 13.
The performance of a PID controller with filter can make the controller output more sluggish and smoother compared to a regular PID controller. 14.
In a cascade controller, the inner loop is tuned for disturbance rejection 15.
In the primary loop process modeling of cascade control of the jacketed reactor (WS11). The manipulated variable is the set point of the secondary controller (jacket temperature control) set point. False
TITIVE
True
more
aggressive
False
aiming
for
faster
response
and
tighter
tracking
False
R
=
=
60/100
=
0
6
↓
False
NOT
True
adding
a
filter
will
cause
rapid
changes
in
the
control
signal
making
the
output
response
slower
but
smoother
False
outer
loop
:
provide
fast
disturbance
rejection
inner
loop
:
tunned
for
setpoint
tracking
True
16.
In ITAE, the errors occur at the later part of the response period will contribute more to the penalty criteria 17.
One of the reasons to adopt a combined feedforward/feedback controller is to take care of unmeasured disturbances. 18.
A feed-forward controller is realizable if the disturbance dead time is shorter than the process dead time 19.
A PI controller is often used to avoid excessive valve movements due to noises and to eliminate offset. 20.
A PI controller does not have a fixed bias. 21.
In a bumpless transfer from the manual mode to the auto mode, you set the current process variable value as the immediate set point (before ramping) and the current valve output as the bias. 22.
A bias in a P-only control is the controller output (for valve opening) that will control the process variable as the immediate set point (before ramping) and the current valve output as the bias. -
>
Integral
Time
Absolute
Error
are
contranted
more
d
True
heavily
in
the
penalty
criteria
True
FF
:
directly
compensate
disturbance
FB
:
Correct
any
remaining
error
to
ensure
accurate
control
men
False
LONGER
!
True
PI
controller
help
smooth
out
control
action
by
integrating
past
errors
,
reducing
impact
of
noise
and
eliminating
steady-state
offset
which
can
prevent
excessive
value
moment
True
Pl
controller
adjust
based
on
the
accumulated
error
over
time
--
False
current
↓
-
controller
output
True
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help
23.
A reverse acting controller has a negative K Control Station: 1.
What is the bias of a P-Only controller? 2.
What is the bias in a PI controller? 3.
What is an open loop? 4.
What is “proportional band”? 5.
What are the major concerns of applying the derivative actions in the presence of large measurement noises? 6.
What is the drawback of a P-only controller? What is the drawback of the derivative action? 7.
What are the causes of offset? 8.
What is the impact of derivative action on response? 9.
What is the impact of noise on derivative action? Positive
False
the
controller
output
(CO)
at
the
designed
set
point
and
expected
disturbance
the
controller
output
at
the
end
of
last
control
period
and
the
beginning
of
a
new
control
period
in
manual
mode
.
i
.
e
,
without
feedback
or
feed
forward
control
PB
=
100/
KC
This
is
the
input
change
that
cause
100
%
change
in
the
output
loss
of
symmetry
in
control
action
Offset
is
the
drawback
for
4-only
controller
.
Derivative
action
amplifies
noisy
measurements
into
excessive
control
value
movement
and
is
no
good
for
noisy
processes
such
as
flow
the
cause
of
offset
in
a
control
system
include
imperfect
turning
of
controller
parameters
,
dead
time
in
system
response
,
and
disturbances
that
the
controller
cannot
fully
compensate
for
Du
=
Kc
(SP-PV)
>
Du
:
derived
from
offset
and
is
needed
to
reach
new
SP
or
counterbalance
new
disturbance
Anti-change
,
anti-slope
,
and
anti-oscillation
Noise
is
amplified
in
the
controller
output
.
So
derivative
action
is
usually
avoided
in
flow
and
other
noisy
control
loops
10.
Write down the expression of derivative on measurement. 11.
What is ITAE? IAE? ISE? 12.
In PID controller, which action accounts for past history, which for current trajectory, and which for current value? 13.
What is PID disturbance rejection? What is set point tracking? 14.
What is R-squared in a dynamic model fit? 15.
What is a bumpless transfer? 16.
When doing a plant test to fit the process model or the disturbance model, what condition is preferred, open-loop or closed-loop? 17.
What is a reverse acting controller? 18.
What is the impact of too much filtering? -
Ec
.
Ta
.
dt
ITAE
:
Integral
time
weighted
absolute
error/integral
of
time
multiplied
by
absolute
error
IAE
:
Integral
of
absolute
error
ISE
:
Integral
of
square
of
error
Integral
:
past
history
derivative
:
current
trajectory
proportional
:
Current
value
changes
ability
to
maintain
the
process
variable
close
to
Disturbance
rejection
:
veter
to
a
control
system's
I
in
the
setpoint
despite
external
disturbance
operating
condition
setpoint
tracking
:
ability
of
a
control
system
to
adjust
the
process
variable
to
match
desired
match
point
R
:
the
goodness
fit
or
the
explained
variation
<
z(y
+
5)
=
(y
+
y)
+
z(yi
y
*
R2
=
SS
due
to
regression
=
z(yi
-
j)
:
SS
about
the
SS
due
to
SS
about
Total
SS
corrected
for
the
mean
(
2
(yi
-
y
2
mean
regression
regression
refer
to
a
seamless
transition
from
manual
control
mode
to
automatic
control
mode
,
eversa
in
control
system
.
(it
is
smoothly
transitioned
to
ensure
stability
in
control
system)
Ubias
(bias
controller
output)
:
set
to
current
value
of
manipulated
variable
(MV)
setpoint
(SP)
:
Set
to
current
value
of
the
process
variable
(CV)
,
ensuring
smooth
transition
without
sudden
changes
open-loop
.
However
,
almost
all
plant
data
are
closed
loop
.
Open-loop
data
are
from
special
tests
output
:
manipulated
variable
(MU)
,
controller
output
(k)
,
reverse
acting
controller
is
characterized
by
:
denoted
as
"4"
Ec
>
0
and
kp
>
O
Input
:
Process
Variable
(PV)
/controlled
variable
(CV)
,
denoted
as
"y"
increased
sluggish
in
controlled
variable
(CV)
responses
lead
to
larger
overshoot
.
This
effect
resembles
the
behavior
of
P1-controller
when
a
=
1
if
a
>1
,
the
responses
become
even
more
sluggish
than
a
P1
controller
19.
Why does the performance of a PID controller without a derivative filter degrade when the noise causes the controller output to hit an upper or lower limit? 20.
Why does Tank 2 remain in manual mode in workshop 7? 21.
What are the two things that hinder regulatory control? 22.
What is the effect of reset windup on response? 23.
What can you say about the balance between the robustness and performance of a controller? 24.
If you do the closed-loop plant testing, what change do you have to make to see the dynamics? 25.
In general, which tuning parameter set is more conservative, SP tracking or disturbance rejection? 26.
What is a direct acting controller? Without
a
derivative
filter
,
uneven
(un-symmetric)
manipulated
actions
can
result
when
the
controller
output
hit
an
upper
or
lower
limit
.
Because
the
"equality
or
symmetry
in
randomless"
is
lost
to
avoid
interaction
,
we
only
tune
Tank
1
(upper
&
lower)
Deadtime
and
noise
right
control
is
increasingly
difficult
when
Qp
>
0
7
Ip
it
causes
delayed
return
to
the
new
SP
because
it
has
to
generate
enough
error
to
"unwind"
the
saturated
manipulated
variable
.
leg)
if
during
saturation
,
it
continues
to
integrate
to
generate
excessive
"I
error
that
has
to
be
balanced
with
an
equal
amount
of
"-"
error
by
not
approaching
the
new
Sp
Take
jet
fighter
control
scheme
as
an
example
.
In
the
attack
mode
,
we
stress
the
performance
,
which
has
fast
responses
and
short
closed
loop
Ip
.
It
may
,
however
,
cause
overshoot
and
instability
.
In
the
landing
mode
,
the
stability
(safety)
requirements
demand
robustness
.
No
overshoot
is
tolerated
or
needed
setpoint
changes
or
measured
disturbance
changes
.
We
can
take
the
controller
output
data
and
the
response
data
to
figure
out
open-loop
dynamics
Disturbance
rejection
is
more
conservative
Direct
acting
means
that
when
the
input
(measurement)
is
up
,
the
output
(controller
out
to see
signal)
is
also
up
.
Usually
it
indicate
a
negative
Kc
.
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help
27.
What is the benefit and drawback of no overshoot? 28.
In PID control, how do you detect the nonlinear behavior in a closed-loop setting? 29.
In the jacketed reactor temperature feedforward control workshop (control station), which disturbance variable would you change, and which process variable would you observe to obtain the disturbance model? 30.
In the jacketed reactor temperature cascade control workshop (control station), which manipulated variable would you change, and which process variable would you observe to get the open-loop, first order plus dead time model for the primary loop? 31.
What are the units of the input (DV) and the output (CV) in the disturbance model in the feed forward plus feedback control of jacketed CSTR (Workshop II)? What is the unit of KD? 32.
In the same Workshop 11, what is the unit of the input (MV) and what is the unit of output (CV) in the process model? What is the unit of'Kp? (6%) What is the unit of Kc and why? (4%) Drawback
:
sluggish
response
Benefit
:
minimal
variance
and
less
chance
of
upsetting
the
unit
1
.
Change
setpoint
2
.
Observe
difference
in
overshoot/oscillation/settling
time
I
Disturbance
variable
:
temperature
inlet
to
cooling
jacket
Process
variable
:
reactor
outlet
temperature
To
Manipulate
variable
:
setpoint
of
secondary
controller
(jacket
temp
control
Process
variable
:
reactor
outlet
temperature
[DV)
=
02
Ep
=
%
%
C
or
dimensionles
[CV]
=
°
C
[MV]
=
%
[Kc
=
Tip
=
[CV]
=
°C
[Rp7
:
%4
%
33.
What is the meaning of P=RA used to characterize a PIDF controller in Control Station case studies plots? Is Kc, positive or negative in this case (4%) 34.
What are the meanings ofF=off, D= ideal (meas), and I=ARW? (6%) 35.
What is the bias for a 4-mode PIDF controller (4%) 36.
What are the reasons to adopt a combined feedforward/feedback controller? 37.
What are the units of Kp and Kc of the inner loop in WS10 cascade control of a jacketed reactor 38.
where the manipulated variable is the cooling water flow rate (in %) and the controlled variable is 39.
the reactor outlet temperature (in °C)? 40.
What is the difference between “fluctuations” and “oscillations”? Dynamics: 1.
What are the major causes of dead time? Reverse
action
or
Ke
>
O
RA
:
reverse
action
Kc
>
O
No
filter
,
-KTpA
,
Anti
Rest
Windu
the
CO
is
in
the
beginning
of
a
control
cycle
Bias
is
the
controller
output
at
the
last
control
period
/the
beginning
of
a
new
control
period
to
take
care
of
unmeasured
disturbance
for
model
mismatch
·
for
metering
*
[Kp]
=
0C/
%
[Rc]
=
%
/
&
*
Fluctuation
:
control
value
Movement(s)
controller
output
Oscillation
:
peak
overshoot
ratio
higher-order
response
(like
,
heat
and
mass
transfer
delay)
,
transportation
lag
(like
fluid
How
delay)
,
and
simple
or
instrument
lag
(like
sensor
delay
such
as
GC
analysis
2.
When Kp_ is negative, what does it mean? 3.
What is pulse testing? Doublet Testing? 4.
What is a typical sampling time? 5.
What is a noise band? What is the normally adopted signal to noise ratio? 6.
If you do the closed loop plant testing, what change do you have to make to see the dynamics? 7.
What is overdamped? 8.
How can you tell a process is nonlinear from a y vs. u (steady state) plot? How can you tell a process is nonlinear from )y/)u? 9.
What are characteristics that define a process being linear? 10.
Write down the first order plus dead time model in terms of a differential equation (time domain expression). Du
:
the
controller
output
(CO)
moves
in
the
opposite
direction
Dy
:
The
process
variable
(PV)
moves
in
the
opposite
direction
of
the
setpoint
(SP)
Pulse
testing
:
a
step
change
followed
by
another
step
change
returning
to
the
baseline
.
Doublet
testing
:
a
step
change
followed
by
another
step
change
to
the
opposite
side
of
the
baseline
,
then
a
final
step
change
returning
to
the
baseline
.
is
is
approximately
0
1
times
the
process
time
constant
Ip
noise
band
:
+
32
or
+
30
!
signal
to
noise
ratio
:
10
:
I
setpoint
changes
or
measured
disturbance
changes
.
We
can
take
the
controller
output
data
and
the
response
data
to
figure
out
open-loop
dynamics
the
damping
coefficient
is
greater
than
1
in
a
second-order
system
you
can
tell
a
process
is
nonlinear
from
a
steady-state
y
vs
a
plot
if
the
curve
is
not
linear
.
similarly
a
process
is
nonlinear
from
the
slope
by
if
it's
not
constant
a
the
gain
(A)
is
constant
or
a
steady
state
y
vs
.
U
plot
is
a
straight
t
line
throughout
the
operating
range
,
kp
,
Ip
and
Op
are
constant
y(t)
:
process
variable
(PV)
at
time
+
Ip
:
process
time
constant
[p
(t)
+
y(t)
=
kp
m
u(t
D)
kp
:
process
gain
m
:
Input
multiplier
ult)
:
input
signal
D
:
dead
time
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help
11.
In PID control, how do you detect the nonlinear behavior in the presence of large measurement noises? 12.
What are the reasons to adopt a combined feedforward/feedback controller? 13.
What are the units of Kp and Kc of the inner loop in WS10 cascade control of a jacketed reactor 14.
where the manipulated variable is the cooling water flow rate (in %) and the controlled variable is the reactor outlet temperature (in °C)? 15.
What is the diference between “fluctuations” and “oscillations”? change
setpoint
(SP)
observe
differences
in
overshoot/oscillation/settling
time
to
take
care
of
unmeasured
disturbance
for
model
mismatch
·
for
metering
*
[Kp]
=
0C/
%
[Rc]
=
%
/
④
Fluctuation
:
randon
or
irregular
variations
in
signal
or
system
oscillation
:
repetitive
and
periodic
variations
around
central
value
16
.
What
is
the
sense
of
a
controller
?
sense
is
an
indication
of
positive
or
negative
(the
sign
of
Kel
17
.
What
is
the
difference
between
PV
&
CV
?
PV
:
Process
variable
,
which
is
resulting
and
recorded
(observed)
output
CV
:
Controlled
Variable
,
which
is
the
designed
output