Chapter 13 Performance of Feedback Control Systems

1
Chapter 13 Performance of Feedback Control
Systems
Measures of control performance
2
Control performance via closed-loop frequency
response S1.
3
S2.
Ex.
4
S1. Frequency responses
5
Note PI control is effective in rejecting slow
disturbances and very high frequency as well.
6
Ex. 13.1 PI controller with four cases of FOPDT
models
7
S1. Under Ciancone correlation for tuning
constants S2. Frequency responses
8
_at_ the best control performance depends on the
smallest AR
9
Ex. 13.2 A closed-loop system with two
disturbances with different frequencies
Sine disturbances
10
S1. Time responses for two sine disturbances
11
S2. Responses responses for both sine disturbances
Note The control performance for input No. 1 is
good due to the small AR.
12
Ex. 13.5 The feedback control can be successful
in attenuating a low frequency disturbance but
the high-frequency disturbance is difficult to
reduce with feedback control
13
Inverse response The process with inverse
responses is difficult to control, because the
initial response of the controlled variable is in
the wrong direction. Ex. 13.8 a series chemical
reactor with step in solvent flow (Fs). The
initial inverse response is due to the faster
effect of the residence time on the output than
the slow feed concentration effect. The model is
written as
14
(No Transcript)
15
_at_ The closed-loop response under PI control
16
? Ex. 13.11 To select appropriate modes for PID
or PI controller applied to the following process
17
_at_ Assessment of control designs
18
(No Transcript)
19
? Ex. 13.12 To select manipulated variable by the
following process
20
S1.
21
S2. CSTR model
22
S3. Five criteria are evaluated for tow
manipulated variables
23
S4. Dynamic responses under PI control _at_ Better
performance by manipulating valve ?A
24

• Exercises
• Q13.9 (Rank for four cases of output/input
  responses
• Q13.11 (?c0.77)