Siemens PCS 7 mit, ohne, with compensation, whithout compensation, i.e. with integral behaviour, mit, ohne, with compensation, whithout compensation, i.e. with integral behaviour

Introduction
8 MPC Level
V 1.0, Beitrags-ID: 42200753
Copyright  Siemens AG 2010 All rights reserved
Figure 2-1 Step response of a control loop with compensation (blue) and without
compensation (red), i.e. with integral behaviour.
010 20 30 40 50 60 70 80 90 100
0
0.5
1
1.5
2
2.5
3
StepRes ponse
Time (sec)
Amplitude
mit
Ausgleich
ohne
Ausgleich
010 20 30 40 50 60 70 80 90 100
0
0.5
1
1.5
2
2.5
3
StepRes ponse
Time (sec)
Amplitude
010 20 30 40 50 60 70 80 90 100
0
0.5
1
1.5
2
2.5
3
StepRes ponse
Time (sec)
Amplitude
with
compensation
whithout
compensation,
i.e. with
integral
behaviour
010 20 30 40 50 60 70 80 90 100
0
0.5
1
1.5
2
2.5
3
StepRes ponse
Time (sec)
Amplitude
010 20 30 40 50 60 70 80 90 100
0
0.5
1
1.5
2
2.5
3
StepRes ponse
Time (sec)
Amplitude
mit
Ausgleich
ohne
Ausgleich
010 20 30 40 50 60 70 80 90 100
0
0.5
1
1.5
2
2.5
3
StepRes ponse
Time (sec)
Amplitude
010 20 30 40 50 60 70 80 90 100
0
0.5
1
1.5
2
2.5
3
StepRes ponse
Time (sec)
Amplitude
with
compensation
whithout
compensation,
i.e. with
integral
behaviour
Unstable control loops cannot be stabilized without a controller. Therefore, switch-
ing a controller in such a loop to manual mode is not allowed for a longer time.
Hence, the recording of measurement data for the process identification (e.g. for
the PID tuner or the MPC configurator) via step experiments in open control loop is
not possible. The model type and the control algorithm of the MPC function block
are also inappropriate for unstable control loops. Therefore, the unstable part trans-
fer functions have to be stabilized by subordinated slave controllers before the ap-
plication of the MPC.