Auto-Tuning Introduction - ABB COMMANDER 1911 Operating Manual

...5 CONTROL OPERATION

5.7 Auto-tuning Introduction

Information.
• On demand user-activated tuning.
• Two types of auto-tuning – initial
• Tuning for P, P.I. or P.I.D. control can be selected.
1
• Tuning for / wave damped or minimum overshoot can be selected.
4
• Automatic entry of calculated control terms – unless an auto-tune error occurs.
• Error and Caution messages – indicate reason for tuning problems.
Calculated Trip
Point
PV
Output
Information. The noise level of the
process is monitored and then a step is applied
to the control output value. The response of the
process is recorded and these results are used
to calculate the control terms.
Fig. 5.6 'Start-up' Auto-tuning
20
and when close to
'Start-up'
Set Point
Time
Output Step
Size
Time
.
Set Point
Self-tune High Limit
Signal Noise
Values at
Start of
Self-tune Low Limit
Execution
Controller
Output
Information. 'At Set Point' auto-tuning
automatically calculates the P.I.D. terms based
on the process reaction during an auto-tuning
cycle. The controller output is manipulated to give
six process oscillations which are used to
determine the tuning parameters.
Fig. 5.7 'At Set Point' Auto-tuning
Hysteresis Hysteresis
Value Band
Output Step
Time