UC800 AFD Operation
40
AFDE-SVU02F-EN
Re-optimization
The AF Surge Boundary Offset Coefficient is a user settable
parameter to be used for adjusting the surge boundary
either higher or lower. In addition to being user settable,
the surge control algorithm will periodically readjust this
boundary. This re-optimization will occur when any of
three different criteria are met.
1. After startup stabilization the control will re-optimize
unless the surge is detected in that time period.
2. Every 30 minutes, the control will compare the current
IGV position with the IGV position at the end of the last
re-optimization time and, if greater than the user
adjustable sensitivity, will re-optimize.
3. When the re-optimization timer expires.
The control is re-optimized by increasing the AF Surge
Boundary Offset Coefficient every minute until surge
occurs. When surge occurs, the control will go into surge
recovery until the surge flag is removed and all of the re-
optimization timers will reset.
Figure 16.
Startup surge boundary
0.0
0.6
0.7
0.8
0.9
1.0
1.1
1.2
10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0
Pressure Coefficient Trajectory
Start to Full Load
Running surge boundary
Pressure Coefficient
Surge boundary for start up
Boundary increases by 0.1
after 30 minutes
IGV % Capacity
Full load
