DECS-200 Setup 6-17
In Figure 6-24, less overshoot is desired, KD (derivative gain) is increased.
Figure 6-21. Insufficient Derivative Gain
Figure 6-25 illustrates the final solution. Increased KD (derivative gain) decreases voltage overshoot.
Figure 6-22. Final Solution Step Response
Place the Start/Stop Switch in the Stop position........................................................................... ________
Place the system in AVR mode .................................................................................................... ________
Monitor the generator voltage soft start time ................................................................................ ________
Place the Start/Stop Switch in the Start position .......................................................................... ________
Use the Raise/Lower control to increase the terminal voltage to the setpoint.............................. ________
EXCITATION PERFORMANCE EVALUATION
In this performance evaluation, temporarily settings will be used to enable the testing of excitation
performance without stressing the machine or exceeding ancillary protection device settings. Procedures
are provided that will allow you to set your final operating values. This evaluation is a continuation of the
previous tests.
Off-Line Excitation Limiter Operation
In this test, with the generator set below the rated voltage output, the AVR setpoint will be set above the
maximum setting and the system should annunciate an alarm. If an alarm is not annuciated, the OEL gain
(KI and Kg) may be set too low. If an alarm is annunciated and the system oscillates, the OEL gain, (KI
and Kg) may be set too high.
Enable the Off-Line Overexcitation Limiter (OEL) ........................................................................ ________
Determine the field current required to reach 105% of the rated generator voltage. ................... ________
Set the off-line OEL for a value equal to the no load field current ................................................ ________
Lower the terminal voltage to 10% below rated............................................................................ ________
To speed performance in the following test, you may increase the OEL gain (KI and Kg terms).
On the AVR/FCR tab of the BESTCOMS Setting Adjustments screen, adjust the AVR setpoint
to 110% of the rated output. (the AVR Max setting should remain at 105%.) .............................. ________
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